Merge remote-tracking branch 'regulator/topic/palmas' into v3.9-rc8

[mirror_ubuntu-hirsute-kernel.git] / drivers / gpu / drm / drm_fb_helper.c

/*
 * Copyright (c) 2006-2009 Red Hat Inc.
 * Copyright (c) 2006-2008 Intel Corporation
 * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
 *
 * DRM framebuffer helper functions
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting documentation, and
 * that the name of the copyright holders not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  The copyright holders make no representations
 * about the suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 *
 * Authors:
 *      Dave Airlie <airlied@linux.ie>
 *      Jesse Barnes <jesse.barnes@intel.com>
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/sysrq.h>
#include <linux/slab.h>
#include <linux/fb.h>
#include <linux/module.h>
#include <drm/drmP.h>
#include <drm/drm_crtc.h>
#include <drm/drm_fb_helper.h>
#include <drm/drm_crtc_helper.h>

MODULE_AUTHOR("David Airlie, Jesse Barnes");
MODULE_DESCRIPTION("DRM KMS helper");
MODULE_LICENSE("GPL and additional rights");

static LIST_HEAD(kernel_fb_helper_list);

/**
 * DOC: fbdev helpers
 *
 * The fb helper functions are useful to provide an fbdev on top of a drm kernel
 * mode setting driver. They can be used mostly independantely from the crtc
 * helper functions used by many drivers to implement the kernel mode setting
 * interfaces.
 *
 * Initialization is done as a three-step process with drm_fb_helper_init(),
 * drm_fb_helper_single_add_all_connectors() and drm_fb_helper_initial_config().
 * Drivers with fancier requirements than the default beheviour can override the
 * second step with their own code.  Teardown is done with drm_fb_helper_fini().
 *
 * At runtime drivers should restore the fbdev console by calling
 * drm_fb_helper_restore_fbdev_mode() from their ->lastclose callback. They
 * should also notify the fb helper code from updates to the output
 * configuration by calling drm_fb_helper_hotplug_event(). For easier
 * integration with the output polling code in drm_crtc_helper.c the modeset
 * code proves a ->output_poll_changed callback.
 *
 * All other functions exported by the fb helper library can be used to
 * implement the fbdev driver interface by the driver.
 */

/**
 * drm_fb_helper_single_add_all_connectors() - add all connectors to fbdev
 *                                             emulation helper
 * @fb_helper: fbdev initialized with drm_fb_helper_init
 *
 * This functions adds all the available connectors for use with the given
 * fb_helper. This is a separate step to allow drivers to freely assign
 * connectors to the fbdev, e.g. if some are reserved for special purposes or
 * not adequate to be used for the fbcon.
 *
 * Since this is part of the initial setup before the fbdev is published, no
 * locking is required.
 */
int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper)
{
        struct drm_device *dev = fb_helper->dev;
        struct drm_connector *connector;
        int i;

        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
                struct drm_fb_helper_connector *fb_helper_connector;

                fb_helper_connector = kzalloc(sizeof(struct drm_fb_helper_connector), GFP_KERNEL);
                if (!fb_helper_connector)
                        goto fail;

                fb_helper_connector->connector = connector;
                fb_helper->connector_info[fb_helper->connector_count++] = fb_helper_connector;
        }
        return 0;
fail:
        for (i = 0; i < fb_helper->connector_count; i++) {
                kfree(fb_helper->connector_info[i]);
                fb_helper->connector_info[i] = NULL;
        }
        fb_helper->connector_count = 0;
        return -ENOMEM;
}
EXPORT_SYMBOL(drm_fb_helper_single_add_all_connectors);

static int drm_fb_helper_parse_command_line(struct drm_fb_helper *fb_helper)
{
        struct drm_fb_helper_connector *fb_helper_conn;
        int i;

        for (i = 0; i < fb_helper->connector_count; i++) {
                struct drm_cmdline_mode *mode;
                struct drm_connector *connector;
                char *option = NULL;

                fb_helper_conn = fb_helper->connector_info[i];
                connector = fb_helper_conn->connector;
                mode = &fb_helper_conn->cmdline_mode;

                /* do something on return - turn off connector maybe */
                if (fb_get_options(drm_get_connector_name(connector), &option))
                        continue;

                if (drm_mode_parse_command_line_for_connector(option,
                                                              connector,
                                                              mode)) {
                        if (mode->force) {
                                const char *s;
                                switch (mode->force) {
                                case DRM_FORCE_OFF:
                                        s = "OFF";
                                        break;
                                case DRM_FORCE_ON_DIGITAL:
                                        s = "ON - dig";
                                        break;
                                default:
                                case DRM_FORCE_ON:
                                        s = "ON";
                                        break;
                                }

                                DRM_INFO("forcing %s connector %s\n",
                                         drm_get_connector_name(connector), s);
                                connector->force = mode->force;
                        }

                        DRM_DEBUG_KMS("cmdline mode for connector %s %dx%d@%dHz%s%s%s\n",
                                      drm_get_connector_name(connector),
                                      mode->xres, mode->yres,
                                      mode->refresh_specified ? mode->refresh : 60,
                                      mode->rb ? " reduced blanking" : "",
                                      mode->margins ? " with margins" : "",
                                      mode->interlace ?  " interlaced" : "");
                }

        }
        return 0;
}

static void drm_fb_helper_save_lut_atomic(struct drm_crtc *crtc, struct drm_fb_helper *helper)
{
        uint16_t *r_base, *g_base, *b_base;
        int i;

        r_base = crtc->gamma_store;
        g_base = r_base + crtc->gamma_size;
        b_base = g_base + crtc->gamma_size;

        for (i = 0; i < crtc->gamma_size; i++)
                helper->funcs->gamma_get(crtc, &r_base[i], &g_base[i], &b_base[i], i);
}

static void drm_fb_helper_restore_lut_atomic(struct drm_crtc *crtc)
{
        uint16_t *r_base, *g_base, *b_base;

        if (crtc->funcs->gamma_set == NULL)
                return;

        r_base = crtc->gamma_store;
        g_base = r_base + crtc->gamma_size;
        b_base = g_base + crtc->gamma_size;

        crtc->funcs->gamma_set(crtc, r_base, g_base, b_base, 0, crtc->gamma_size);
}

/**
 * drm_fb_helper_debug_enter - implementation for ->fb_debug_enter
 * @info: fbdev registered by the helper
 */
int drm_fb_helper_debug_enter(struct fb_info *info)
{
        struct drm_fb_helper *helper = info->par;
        struct drm_crtc_helper_funcs *funcs;
        int i;

        if (list_empty(&kernel_fb_helper_list))
                return false;

        list_for_each_entry(helper, &kernel_fb_helper_list, kernel_fb_list) {
                for (i = 0; i < helper->crtc_count; i++) {
                        struct drm_mode_set *mode_set =
                                &helper->crtc_info[i].mode_set;

                        if (!mode_set->crtc->enabled)
                                continue;

                        funcs = mode_set->crtc->helper_private;
                        drm_fb_helper_save_lut_atomic(mode_set->crtc, helper);
                        funcs->mode_set_base_atomic(mode_set->crtc,
                                                    mode_set->fb,
                                                    mode_set->x,
                                                    mode_set->y,
                                                    ENTER_ATOMIC_MODE_SET);
                }
        }

        return 0;
}
EXPORT_SYMBOL(drm_fb_helper_debug_enter);

/* Find the real fb for a given fb helper CRTC */
static struct drm_framebuffer *drm_mode_config_fb(struct drm_crtc *crtc)
{
        struct drm_device *dev = crtc->dev;
        struct drm_crtc *c;

        list_for_each_entry(c, &dev->mode_config.crtc_list, head) {
                if (crtc->base.id == c->base.id)
                        return c->fb;
        }

        return NULL;
}

/**
 * drm_fb_helper_debug_leave - implementation for ->fb_debug_leave
 * @info: fbdev registered by the helper
 */
int drm_fb_helper_debug_leave(struct fb_info *info)
{
        struct drm_fb_helper *helper = info->par;
        struct drm_crtc *crtc;
        struct drm_crtc_helper_funcs *funcs;
        struct drm_framebuffer *fb;
        int i;

        for (i = 0; i < helper->crtc_count; i++) {
                struct drm_mode_set *mode_set = &helper->crtc_info[i].mode_set;
                crtc = mode_set->crtc;
                funcs = crtc->helper_private;
                fb = drm_mode_config_fb(crtc);

                if (!crtc->enabled)
                        continue;

                if (!fb) {
                        DRM_ERROR("no fb to restore??\n");
                        continue;
                }

                drm_fb_helper_restore_lut_atomic(mode_set->crtc);
                funcs->mode_set_base_atomic(mode_set->crtc, fb, crtc->x,
                                            crtc->y, LEAVE_ATOMIC_MODE_SET);
        }

        return 0;
}
EXPORT_SYMBOL(drm_fb_helper_debug_leave);

/**
 * drm_fb_helper_restore_fbdev_mode - restore fbdev configuration
 * @fb_helper: fbcon to restore
 *
 * This should be called from driver's drm ->lastclose callback
 * when implementing an fbcon on top of kms using this helper. This ensures that
 * the user isn't greeted with a black screen when e.g. X dies.
 */
bool drm_fb_helper_restore_fbdev_mode(struct drm_fb_helper *fb_helper)
{
        bool error = false;
        int i, ret;

        drm_warn_on_modeset_not_all_locked(fb_helper->dev);

        for (i = 0; i < fb_helper->crtc_count; i++) {
                struct drm_mode_set *mode_set = &fb_helper->crtc_info[i].mode_set;
                ret = drm_mode_set_config_internal(mode_set);
                if (ret)
                        error = true;
        }
        return error;
}
EXPORT_SYMBOL(drm_fb_helper_restore_fbdev_mode);

/*
 * restore fbcon display for all kms driver's using this helper, used for sysrq
 * and panic handling.
 */
static bool drm_fb_helper_force_kernel_mode(void)
{
        bool ret, error = false;
        struct drm_fb_helper *helper;

        if (list_empty(&kernel_fb_helper_list))
                return false;

        list_for_each_entry(helper, &kernel_fb_helper_list, kernel_fb_list) {
                if (helper->dev->switch_power_state == DRM_SWITCH_POWER_OFF)
                        continue;

                ret = drm_fb_helper_restore_fbdev_mode(helper);
                if (ret)
                        error = true;
        }
        return error;
}

static int drm_fb_helper_panic(struct notifier_block *n, unsigned long ununsed,
                        void *panic_str)
{
        /*
         * It's a waste of time and effort to switch back to text console
         * if the kernel should reboot before panic messages can be seen.
         */
        if (panic_timeout < 0)
                return 0;

        pr_err("panic occurred, switching back to text console\n");
        return drm_fb_helper_force_kernel_mode();
}

static struct notifier_block paniced = {
        .notifier_call = drm_fb_helper_panic,
};

static bool drm_fb_helper_is_bound(struct drm_fb_helper *fb_helper)
{
        struct drm_device *dev = fb_helper->dev;
        struct drm_crtc *crtc;
        int bound = 0, crtcs_bound = 0;

        list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
                if (crtc->fb)
                        crtcs_bound++;
                if (crtc->fb == fb_helper->fb)
                        bound++;
        }

        if (bound < crtcs_bound)
                return false;
        return true;
}

#ifdef CONFIG_MAGIC_SYSRQ
static void drm_fb_helper_restore_work_fn(struct work_struct *ignored)
{
        bool ret;
        ret = drm_fb_helper_force_kernel_mode();
        if (ret == true)
                DRM_ERROR("Failed to restore crtc configuration\n");
}
static DECLARE_WORK(drm_fb_helper_restore_work, drm_fb_helper_restore_work_fn);

static void drm_fb_helper_sysrq(int dummy1)
{
        schedule_work(&drm_fb_helper_restore_work);
}

static struct sysrq_key_op sysrq_drm_fb_helper_restore_op = {
        .handler = drm_fb_helper_sysrq,
        .help_msg = "force-fb(V)",
        .action_msg = "Restore framebuffer console",
};
#else
static struct sysrq_key_op sysrq_drm_fb_helper_restore_op = { };
#endif

static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
{
        struct drm_fb_helper *fb_helper = info->par;
        struct drm_device *dev = fb_helper->dev;
        struct drm_crtc *crtc;
        struct drm_connector *connector;
        int i, j;

        /*
         * fbdev->blank can be called from irq context in case of a panic.
         * Since we already have our own special panic handler which will
         * restore the fbdev console mode completely, just bail out early.
         */
        if (oops_in_progress)
                return;

        /*
         * For each CRTC in this fb, turn the connectors on/off.
         */
        drm_modeset_lock_all(dev);
        if (!drm_fb_helper_is_bound(fb_helper)) {
                drm_modeset_unlock_all(dev);
                return;
        }

        for (i = 0; i < fb_helper->crtc_count; i++) {
                crtc = fb_helper->crtc_info[i].mode_set.crtc;

                if (!crtc->enabled)
                        continue;

                /* Walk the connectors & encoders on this fb turning them on/off */
                for (j = 0; j < fb_helper->connector_count; j++) {
                        connector = fb_helper->connector_info[j]->connector;
                        connector->funcs->dpms(connector, dpms_mode);
                        drm_object_property_set_value(&connector->base,
                                dev->mode_config.dpms_property, dpms_mode);
                }
        }
        drm_modeset_unlock_all(dev);
}

/**
 * drm_fb_helper_blank - implementation for ->fb_blank
 * @blank: desired blanking state
 * @info: fbdev registered by the helper
 */
int drm_fb_helper_blank(int blank, struct fb_info *info)
{
        switch (blank) {
        /* Display: On; HSync: On, VSync: On */
        case FB_BLANK_UNBLANK:
                drm_fb_helper_dpms(info, DRM_MODE_DPMS_ON);
                break;
        /* Display: Off; HSync: On, VSync: On */
        case FB_BLANK_NORMAL:
                drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY);
                break;
        /* Display: Off; HSync: Off, VSync: On */
        case FB_BLANK_HSYNC_SUSPEND:
                drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY);
                break;
        /* Display: Off; HSync: On, VSync: Off */
        case FB_BLANK_VSYNC_SUSPEND:
                drm_fb_helper_dpms(info, DRM_MODE_DPMS_SUSPEND);
                break;
        /* Display: Off; HSync: Off, VSync: Off */
        case FB_BLANK_POWERDOWN:
                drm_fb_helper_dpms(info, DRM_MODE_DPMS_OFF);
                break;
        }
        return 0;
}
EXPORT_SYMBOL(drm_fb_helper_blank);

static void drm_fb_helper_crtc_free(struct drm_fb_helper *helper)
{
        int i;

        for (i = 0; i < helper->connector_count; i++)
                kfree(helper->connector_info[i]);
        kfree(helper->connector_info);
        for (i = 0; i < helper->crtc_count; i++) {
                kfree(helper->crtc_info[i].mode_set.connectors);
                if (helper->crtc_info[i].mode_set.mode)
                        drm_mode_destroy(helper->dev, helper->crtc_info[i].mode_set.mode);
        }
        kfree(helper->crtc_info);
}

/**
 * drm_fb_helper_init - initialize a drm_fb_helper structure
 * @dev: drm device
 * @fb_helper: driver-allocated fbdev helper structure to initialize
 * @crtc_count: maximum number of crtcs to support in this fbdev emulation
 * @max_conn_count: max connector count
 *
 * This allocates the structures for the fbdev helper with the given limits.
 * Note that this won't yet touch the hardware (through the driver interfaces)
 * nor register the fbdev. This is only done in drm_fb_helper_initial_config()
 * to allow driver writes more control over the exact init sequence.
 *
 * Drivers must set fb_helper->funcs before calling
 * drm_fb_helper_initial_config().
 *
 * RETURNS:
 * Zero if everything went ok, nonzero otherwise.
 */
int drm_fb_helper_init(struct drm_device *dev,
                       struct drm_fb_helper *fb_helper,
                       int crtc_count, int max_conn_count)
{
        struct drm_crtc *crtc;
        int i;

        fb_helper->dev = dev;

        INIT_LIST_HEAD(&fb_helper->kernel_fb_list);

        fb_helper->crtc_info = kcalloc(crtc_count, sizeof(struct drm_fb_helper_crtc), GFP_KERNEL);
        if (!fb_helper->crtc_info)
                return -ENOMEM;

        fb_helper->crtc_count = crtc_count;
        fb_helper->connector_info = kcalloc(dev->mode_config.num_connector, sizeof(struct drm_fb_helper_connector *), GFP_KERNEL);
        if (!fb_helper->connector_info) {
                kfree(fb_helper->crtc_info);
                return -ENOMEM;
        }
        fb_helper->connector_count = 0;

        for (i = 0; i < crtc_count; i++) {
                fb_helper->crtc_info[i].mode_set.connectors =
                        kcalloc(max_conn_count,
                                sizeof(struct drm_connector *),
                                GFP_KERNEL);

                if (!fb_helper->crtc_info[i].mode_set.connectors)
                        goto out_free;
                fb_helper->crtc_info[i].mode_set.num_connectors = 0;
        }

        i = 0;
        list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
                fb_helper->crtc_info[i].mode_set.crtc = crtc;
                i++;
        }

        return 0;
out_free:
        drm_fb_helper_crtc_free(fb_helper);
        return -ENOMEM;
}
EXPORT_SYMBOL(drm_fb_helper_init);

void drm_fb_helper_fini(struct drm_fb_helper *fb_helper)
{
        if (!list_empty(&fb_helper->kernel_fb_list)) {
                list_del(&fb_helper->kernel_fb_list);
                if (list_empty(&kernel_fb_helper_list)) {
                        pr_info("drm: unregistered panic notifier\n");
                        atomic_notifier_chain_unregister(&panic_notifier_list,
                                                         &paniced);
                        unregister_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
                }
        }

        drm_fb_helper_crtc_free(fb_helper);

}
EXPORT_SYMBOL(drm_fb_helper_fini);

static int setcolreg(struct drm_crtc *crtc, u16 red, u16 green,
                     u16 blue, u16 regno, struct fb_info *info)
{
        struct drm_fb_helper *fb_helper = info->par;
        struct drm_framebuffer *fb = fb_helper->fb;
        int pindex;

        if (info->fix.visual == FB_VISUAL_TRUECOLOR) {
                u32 *palette;
                u32 value;
                /* place color in psuedopalette */
                if (regno > 16)
                        return -EINVAL;
                palette = (u32 *)info->pseudo_palette;
                red >>= (16 - info->var.red.length);
                green >>= (16 - info->var.green.length);
                blue >>= (16 - info->var.blue.length);
                value = (red << info->var.red.offset) |
                        (green << info->var.green.offset) |
                        (blue << info->var.blue.offset);
                if (info->var.transp.length > 0) {
                        u32 mask = (1 << info->var.transp.length) - 1;
                        mask <<= info->var.transp.offset;
                        value |= mask;
                }
                palette[regno] = value;
                return 0;
        }

        pindex = regno;

        if (fb->bits_per_pixel == 16) {
                pindex = regno << 3;

                if (fb->depth == 16 && regno > 63)
                        return -EINVAL;
                if (fb->depth == 15 && regno > 31)
                        return -EINVAL;

                if (fb->depth == 16) {
                        u16 r, g, b;
                        int i;
                        if (regno < 32) {
                                for (i = 0; i < 8; i++)
                                        fb_helper->funcs->gamma_set(crtc, red,
                                                green, blue, pindex + i);
                        }

                        fb_helper->funcs->gamma_get(crtc, &r,
                                                    &g, &b,
                                                    pindex >> 1);

                        for (i = 0; i < 4; i++)
                                fb_helper->funcs->gamma_set(crtc, r,
                                                            green, b,
                                                            (pindex >> 1) + i);
                }
        }

        if (fb->depth != 16)
                fb_helper->funcs->gamma_set(crtc, red, green, blue, pindex);
        return 0;
}

/**
 * drm_fb_helper_setcmap - implementation for ->fb_setcmap
 * @cmap: cmap to set
 * @info: fbdev registered by the helper
 */
int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
{
        struct drm_fb_helper *fb_helper = info->par;
        struct drm_crtc_helper_funcs *crtc_funcs;
        u16 *red, *green, *blue, *transp;
        struct drm_crtc *crtc;
        int i, j, rc = 0;
        int start;

        for (i = 0; i < fb_helper->crtc_count; i++) {
                crtc = fb_helper->crtc_info[i].mode_set.crtc;
                crtc_funcs = crtc->helper_private;

                red = cmap->red;
                green = cmap->green;
                blue = cmap->blue;
                transp = cmap->transp;
                start = cmap->start;

                for (j = 0; j < cmap->len; j++) {
                        u16 hred, hgreen, hblue, htransp = 0xffff;

                        hred = *red++;
                        hgreen = *green++;
                        hblue = *blue++;

                        if (transp)
                                htransp = *transp++;

                        rc = setcolreg(crtc, hred, hgreen, hblue, start++, info);
                        if (rc)
                                return rc;
                }
                crtc_funcs->load_lut(crtc);
        }
        return rc;
}
EXPORT_SYMBOL(drm_fb_helper_setcmap);

/**
 * drm_fb_helper_check_var - implementation for ->fb_check_var
 * @var: screeninfo to check
 * @info: fbdev registered by the helper
 */
int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
                            struct fb_info *info)
{
        struct drm_fb_helper *fb_helper = info->par;
        struct drm_framebuffer *fb = fb_helper->fb;
        int depth;

        if (var->pixclock != 0 || in_dbg_master())
                return -EINVAL;

        /* Need to resize the fb object !!! */
        if (var->bits_per_pixel > fb->bits_per_pixel ||
            var->xres > fb->width || var->yres > fb->height ||
            var->xres_virtual > fb->width || var->yres_virtual > fb->height) {
                DRM_DEBUG("fb userspace requested width/height/bpp is greater than current fb "
                          "request %dx%d-%d (virtual %dx%d) > %dx%d-%d\n",
                          var->xres, var->yres, var->bits_per_pixel,
                          var->xres_virtual, var->yres_virtual,
                          fb->width, fb->height, fb->bits_per_pixel);
                return -EINVAL;
        }

        switch (var->bits_per_pixel) {
        case 16:
                depth = (var->green.length == 6) ? 16 : 15;
                break;
        case 32:
                depth = (var->transp.length > 0) ? 32 : 24;
                break;
        default:
                depth = var->bits_per_pixel;
                break;
        }

        switch (depth) {
        case 8:
                var->red.offset = 0;
                var->green.offset = 0;
                var->blue.offset = 0;
                var->red.length = 8;
                var->green.length = 8;
                var->blue.length = 8;
                var->transp.length = 0;
                var->transp.offset = 0;
                break;
        case 15:
                var->red.offset = 10;
                var->green.offset = 5;
                var->blue.offset = 0;
                var->red.length = 5;
                var->green.length = 5;
                var->blue.length = 5;
                var->transp.length = 1;
                var->transp.offset = 15;
                break;
        case 16:
                var->red.offset = 11;
                var->green.offset = 5;
                var->blue.offset = 0;
                var->red.length = 5;
                var->green.length = 6;
                var->blue.length = 5;
                var->transp.length = 0;
                var->transp.offset = 0;
                break;
        case 24:
                var->red.offset = 16;
                var->green.offset = 8;
                var->blue.offset = 0;
                var->red.length = 8;
                var->green.length = 8;
                var->blue.length = 8;
                var->transp.length = 0;
                var->transp.offset = 0;
                break;
        case 32:
                var->red.offset = 16;
                var->green.offset = 8;
                var->blue.offset = 0;
                var->red.length = 8;
                var->green.length = 8;
                var->blue.length = 8;
                var->transp.length = 8;
                var->transp.offset = 24;
                break;
        default:
                return -EINVAL;
        }
        return 0;
}
EXPORT_SYMBOL(drm_fb_helper_check_var);

/**
 * drm_fb_helper_set_par - implementation for ->fb_set_par
 * @info: fbdev registered by the helper
 *
 * This will let fbcon do the mode init and is called at initialization time by
 * the fbdev core when registering the driver, and later on through the hotplug
 * callback.
 */
int drm_fb_helper_set_par(struct fb_info *info)
{
        struct drm_fb_helper *fb_helper = info->par;
        struct drm_device *dev = fb_helper->dev;
        struct fb_var_screeninfo *var = &info->var;
        int ret;
        int i;

        if (var->pixclock != 0) {
                DRM_ERROR("PIXEL CLOCK SET\n");
                return -EINVAL;
        }

        drm_modeset_lock_all(dev);
        for (i = 0; i < fb_helper->crtc_count; i++) {
                ret = drm_mode_set_config_internal(&fb_helper->crtc_info[i].mode_set);
                if (ret) {
                        drm_modeset_unlock_all(dev);
                        return ret;
                }
        }
        drm_modeset_unlock_all(dev);

        if (fb_helper->delayed_hotplug) {
                fb_helper->delayed_hotplug = false;
                drm_fb_helper_hotplug_event(fb_helper);
        }
        return 0;
}
EXPORT_SYMBOL(drm_fb_helper_set_par);

/**
 * drm_fb_helper_pan_display - implementation for ->fb_pan_display
 * @var: updated screen information
 * @info: fbdev registered by the helper
 */
int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
                              struct fb_info *info)
{
        struct drm_fb_helper *fb_helper = info->par;
        struct drm_device *dev = fb_helper->dev;
        struct drm_mode_set *modeset;
        struct drm_crtc *crtc;
        int ret = 0;
        int i;

        drm_modeset_lock_all(dev);
        if (!drm_fb_helper_is_bound(fb_helper)) {
                drm_modeset_unlock_all(dev);
                return -EBUSY;
        }

        for (i = 0; i < fb_helper->crtc_count; i++) {
                crtc = fb_helper->crtc_info[i].mode_set.crtc;

                modeset = &fb_helper->crtc_info[i].mode_set;

                modeset->x = var->xoffset;
                modeset->y = var->yoffset;

                if (modeset->num_connectors) {
                        ret = drm_mode_set_config_internal(modeset);
                        if (!ret) {
                                info->var.xoffset = var->xoffset;
                                info->var.yoffset = var->yoffset;
                        }
                }
        }
        drm_modeset_unlock_all(dev);
        return ret;
}
EXPORT_SYMBOL(drm_fb_helper_pan_display);

/*
 * Allocates the backing storage and sets up the fbdev info structure through
 * the ->fb_probe callback and then registers the fbdev and sets up the panic
 * notifier.
 */
static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
                                         int preferred_bpp)
{
        int ret = 0;
        int crtc_count = 0;
        int i;
        struct fb_info *info;
        struct drm_fb_helper_surface_size sizes;
        int gamma_size = 0;

        memset(&sizes, 0, sizeof(struct drm_fb_helper_surface_size));
        sizes.surface_depth = 24;
        sizes.surface_bpp = 32;
        sizes.fb_width = (unsigned)-1;
        sizes.fb_height = (unsigned)-1;

        /* if driver picks 8 or 16 by default use that
           for both depth/bpp */
        if (preferred_bpp != sizes.surface_bpp)
                sizes.surface_depth = sizes.surface_bpp = preferred_bpp;

        /* first up get a count of crtcs now in use and new min/maxes width/heights */
        for (i = 0; i < fb_helper->connector_count; i++) {
                struct drm_fb_helper_connector *fb_helper_conn = fb_helper->connector_info[i];
                struct drm_cmdline_mode *cmdline_mode;

                cmdline_mode = &fb_helper_conn->cmdline_mode;

                if (cmdline_mode->bpp_specified) {
                        switch (cmdline_mode->bpp) {
                        case 8:
                                sizes.surface_depth = sizes.surface_bpp = 8;
                                break;
                        case 15:
                                sizes.surface_depth = 15;
                                sizes.surface_bpp = 16;
                                break;
                        case 16:
                                sizes.surface_depth = sizes.surface_bpp = 16;
                                break;
                        case 24:
                                sizes.surface_depth = sizes.surface_bpp = 24;
                                break;
                        case 32:
                                sizes.surface_depth = 24;
                                sizes.surface_bpp = 32;
                                break;
                        }
                        break;
                }
        }

        crtc_count = 0;
        for (i = 0; i < fb_helper->crtc_count; i++) {
                struct drm_display_mode *desired_mode;
                desired_mode = fb_helper->crtc_info[i].desired_mode;

                if (desired_mode) {
                        if (gamma_size == 0)
                                gamma_size = fb_helper->crtc_info[i].mode_set.crtc->gamma_size;
                        if (desired_mode->hdisplay < sizes.fb_width)
                                sizes.fb_width = desired_mode->hdisplay;
                        if (desired_mode->vdisplay < sizes.fb_height)
                                sizes.fb_height = desired_mode->vdisplay;
                        if (desired_mode->hdisplay > sizes.surface_width)
                                sizes.surface_width = desired_mode->hdisplay;
                        if (desired_mode->vdisplay > sizes.surface_height)
                                sizes.surface_height = desired_mode->vdisplay;
                        crtc_count++;
                }
        }

        if (crtc_count == 0 || sizes.fb_width == -1 || sizes.fb_height == -1) {
                /* hmm everyone went away - assume VGA cable just fell out
                   and will come back later. */
                DRM_INFO("Cannot find any crtc or sizes - going 1024x768\n");
                sizes.fb_width = sizes.surface_width = 1024;
                sizes.fb_height = sizes.surface_height = 768;
        }

        /* push down into drivers */
        ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes);
        if (ret < 0)
                return ret;

        info = fb_helper->fbdev;

        /*
         * Set the fb pointer - usually drm_setup_crtcs does this for hotplug
         * events, but at init time drm_setup_crtcs needs to be called before
         * the fb is allocated (since we need to figure out the desired size of
         * the fb before we can allocate it ...). Hence we need to fix things up
         * here again.
         */
        for (i = 0; i < fb_helper->crtc_count; i++)
                if (fb_helper->crtc_info[i].mode_set.num_connectors)
                        fb_helper->crtc_info[i].mode_set.fb = fb_helper->fb;


        info->var.pixclock = 0;
        if (register_framebuffer(info) < 0)
                return -EINVAL;

        dev_info(fb_helper->dev->dev, "fb%d: %s frame buffer device\n",
                        info->node, info->fix.id);

        /* Switch back to kernel console on panic */
        /* multi card linked list maybe */
        if (list_empty(&kernel_fb_helper_list)) {
                dev_info(fb_helper->dev->dev, "registered panic notifier\n");
                atomic_notifier_chain_register(&panic_notifier_list,
                                               &paniced);
                register_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
        }

        list_add(&fb_helper->kernel_fb_list, &kernel_fb_helper_list);

        return 0;
}

/**
 * drm_fb_helper_fill_fix - initializes fixed fbdev information
 * @info: fbdev registered by the helper
 * @pitch: desired pitch
 * @depth: desired depth
 *
 * Helper to fill in the fixed fbdev information useful for a non-accelerated
 * fbdev emulations. Drivers which support acceleration methods which impose
 * additional constraints need to set up their own limits.
 *
 * Drivers should call this (or their equivalent setup code) from their
 * ->fb_probe callback.
 */
void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
                            uint32_t depth)
{
        info->fix.type = FB_TYPE_PACKED_PIXELS;
        info->fix.visual = depth == 8 ? FB_VISUAL_PSEUDOCOLOR :
                FB_VISUAL_TRUECOLOR;
        info->fix.mmio_start = 0;
        info->fix.mmio_len = 0;
        info->fix.type_aux = 0;
        info->fix.xpanstep = 1; /* doing it in hw */
        info->fix.ypanstep = 1; /* doing it in hw */
        info->fix.ywrapstep = 0;
        info->fix.accel = FB_ACCEL_NONE;
        info->fix.type_aux = 0;

        info->fix.line_length = pitch;
        return;
}
EXPORT_SYMBOL(drm_fb_helper_fill_fix);

/**
 * drm_fb_helper_fill_var - initalizes variable fbdev information
 * @info: fbdev instance to set up
 * @fb_helper: fb helper instance to use as template
 * @fb_width: desired fb width
 * @fb_height: desired fb height
 *
 * Sets up the variable fbdev metainformation from the given fb helper instance
 * and the drm framebuffer allocated in fb_helper->fb.
 *
 * Drivers should call this (or their equivalent setup code) from their
 * ->fb_probe callback after having allocated the fbdev backing
 * storage framebuffer.
 */
void drm_fb_helper_fill_var(struct fb_info *info, struct drm_fb_helper *fb_helper,
                            uint32_t fb_width, uint32_t fb_height)
{
        struct drm_framebuffer *fb = fb_helper->fb;
        info->pseudo_palette = fb_helper->pseudo_palette;
        info->var.xres_virtual = fb->width;
        info->var.yres_virtual = fb->height;
        info->var.bits_per_pixel = fb->bits_per_pixel;
        info->var.accel_flags = FB_ACCELF_TEXT;
        info->var.xoffset = 0;
        info->var.yoffset = 0;
        info->var.activate = FB_ACTIVATE_NOW;
        info->var.height = -1;
        info->var.width = -1;

        switch (fb->depth) {
        case 8:
                info->var.red.offset = 0;
                info->var.green.offset = 0;
                info->var.blue.offset = 0;
                info->var.red.length = 8; /* 8bit DAC */
                info->var.green.length = 8;
                info->var.blue.length = 8;
                info->var.transp.offset = 0;
                info->var.transp.length = 0;
                break;
        case 15:
                info->var.red.offset = 10;
                info->var.green.offset = 5;
                info->var.blue.offset = 0;
                info->var.red.length = 5;
                info->var.green.length = 5;
                info->var.blue.length = 5;
                info->var.transp.offset = 15;
                info->var.transp.length = 1;
                break;
        case 16:
                info->var.red.offset = 11;
                info->var.green.offset = 5;
                info->var.blue.offset = 0;
                info->var.red.length = 5;
                info->var.green.length = 6;
                info->var.blue.length = 5;
                info->var.transp.offset = 0;
                break;
        case 24:
                info->var.red.offset = 16;
                info->var.green.offset = 8;
                info->var.blue.offset = 0;
                info->var.red.length = 8;
                info->var.green.length = 8;
                info->var.blue.length = 8;
                info->var.transp.offset = 0;
                info->var.transp.length = 0;
                break;
        case 32:
                info->var.red.offset = 16;
                info->var.green.offset = 8;
                info->var.blue.offset = 0;
                info->var.red.length = 8;
                info->var.green.length = 8;
                info->var.blue.length = 8;
                info->var.transp.offset = 24;
                info->var.transp.length = 8;
                break;
        default:
                break;
        }

        info->var.xres = fb_width;
        info->var.yres = fb_height;
}
EXPORT_SYMBOL(drm_fb_helper_fill_var);

static int drm_fb_helper_probe_connector_modes(struct drm_fb_helper *fb_helper,
                                               uint32_t maxX,
                                               uint32_t maxY)
{
        struct drm_connector *connector;
        int count = 0;
        int i;

        for (i = 0; i < fb_helper->connector_count; i++) {
                connector = fb_helper->connector_info[i]->connector;
                count += connector->funcs->fill_modes(connector, maxX, maxY);
        }

        return count;
}

static struct drm_display_mode *drm_has_preferred_mode(struct drm_fb_helper_connector *fb_connector, int width, int height)
{
        struct drm_display_mode *mode;

        list_for_each_entry(mode, &fb_connector->connector->modes, head) {
                if (drm_mode_width(mode) > width ||
                    drm_mode_height(mode) > height)
                        continue;
                if (mode->type & DRM_MODE_TYPE_PREFERRED)
                        return mode;
        }
        return NULL;
}

static bool drm_has_cmdline_mode(struct drm_fb_helper_connector *fb_connector)
{
        struct drm_cmdline_mode *cmdline_mode;
        cmdline_mode = &fb_connector->cmdline_mode;
        return cmdline_mode->specified;
}

static struct drm_display_mode *drm_pick_cmdline_mode(struct drm_fb_helper_connector *fb_helper_conn,
                                                      int width, int height)
{
        struct drm_cmdline_mode *cmdline_mode;
        struct drm_display_mode *mode = NULL;

        cmdline_mode = &fb_helper_conn->cmdline_mode;
        if (cmdline_mode->specified == false)
                return mode;

        /* attempt to find a matching mode in the list of modes
         *  we have gotten so far, if not add a CVT mode that conforms
         */
        if (cmdline_mode->rb || cmdline_mode->margins)
                goto create_mode;

        list_for_each_entry(mode, &fb_helper_conn->connector->modes, head) {
                /* check width/height */
                if (mode->hdisplay != cmdline_mode->xres ||
                    mode->vdisplay != cmdline_mode->yres)
                        continue;

                if (cmdline_mode->refresh_specified) {
                        if (mode->vrefresh != cmdline_mode->refresh)
                                continue;
                }

                if (cmdline_mode->interlace) {
                        if (!(mode->flags & DRM_MODE_FLAG_INTERLACE))
                                continue;
                }
                return mode;
        }

create_mode:
        mode = drm_mode_create_from_cmdline_mode(fb_helper_conn->connector->dev,
                                                 cmdline_mode);
        list_add(&mode->head, &fb_helper_conn->connector->modes);
        return mode;
}

static bool drm_connector_enabled(struct drm_connector *connector, bool strict)
{
        bool enable;

        if (strict)
                enable = connector->status == connector_status_connected;
        else
                enable = connector->status != connector_status_disconnected;

        return enable;
}

static void drm_enable_connectors(struct drm_fb_helper *fb_helper,
                                  bool *enabled)
{
        bool any_enabled = false;
        struct drm_connector *connector;
        int i = 0;

        for (i = 0; i < fb_helper->connector_count; i++) {
                connector = fb_helper->connector_info[i]->connector;
                enabled[i] = drm_connector_enabled(connector, true);
                DRM_DEBUG_KMS("connector %d enabled? %s\n", connector->base.id,
                          enabled[i] ? "yes" : "no");
                any_enabled |= enabled[i];
        }

        if (any_enabled)
                return;

        for (i = 0; i < fb_helper->connector_count; i++) {
                connector = fb_helper->connector_info[i]->connector;
                enabled[i] = drm_connector_enabled(connector, false);
        }
}

static bool drm_target_cloned(struct drm_fb_helper *fb_helper,
                              struct drm_display_mode **modes,
                              bool *enabled, int width, int height)
{
        int count, i, j;
        bool can_clone = false;
        struct drm_fb_helper_connector *fb_helper_conn;
        struct drm_display_mode *dmt_mode, *mode;

        /* only contemplate cloning in the single crtc case */
        if (fb_helper->crtc_count > 1)
                return false;

        count = 0;
        for (i = 0; i < fb_helper->connector_count; i++) {
                if (enabled[i])
                        count++;
        }

        /* only contemplate cloning if more than one connector is enabled */
        if (count <= 1)
                return false;

        /* check the command line or if nothing common pick 1024x768 */
        can_clone = true;
        for (i = 0; i < fb_helper->connector_count; i++) {
                if (!enabled[i])
                        continue;
                fb_helper_conn = fb_helper->connector_info[i];
                modes[i] = drm_pick_cmdline_mode(fb_helper_conn, width, height);
                if (!modes[i]) {
                        can_clone = false;
                        break;
                }
                for (j = 0; j < i; j++) {
                        if (!enabled[j])
                                continue;
                        if (!drm_mode_equal(modes[j], modes[i]))
                                can_clone = false;
                }
        }

        if (can_clone) {
                DRM_DEBUG_KMS("can clone using command line\n");
                return true;
        }

        /* try and find a 1024x768 mode on each connector */
        can_clone = true;
        dmt_mode = drm_mode_find_dmt(fb_helper->dev, 1024, 768, 60, false);

        for (i = 0; i < fb_helper->connector_count; i++) {

                if (!enabled[i])
                        continue;

                fb_helper_conn = fb_helper->connector_info[i];
                list_for_each_entry(mode, &fb_helper_conn->connector->modes, head) {
                        if (drm_mode_equal(mode, dmt_mode))
                                modes[i] = mode;
                }
                if (!modes[i])
                        can_clone = false;
        }

        if (can_clone) {
                DRM_DEBUG_KMS("can clone using 1024x768\n");
                return true;
        }
        DRM_INFO("kms: can't enable cloning when we probably wanted to.\n");
        return false;
}

static bool drm_target_preferred(struct drm_fb_helper *fb_helper,
                                 struct drm_display_mode **modes,
                                 bool *enabled, int width, int height)
{
        struct drm_fb_helper_connector *fb_helper_conn;
        int i;

        for (i = 0; i < fb_helper->connector_count; i++) {
                fb_helper_conn = fb_helper->connector_info[i];

                if (enabled[i] == false)
                        continue;

                DRM_DEBUG_KMS("looking for cmdline mode on connector %d\n",
                              fb_helper_conn->connector->base.id);

                /* got for command line mode first */
                modes[i] = drm_pick_cmdline_mode(fb_helper_conn, width, height);
                if (!modes[i]) {
                        DRM_DEBUG_KMS("looking for preferred mode on connector %d\n",
                                      fb_helper_conn->connector->base.id);
                        modes[i] = drm_has_preferred_mode(fb_helper_conn, width, height);
                }
                /* No preferred modes, pick one off the list */
                if (!modes[i] && !list_empty(&fb_helper_conn->connector->modes)) {
                        list_for_each_entry(modes[i], &fb_helper_conn->connector->modes, head)
                                break;
                }
                DRM_DEBUG_KMS("found mode %s\n", modes[i] ? modes[i]->name :
                          "none");
        }
        return true;
}

static int drm_pick_crtcs(struct drm_fb_helper *fb_helper,
                          struct drm_fb_helper_crtc **best_crtcs,
                          struct drm_display_mode **modes,
                          int n, int width, int height)
{
        int c, o;
        struct drm_device *dev = fb_helper->dev;
        struct drm_connector *connector;
        struct drm_connector_helper_funcs *connector_funcs;
        struct drm_encoder *encoder;
        struct drm_fb_helper_crtc *best_crtc;
        int my_score, best_score, score;
        struct drm_fb_helper_crtc **crtcs, *crtc;
        struct drm_fb_helper_connector *fb_helper_conn;

        if (n == fb_helper->connector_count)
                return 0;

        fb_helper_conn = fb_helper->connector_info[n];
        connector = fb_helper_conn->connector;

        best_crtcs[n] = NULL;
        best_crtc = NULL;
        best_score = drm_pick_crtcs(fb_helper, best_crtcs, modes, n+1, width, height);
        if (modes[n] == NULL)
                return best_score;

        crtcs = kzalloc(dev->mode_config.num_connector *
                        sizeof(struct drm_fb_helper_crtc *), GFP_KERNEL);
        if (!crtcs)
                return best_score;

        my_score = 1;
        if (connector->status == connector_status_connected)
                my_score++;
        if (drm_has_cmdline_mode(fb_helper_conn))
                my_score++;
        if (drm_has_preferred_mode(fb_helper_conn, width, height))
                my_score++;

        connector_funcs = connector->helper_private;
        encoder = connector_funcs->best_encoder(connector);
        if (!encoder)
                goto out;

        /* select a crtc for this connector and then attempt to configure
           remaining connectors */
        for (c = 0; c < fb_helper->crtc_count; c++) {
                crtc = &fb_helper->crtc_info[c];

                if ((encoder->possible_crtcs & (1 << c)) == 0)
                        continue;

                for (o = 0; o < n; o++)
                        if (best_crtcs[o] == crtc)
                                break;

                if (o < n) {
                        /* ignore cloning unless only a single crtc */
                        if (fb_helper->crtc_count > 1)
                                continue;

                        if (!drm_mode_equal(modes[o], modes[n]))
                                continue;
                }

                crtcs[n] = crtc;
                memcpy(crtcs, best_crtcs, n * sizeof(struct drm_fb_helper_crtc *));
                score = my_score + drm_pick_crtcs(fb_helper, crtcs, modes, n + 1,
                                                  width, height);
                if (score > best_score) {
                        best_crtc = crtc;
                        best_score = score;
                        memcpy(best_crtcs, crtcs,
                               dev->mode_config.num_connector *
                               sizeof(struct drm_fb_helper_crtc *));
                }
        }
out:
        kfree(crtcs);
        return best_score;
}

static void drm_setup_crtcs(struct drm_fb_helper *fb_helper)
{
        struct drm_device *dev = fb_helper->dev;
        struct drm_fb_helper_crtc **crtcs;
        struct drm_display_mode **modes;
        struct drm_mode_set *modeset;
        bool *enabled;
        int width, height;
        int i, ret;

        DRM_DEBUG_KMS("\n");

        width = dev->mode_config.max_width;
        height = dev->mode_config.max_height;

        crtcs = kcalloc(dev->mode_config.num_connector,
                        sizeof(struct drm_fb_helper_crtc *), GFP_KERNEL);
        modes = kcalloc(dev->mode_config.num_connector,
                        sizeof(struct drm_display_mode *), GFP_KERNEL);
        enabled = kcalloc(dev->mode_config.num_connector,
                          sizeof(bool), GFP_KERNEL);
        if (!crtcs || !modes || !enabled) {
                DRM_ERROR("Memory allocation failed\n");
                goto out;
        }


        drm_enable_connectors(fb_helper, enabled);

        ret = drm_target_cloned(fb_helper, modes, enabled, width, height);
        if (!ret) {
                ret = drm_target_preferred(fb_helper, modes, enabled, width, height);
                if (!ret)
                        DRM_ERROR("Unable to find initial modes\n");
        }

        DRM_DEBUG_KMS("picking CRTCs for %dx%d config\n", width, height);

        drm_pick_crtcs(fb_helper, crtcs, modes, 0, width, height);

        /* need to set the modesets up here for use later */
        /* fill out the connector<->crtc mappings into the modesets */
        for (i = 0; i < fb_helper->crtc_count; i++) {
                modeset = &fb_helper->crtc_info[i].mode_set;
                modeset->num_connectors = 0;
                modeset->fb = NULL;
        }

        for (i = 0; i < fb_helper->connector_count; i++) {
                struct drm_display_mode *mode = modes[i];
                struct drm_fb_helper_crtc *fb_crtc = crtcs[i];
                modeset = &fb_crtc->mode_set;

                if (mode && fb_crtc) {
                        DRM_DEBUG_KMS("desired mode %s set on crtc %d\n",
                                      mode->name, fb_crtc->mode_set.crtc->base.id);
                        fb_crtc->desired_mode = mode;
                        if (modeset->mode)
                                drm_mode_destroy(dev, modeset->mode);
                        modeset->mode = drm_mode_duplicate(dev,
                                                           fb_crtc->desired_mode);
                        modeset->connectors[modeset->num_connectors++] = fb_helper->connector_info[i]->connector;
                        modeset->fb = fb_helper->fb;
                }
        }

        /* Clear out any old modes if there are no more connected outputs. */
        for (i = 0; i < fb_helper->crtc_count; i++) {
                modeset = &fb_helper->crtc_info[i].mode_set;
                if (modeset->num_connectors == 0) {
                        BUG_ON(modeset->fb);
                        BUG_ON(modeset->num_connectors);
                        if (modeset->mode)
                                drm_mode_destroy(dev, modeset->mode);
                        modeset->mode = NULL;
                }
        }
out:
        kfree(crtcs);
        kfree(modes);
        kfree(enabled);
}

/**
 * drm_fb_helper_initial_config - setup a sane initial connector configuration
 * @fb_helper: fb_helper device struct
 * @bpp_sel: bpp value to use for the framebuffer configuration
 *
 * Scans the CRTCs and connectors and tries to put together an initial setup.
 * At the moment, this is a cloned configuration across all heads with
 * a new framebuffer object as the backing store.
 *
 * Note that this also registers the fbdev and so allows userspace to call into
 * the driver through the fbdev interfaces.
 *
 * This function will call down into the ->fb_probe callback to let
 * the driver allocate and initialize the fbdev info structure and the drm
 * framebuffer used to back the fbdev. drm_fb_helper_fill_var() and
 * drm_fb_helper_fill_fix() are provided as helpers to setup simple default
 * values for the fbdev info structure.
 *
 * RETURNS:
 * Zero if everything went ok, nonzero otherwise.
 */
bool drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel)
{
        struct drm_device *dev = fb_helper->dev;
        int count = 0;

        drm_fb_helper_parse_command_line(fb_helper);

        count = drm_fb_helper_probe_connector_modes(fb_helper,
                                                    dev->mode_config.max_width,
                                                    dev->mode_config.max_height);
        /*
         * we shouldn't end up with no modes here.
         */
        if (count == 0)
                dev_info(fb_helper->dev->dev, "No connectors reported connected with modes\n");

        drm_setup_crtcs(fb_helper);

        return drm_fb_helper_single_fb_probe(fb_helper, bpp_sel);
}
EXPORT_SYMBOL(drm_fb_helper_initial_config);

/**
 * drm_fb_helper_hotplug_event - respond to a hotplug notification by
 *                               probing all the outputs attached to the fb
 * @fb_helper: the drm_fb_helper
 *
 * Scan the connectors attached to the fb_helper and try to put together a
 * setup after *notification of a change in output configuration.
 *
 * Called at runtime, takes the mode config locks to be able to check/change the
 * modeset configuration. Must be run from process context (which usually means
 * either the output polling work or a work item launched from the driver's
 * hotplug interrupt).
 *
 * Note that the driver must ensure that this is only called _after_ the fb has
 * been fully set up, i.e. after the call to drm_fb_helper_initial_config.
 *
 * RETURNS:
 * 0 on success and a non-zero error code otherwise.
 */
int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
{
        struct drm_device *dev = fb_helper->dev;
        int count = 0;
        u32 max_width, max_height, bpp_sel;

        if (!fb_helper->fb)
                return 0;

        mutex_lock(&fb_helper->dev->mode_config.mutex);
        if (!drm_fb_helper_is_bound(fb_helper)) {
                fb_helper->delayed_hotplug = true;
                mutex_unlock(&fb_helper->dev->mode_config.mutex);
                return 0;
        }
        DRM_DEBUG_KMS("\n");

        max_width = fb_helper->fb->width;
        max_height = fb_helper->fb->height;
        bpp_sel = fb_helper->fb->bits_per_pixel;

        count = drm_fb_helper_probe_connector_modes(fb_helper, max_width,
                                                    max_height);
        mutex_unlock(&fb_helper->dev->mode_config.mutex);

        drm_modeset_lock_all(dev);
        drm_setup_crtcs(fb_helper);
        drm_modeset_unlock_all(dev);
        drm_fb_helper_set_par(fb_helper->fbdev);

        return 0;
}
EXPORT_SYMBOL(drm_fb_helper_hotplug_event);

/* The Kconfig DRM_KMS_HELPER selects FRAMEBUFFER_CONSOLE (if !EXPERT)
 * but the module doesn't depend on any fb console symbols.  At least
 * attempt to load fbcon to avoid leaving the system without a usable console.
 */
#if defined(CONFIG_FRAMEBUFFER_CONSOLE_MODULE) && !defined(CONFIG_EXPERT)
static int __init drm_fb_helper_modinit(void)
{
        const char *name = "fbcon";
        struct module *fbcon;

        mutex_lock(&module_mutex);
        fbcon = find_module(name);
        mutex_unlock(&module_mutex);

        if (!fbcon)
                request_module_nowait(name);
        return 0;
}

module_init(drm_fb_helper_modinit);
#endif