drm: mxsfb: use bus_format to determine LCD bus width

The LCD bus width does not need to align with the pixel format. The
LCDIF controller automatically converts between pixel formats and
bus width by padding or dropping LSBs.

The DRM subsystem has the notion of bus_format which allows to
determine what bus_formats are supported by the display. Choose the
first available or fallback to 24 bit if none are available.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
index e10a4eda4078ba9b211ca49530da2b659865c8ee..259f71b3a76ac53fb6c7b4ab6f6034a559b25a95 100644 (file)
--- a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
@@ -65,13 +65,11 @@ static int mxsfb_set_pixel_fmt(struct mxsfb_drm_private *mxsfb)
        switch (format) {
        case DRM_FORMAT_RGB565:
                dev_dbg(drm->dev, "Setting up RGB565 mode\n");
-               ctrl |= CTRL_SET_BUS_WIDTH(STMLCDIF_16BIT);
                ctrl |= CTRL_SET_WORD_LENGTH(0);
                ctrl1 |= CTRL1_SET_BYTE_PACKAGING(0xf);
                break;
        case DRM_FORMAT_XRGB8888:
                dev_dbg(drm->dev, "Setting up XRGB8888 mode\n");
-               ctrl |= CTRL_SET_BUS_WIDTH(STMLCDIF_24BIT);
                ctrl |= CTRL_SET_WORD_LENGTH(3);
                /* Do not use packed pixels = one pixel per word instead. */
                ctrl1 |= CTRL1_SET_BYTE_PACKAGING(0x7);
@@ -87,6 +85,36 @@ static int mxsfb_set_pixel_fmt(struct mxsfb_drm_private *mxsfb)
        return 0;
 }
 
+static void mxsfb_set_bus_fmt(struct mxsfb_drm_private *mxsfb)
+{
+       struct drm_crtc *crtc = &mxsfb->pipe.crtc;
+       struct drm_device *drm = crtc->dev;
+       u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24;
+       u32 reg;
+
+       reg = readl(mxsfb->base + LCDC_CTRL);
+
+       if (mxsfb->connector.display_info.num_bus_formats)
+               bus_format = mxsfb->connector.display_info.bus_formats[0];
+
+       reg &= ~CTRL_BUS_WIDTH_MASK;
+       switch (bus_format) {
+       case MEDIA_BUS_FMT_RGB565_1X16:
+               reg |= CTRL_SET_BUS_WIDTH(STMLCDIF_16BIT);
+               break;
+       case MEDIA_BUS_FMT_RGB666_1X18:
+               reg |= CTRL_SET_BUS_WIDTH(STMLCDIF_18BIT);
+               break;
+       case MEDIA_BUS_FMT_RGB888_1X24:
+               reg |= CTRL_SET_BUS_WIDTH(STMLCDIF_24BIT);
+               break;
+       default:
+               dev_err(drm->dev, "Unknown media bus format %d\n", bus_format);
+               break;
+       }
+       writel(reg, mxsfb->base + LCDC_CTRL);
+}
+
 static void mxsfb_enable_controller(struct mxsfb_drm_private *mxsfb)
 {
        u32 reg;
@@ -175,6 +203,8 @@ static void mxsfb_crtc_mode_set_nofb(struct mxsfb_drm_private *mxsfb)
 
        writel(vdctrl0, mxsfb->base + LCDC_VDCTRL0);
 
+       mxsfb_set_bus_fmt(mxsfb);
+
        /* Frame length in lines. */
        writel(m->crtc_vtotal, mxsfb->base + LCDC_VDCTRL1);
 

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_regs.h b/drivers/gpu/drm/mxsfb/mxsfb_regs.h
index 31d62cd0d3d78abe465559992ea75f8dd988ff22..66a6ba9ec533ffe96c04915937bd6b8fba68a1b0 100644 (file)
--- a/drivers/gpu/drm/mxsfb/mxsfb_regs.h
+++ b/drivers/gpu/drm/mxsfb/mxsfb_regs.h
@@ -44,6 +44,7 @@
 #define CTRL_DATA_SELECT               (1 << 16)
 #define CTRL_SET_BUS_WIDTH(x)          (((x) & 0x3) << 10)
 #define CTRL_GET_BUS_WIDTH(x)          (((x) >> 10) & 0x3)
+#define CTRL_BUS_WIDTH_MASK            (0x3 << 10)
 #define CTRL_SET_WORD_LENGTH(x)                (((x) & 0x3) << 8)
 #define CTRL_GET_WORD_LENGTH(x)                (((x) >> 8) & 0x3)
 #define CTRL_MASTER                    (1 << 5)