drm/i915: split out Ironlake pipe bpp picking code
[firefly-linux-kernel-4.4.55.git] / drivers / gpu / drm / i915 / intel_display.c
index ce3666d53f57d82bc720345de08b2426e9351a25..7c5d28fd5f36a89deaf1d3b067c602e7ec3d0a4b 100644 (file)
@@ -4309,6 +4309,133 @@ static inline bool intel_panel_use_ssc(struct drm_i915_private *dev_priv)
        return dev_priv->lvds_use_ssc && i915_panel_use_ssc;
 }
 
+/**
+ * intel_choose_pipe_bpp_dither - figure out what color depth the pipe should send
+ * @crtc: CRTC structure
+ *
+ * A pipe may be connected to one or more outputs.  Based on the depth of the
+ * attached framebuffer, choose a good color depth to use on the pipe.
+ *
+ * If possible, match the pipe depth to the fb depth.  In some cases, this
+ * isn't ideal, because the connected output supports a lesser or restricted
+ * set of depths.  Resolve that here:
+ *    LVDS typically supports only 6bpc, so clamp down in that case
+ *    HDMI supports only 8bpc or 12bpc, so clamp to 8bpc with dither for 10bpc
+ *    Displays may support a restricted set as well, check EDID and clamp as
+ *      appropriate.
+ *
+ * RETURNS:
+ * Dithering requirement (i.e. false if display bpc and pipe bpc match,
+ * true if they don't match).
+ */
+static bool intel_choose_pipe_bpp_dither(struct drm_crtc *crtc,
+                                        unsigned int *pipe_bpp)
+{
+       struct drm_device *dev = crtc->dev;
+       struct drm_i915_private *dev_priv = dev->dev_private;
+       struct drm_encoder *encoder;
+       struct drm_connector *connector;
+       unsigned int display_bpc = UINT_MAX, bpc;
+
+       /* Walk the encoders & connectors on this crtc, get min bpc */
+       list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+               struct intel_encoder *intel_encoder = to_intel_encoder(encoder);
+
+               if (encoder->crtc != crtc)
+                       continue;
+
+               if (intel_encoder->type == INTEL_OUTPUT_LVDS) {
+                       unsigned int lvds_bpc;
+
+                       if ((I915_READ(PCH_LVDS) & LVDS_A3_POWER_MASK) ==
+                           LVDS_A3_POWER_UP)
+                               lvds_bpc = 8;
+                       else
+                               lvds_bpc = 6;
+
+                       if (lvds_bpc < display_bpc) {
+                               DRM_DEBUG_DRIVER("clamping display bpc (was %d) to LVDS (%d)\n", display_bpc, lvds_bpc);
+                               display_bpc = lvds_bpc;
+                       }
+                       continue;
+               }
+
+               if (intel_encoder->type == INTEL_OUTPUT_EDP) {
+                       /* Use VBT settings if we have an eDP panel */
+                       unsigned int edp_bpc = dev_priv->edp.bpp / 3;
+
+                       if (edp_bpc < display_bpc) {
+                               DRM_DEBUG_DRIVER("clamping display bpc (was %d) to eDP (%d)\n", display_bpc, edp_bpc);
+                               display_bpc = edp_bpc;
+                       }
+                       continue;
+               }
+
+               /* Not one of the known troublemakers, check the EDID */
+               list_for_each_entry(connector, &dev->mode_config.connector_list,
+                                   head) {
+                       if (connector->encoder != encoder)
+                               continue;
+
+                       if (connector->display_info.bpc < display_bpc) {
+                               DRM_DEBUG_DRIVER("clamping display bpc (was %d) to EDID reported max of %d\n", display_bpc, connector->display_info.bpc);
+                               display_bpc = connector->display_info.bpc;
+                       }
+               }
+
+               /*
+                * HDMI is either 12 or 8, so if the display lets 10bpc sneak
+                * through, clamp it down.  (Note: >12bpc will be caught below.)
+                */
+               if (intel_encoder->type == INTEL_OUTPUT_HDMI) {
+                       if (display_bpc > 8 && display_bpc < 12) {
+                               DRM_DEBUG_DRIVER("forcing bpc to 12 for HDMI\n");
+                               display_bpc = 12;
+                       } else {
+                               DRM_DEBUG_DRIVER("forcing bpc to 8 for HDMI\n");
+                               display_bpc = 8;
+                       }
+               }
+       }
+
+       /*
+        * We could just drive the pipe at the highest bpc all the time and
+        * enable dithering as needed, but that costs bandwidth.  So choose
+        * the minimum value that expresses the full color range of the fb but
+        * also stays within the max display bpc discovered above.
+        */
+
+       switch (crtc->fb->depth) {
+       case 8:
+               bpc = 8; /* since we go through a colormap */
+               break;
+       case 15:
+       case 16:
+               bpc = 6; /* min is 18bpp */
+               break;
+       case 24:
+               bpc = min((unsigned int)8, display_bpc);
+               break;
+       case 30:
+               bpc = min((unsigned int)10, display_bpc);
+               break;
+       case 48:
+               bpc = min((unsigned int)12, display_bpc);
+               break;
+       default:
+               DRM_DEBUG("unsupported depth, assuming 24 bits\n");
+               bpc = min((unsigned int)8, display_bpc);
+               break;
+       }
+
+       DRM_DEBUG_DRIVER("setting pipe bpc to %d (max display bpc %d)\n",
+                        bpc, display_bpc);
+
+       *pipe_bpp = bpc * 3;
+
+       return display_bpc != bpc;
+}
+
 static int i9xx_crtc_mode_set(struct drm_crtc *crtc,
                              struct drm_display_mode *mode,
                              struct drm_display_mode *adjusted_mode,
@@ -4721,7 +4848,9 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
        struct fdi_m_n m_n = {0};
        u32 temp;
        u32 lvds_sync = 0;
-       int target_clock, pixel_multiplier, lane, link_bw, bpp, factor;
+       int target_clock, pixel_multiplier, lane, link_bw, factor;
+       unsigned int pipe_bpp;
+       bool dither;
 
        list_for_each_entry(encoder, &mode_config->encoder_list, base.head) {
                if (encoder->base.crtc != crtc)
@@ -4848,56 +4977,37 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
        /* determine panel color depth */
        temp = I915_READ(PIPECONF(pipe));
        temp &= ~PIPE_BPC_MASK;
-       if (is_lvds) {
-               /* the BPC will be 6 if it is 18-bit LVDS panel */
-               if ((I915_READ(PCH_LVDS) & LVDS_A3_POWER_MASK) == LVDS_A3_POWER_UP)
-                       temp |= PIPE_8BPC;
-               else
-                       temp |= PIPE_6BPC;
-       } else if (has_edp_encoder) {
-               switch (dev_priv->edp.bpp/3) {
-               case 8:
-                       temp |= PIPE_8BPC;
-                       break;
-               case 10:
-                       temp |= PIPE_10BPC;
-                       break;
-               case 6:
-                       temp |= PIPE_6BPC;
-                       break;
-               case 12:
-                       temp |= PIPE_12BPC;
-                       break;
-               }
-       } else
-               temp |= PIPE_8BPC;
-       I915_WRITE(PIPECONF(pipe), temp);
-
-       switch (temp & PIPE_BPC_MASK) {
-       case PIPE_8BPC:
-               bpp = 24;
+       dither = intel_choose_pipe_bpp_dither(crtc, &pipe_bpp);
+       switch (pipe_bpp) {
+       case 18:
+               temp |= PIPE_6BPC;
                break;
-       case PIPE_10BPC:
-               bpp = 30;
+       case 24:
+               temp |= PIPE_8BPC;
                break;
-       case PIPE_6BPC:
-               bpp = 18;
+       case 30:
+               temp |= PIPE_10BPC;
                break;
-       case PIPE_12BPC:
-               bpp = 36;
+       case 36:
+               temp |= PIPE_12BPC;
                break;
        default:
-               DRM_ERROR("unknown pipe bpc value\n");
-               bpp = 24;
+               WARN(1, "intel_choose_pipe_bpp returned invalid value\n");
+               temp |= PIPE_8BPC;
+               pipe_bpp = 24;
+               break;
        }
 
+       intel_crtc->bpp = pipe_bpp;
+       I915_WRITE(PIPECONF(pipe), temp);
+
        if (!lane) {
                /*
                 * Account for spread spectrum to avoid
                 * oversubscribing the link. Max center spread
                 * is 2.5%; use 5% for safety's sake.
                 */
-               u32 bps = target_clock * bpp * 21 / 20;
+               u32 bps = target_clock * intel_crtc->bpp * 21 / 20;
                lane = bps / (link_bw * 8) + 1;
        }
 
@@ -4905,7 +5015,8 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
 
        if (pixel_multiplier > 1)
                link_bw *= pixel_multiplier;
-       ironlake_compute_m_n(bpp, lane, target_clock, link_bw, &m_n);
+       ironlake_compute_m_n(intel_crtc->bpp, lane, target_clock, link_bw,
+                            &m_n);
 
        /* Ironlake: try to setup display ref clock before DPLL
         * enabling. This is only under driver's control after
@@ -5108,14 +5219,12 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
                I915_WRITE(PCH_LVDS, temp);
        }
 
-       /* set the dithering flag and clear for anything other than a panel. */
        pipeconf &= ~PIPECONF_DITHER_EN;
        pipeconf &= ~PIPECONF_DITHER_TYPE_MASK;
-       if (dev_priv->lvds_dither && (is_lvds || has_edp_encoder)) {
+       if ((is_lvds && dev_priv->lvds_dither) || dither) {
                pipeconf |= PIPECONF_DITHER_EN;
                pipeconf |= PIPECONF_DITHER_TYPE_ST1;
        }
-
        if (is_dp || intel_encoder_is_pch_edp(&has_edp_encoder->base)) {
                intel_dp_set_m_n(crtc, mode, adjusted_mode);
        } else {
@@ -6638,6 +6747,7 @@ static void intel_crtc_init(struct drm_device *dev, int pipe)
 
        intel_crtc_reset(&intel_crtc->base);
        intel_crtc->active = true; /* force the pipe off on setup_init_config */
+       intel_crtc->bpp = 24; /* default for pre-Ironlake */
 
        if (HAS_PCH_SPLIT(dev)) {
                intel_helper_funcs.prepare = ironlake_crtc_prepare;