drivers/gpu/drm/i915/intel_dp_aux_backlight.c

   1 /*
   2  * Copyright © 2015 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  *
  23  */
  24
  25 #include "intel_drv.h"
  26
  27 static void set_aux_backlight_enable(struct intel_dp *intel_dp, bool enable)
  28 {
  29         uint8_t reg_val = 0;
  30
  31         /* Early return when display use other mechanism to enable backlight. */
  32         if (!(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP))
  33                 return;
  34
  35         if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
  36                               &reg_val) < 0) {
  37                 DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
  38                               DP_EDP_DISPLAY_CONTROL_REGISTER);
  39                 return;
  40         }
  41         if (enable)
  42                 reg_val |= DP_EDP_BACKLIGHT_ENABLE;
  43         else
  44                 reg_val &= ~(DP_EDP_BACKLIGHT_ENABLE);
  45
  46         if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
  47                                reg_val) != 1) {
  48                 DRM_DEBUG_KMS("Failed to %s aux backlight\n",
  49                               enable ? "enable" : "disable");
  50         }
  51 }
  52
  53 /*
  54  * Read the current backlight value from DPCD register(s) based
  55  * on if 8-bit(MSB) or 16-bit(MSB and LSB) values are supported
  56  */
  57 static uint32_t intel_dp_aux_get_backlight(struct intel_connector *connector)
  58 {
  59         struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
  60         uint8_t read_val[2] = { 0x0 };
  61         uint16_t level = 0;
  62
  63         if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
  64                              &read_val, sizeof(read_val)) < 0) {
  65                 DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
  66                               DP_EDP_BACKLIGHT_BRIGHTNESS_MSB);
  67                 return 0;
  68         }
  69         level = read_val[0];
  70         if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
  71                 level = (read_val[0] << 8 | read_val[1]);
  72
  73         return level;
  74 }
  75
  76 /*
  77  * Sends the current backlight level over the aux channel, checking if its using
  78  * 8-bit or 16 bit value (MSB and LSB)
  79  */
  80 static void
  81 intel_dp_aux_set_backlight(const struct drm_connector_state *conn_state, u32 level)
  82 {
  83         struct intel_connector *connector = to_intel_connector(conn_state->connector);
  84         struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
  85         uint8_t vals[2] = { 0x0 };
  86
  87         vals[0] = level;
  88
  89         /* Write the MSB and/or LSB */
  90         if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT) {
  91                 vals[0] = (level & 0xFF00) >> 8;
  92                 vals[1] = (level & 0xFF);
  93         }
  94         if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
  95                               vals, sizeof(vals)) < 0) {
  96                 DRM_DEBUG_KMS("Failed to write aux backlight level\n");
  97                 return;
  98         }
  99 }
 100
 101 /*
 102  * Set PWM Frequency divider to match desired frequency in vbt.
 103  * The PWM Frequency is calculated as 27Mhz / (F x P).
 104  * - Where F = PWM Frequency Pre-Divider value programmed by field 7:0 of the
 105  *             EDP_BACKLIGHT_FREQ_SET register (DPCD Address 00728h)
 106  * - Where P = 2^Pn, where Pn is the value programmed by field 4:0 of the
 107  *             EDP_PWMGEN_BIT_COUNT register (DPCD Address 00724h)
 108  */
 109 static bool intel_dp_aux_set_pwm_freq(struct intel_connector *connector)
 110 {
 111         struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
 112         struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
 113         int freq, fxp, fxp_min, fxp_max, fxp_actual, f = 1;
 114         u8 pn, pn_min, pn_max;
 115
 116         /* Find desired value of (F x P)
 117          * Note that, if F x P is out of supported range, the maximum value or
 118          * minimum value will applied automatically. So no need to check that.
 119          */
 120         freq = dev_priv->vbt.backlight.pwm_freq_hz;
 121         DRM_DEBUG_KMS("VBT defined backlight frequency %u Hz\n", freq);
 122         if (!freq) {
 123                 DRM_DEBUG_KMS("Use panel default backlight frequency\n");
 124                 return false;
 125         }
 126
 127         fxp = DIV_ROUND_CLOSEST(KHz(DP_EDP_BACKLIGHT_FREQ_BASE_KHZ), freq);
 128
 129         /* Use highest possible value of Pn for more granularity of brightness
 130          * adjustment while satifying the conditions below.
 131          * - Pn is in the range of Pn_min and Pn_max
 132          * - F is in the range of 1 and 255
 133          * - FxP is within 25% of desired value.
 134          *   Note: 25% is arbitrary value and may need some tweak.
 135          */
 136         if (drm_dp_dpcd_readb(&intel_dp->aux,
 137                                DP_EDP_PWMGEN_BIT_COUNT_CAP_MIN, &pn_min) != 1) {
 138                 DRM_DEBUG_KMS("Failed to read pwmgen bit count cap min\n");
 139                 return false;
 140         }
 141         if (drm_dp_dpcd_readb(&intel_dp->aux,
 142                                DP_EDP_PWMGEN_BIT_COUNT_CAP_MAX, &pn_max) != 1) {
 143                 DRM_DEBUG_KMS("Failed to read pwmgen bit count cap max\n");
 144                 return false;
 145         }
 146         pn_min &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
 147         pn_max &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
 148
 149         fxp_min = DIV_ROUND_CLOSEST(fxp * 3, 4);
 150         fxp_max = DIV_ROUND_CLOSEST(fxp * 5, 4);
 151         if (fxp_min < (1 << pn_min) || (255 << pn_max) < fxp_max) {
 152                 DRM_DEBUG_KMS("VBT defined backlight frequency out of range\n");
 153                 return false;
 154         }
 155
 156         for (pn = pn_max; pn >= pn_min; pn--) {
 157                 f = clamp(DIV_ROUND_CLOSEST(fxp, 1 << pn), 1, 255);
 158                 fxp_actual = f << pn;
 159                 if (fxp_min <= fxp_actual && fxp_actual <= fxp_max)
 160                         break;
 161         }
 162
 163         if (drm_dp_dpcd_writeb(&intel_dp->aux,
 164                                DP_EDP_PWMGEN_BIT_COUNT, pn) < 0) {
 165                 DRM_DEBUG_KMS("Failed to write aux pwmgen bit count\n");
 166                 return false;
 167         }
 168         if (drm_dp_dpcd_writeb(&intel_dp->aux,
 169                                DP_EDP_BACKLIGHT_FREQ_SET, (u8) f) < 0) {
 170                 DRM_DEBUG_KMS("Failed to write aux backlight freq\n");
 171                 return false;
 172         }
 173         return true;
 174 }
 175
 176 static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_state,
 177                                           const struct drm_connector_state *conn_state)
 178 {
 179         struct intel_connector *connector = to_intel_connector(conn_state->connector);
 180         struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
 181         uint8_t dpcd_buf, new_dpcd_buf, edp_backlight_mode;
 182
 183         if (drm_dp_dpcd_readb(&intel_dp->aux,
 184                         DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf) != 1) {
 185                 DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
 186                               DP_EDP_BACKLIGHT_MODE_SET_REGISTER);
 187                 return;
 188         }
 189
 190         new_dpcd_buf = dpcd_buf;
 191         edp_backlight_mode = dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
 192
 193         switch (edp_backlight_mode) {
 194         case DP_EDP_BACKLIGHT_CONTROL_MODE_PWM:
 195         case DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET:
 196         case DP_EDP_BACKLIGHT_CONTROL_MODE_PRODUCT:
 197                 new_dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
 198                 new_dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
 199                 break;
 200
 201         /* Do nothing when it is already DPCD mode */
 202         case DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD:
 203         default:
 204                 break;
 205         }
 206
 207         if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP)
 208                 if (intel_dp_aux_set_pwm_freq(connector))
 209                         new_dpcd_buf |= DP_EDP_BACKLIGHT_FREQ_AUX_SET_ENABLE;
 210
 211         if (new_dpcd_buf != dpcd_buf) {
 212                 if (drm_dp_dpcd_writeb(&intel_dp->aux,
 213                         DP_EDP_BACKLIGHT_MODE_SET_REGISTER, new_dpcd_buf) < 0) {
 214                         DRM_DEBUG_KMS("Failed to write aux backlight mode\n");
 215                 }
 216         }
 217
 218         set_aux_backlight_enable(intel_dp, true);
 219         intel_dp_aux_set_backlight(conn_state, connector->panel.backlight.level);
 220 }
 221
 222 static void intel_dp_aux_disable_backlight(const struct drm_connector_state *old_conn_state)
 223 {
 224         set_aux_backlight_enable(enc_to_intel_dp(old_conn_state->best_encoder), false);
 225 }
 226
 227 static int intel_dp_aux_setup_backlight(struct intel_connector *connector,
 228                                         enum pipe pipe)
 229 {
 230         struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
 231         struct intel_panel *panel = &connector->panel;
 232
 233         if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
 234                 panel->backlight.max = 0xFFFF;
 235         else
 236                 panel->backlight.max = 0xFF;
 237
 238         panel->backlight.min = 0;
 239         panel->backlight.level = intel_dp_aux_get_backlight(connector);
 240
 241         panel->backlight.enabled = panel->backlight.level != 0;
 242
 243         return 0;
 244 }
 245
 246 static bool
 247 intel_dp_aux_display_control_capable(struct intel_connector *connector)
 248 {
 249         struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
 250
 251         /* Check the eDP Display control capabilities registers to determine if
 252          * the panel can support backlight control over the aux channel
 253          */
 254         if ((intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP) &&
 255             (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP)) {
 256                 DRM_DEBUG_KMS("AUX Backlight Control Supported!\n");
 257                 return true;
 258         }
 259         return false;
 260 }
 261
 262 /*
 263  * Heuristic function whether we should use AUX for backlight adjustment or not.
 264  *
 265  * We should use AUX for backlight brightness adjustment if panel doesn't this
 266  * via PWM pin or using AUX is better than using PWM pin.
 267  *
 268  * The heuristic to determine that using AUX pin is better than using PWM pin is
 269  * that the panel support any of the feature list here.
 270  * - Regional backlight brightness adjustment
 271  * - Backlight PWM frequency set
 272  * - More than 8 bits resolution of brightness level
 273  * - Backlight enablement via AUX and not by BL_ENABLE pin
 274  *
 275  * If all above are not true, assume that using PWM pin is better.
 276  */
 277 static bool
 278 intel_dp_aux_display_control_heuristic(struct intel_connector *connector)
 279 {
 280         struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
 281         uint8_t reg_val;
 282
 283         /* Panel doesn't support adjusting backlight brightness via PWN pin */
 284         if (!(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP))
 285                 return true;
 286
 287         /* Panel supports regional backlight brightness adjustment */
 288         if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_GENERAL_CAP_3,
 289                               &reg_val) != 1) {
 290                 DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
 291                                DP_EDP_GENERAL_CAP_3);
 292                 return false;
 293         }
 294         if (reg_val > 0)
 295                 return true;
 296
 297         /* Panel supports backlight PWM frequency set */
 298         if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP)
 299                 return true;
 300
 301         /* Panel supports more than 8 bits resolution of brightness level */
 302         if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
 303                 return true;
 304
 305         /* Panel supports enabling backlight via AUX but not by BL_ENABLE pin */
 306         if ((intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
 307             !(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_PIN_ENABLE_CAP))
 308                 return true;
 309
 310         return false;
 311
 312 }
 313
 314 int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
 315 {
 316         struct intel_panel *panel = &intel_connector->panel;
 317
 318         if (!i915.enable_dpcd_backlight)
 319                 return -ENODEV;
 320
 321         if (!intel_dp_aux_display_control_capable(intel_connector))
 322                 return -ENODEV;
 323
 324         if (i915.enable_dpcd_backlight == -1 &&
 325             !intel_dp_aux_display_control_heuristic(intel_connector))
 326                 return -ENODEV;
 327
 328         panel->backlight.setup = intel_dp_aux_setup_backlight;
 329         panel->backlight.enable = intel_dp_aux_enable_backlight;
 330         panel->backlight.disable = intel_dp_aux_disable_backlight;
 331         panel->backlight.set = intel_dp_aux_set_backlight;
 332         panel->backlight.get = intel_dp_aux_get_backlight;
 333
 334         return 0;
 335 }