---

yaml
---
r: 260183
b: refs/heads/master
c: 5a35420
h: refs/heads/master
i:
  260181: df6c535
  260179: 9167310
  260175: dae7fa9
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 9325c9f088c42e3e07475d4f733ee6539ebf9c0b
+refs/heads/master: 5a3542041bf85a65633ed203c3782492116ebb94

trunk/drivers/gpu/drm/i915/intel_display.c

@@ -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)
@@ -4848,64 +4977,46 @@ 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;
 	}
 
 	intel_crtc->fdi_lanes = lane;
 
 	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;

trunk/drivers/gpu/drm/i915/intel_drv.h

@@ -170,6 +170,7 @@ struct intel_crtc {
 	int16_t cursor_x, cursor_y;
 	int16_t cursor_width, cursor_height;
 	bool cursor_visible;
+	unsigned int bpp;
 };
 
 #define to_intel_crtc(x) container_of(x, struct intel_crtc, base)