drm/i915: Fix the IBX transcoder B workarounds

Currently the IBX transcoder B workarounds are not working correctly.
Well, the HDMI one seems to be working somewhat, but the DP one is
definitely busted.

After a bit of experimentation it looks like the best way to make this
work is first disable the port on transcoder B, and then re-enable it
transcoder A, and immediately disable it again.

We can also clean up the code by noting that we can't be called without
a valid crtc. And also note that port A on ILK does not need the
workaround, so let's check for that one too.

Signed-off-by: Ville Syrjälä <[email protected]>
Reviewed-by: Jesse Barnes <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>

Author: vsyrjala

drivers/gpu/drm/i915/intel_dp.c

@@ -3843,6 +3843,7 @@ static void
 intel_dp_link_down(struct intel_dp *intel_dp)
 {
 	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
+	struct intel_crtc *crtc = to_intel_crtc(intel_dig_port->base.base.crtc);
 	enum port port = intel_dig_port->port;
 	struct drm_device *dev = intel_dig_port->base.base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -3859,34 +3860,38 @@ intel_dp_link_down(struct intel_dp *intel_dp)
 	if ((IS_GEN7(dev) && port == PORT_A) ||
 	    (HAS_PCH_CPT(dev) && port != PORT_A)) {
 		DP &= ~DP_LINK_TRAIN_MASK_CPT;
-		I915_WRITE(intel_dp->output_reg, DP | DP_LINK_TRAIN_PAT_IDLE_CPT);
+		DP |= DP_LINK_TRAIN_PAT_IDLE_CPT;
 	} else {
 		if (IS_CHERRYVIEW(dev))
 			DP &= ~DP_LINK_TRAIN_MASK_CHV;
 		else
 			DP &= ~DP_LINK_TRAIN_MASK;
-		I915_WRITE(intel_dp->output_reg, DP | DP_LINK_TRAIN_PAT_IDLE);
+		DP |= DP_LINK_TRAIN_PAT_IDLE;
 	}
+	I915_WRITE(intel_dp->output_reg, DP);
 	POSTING_READ(intel_dp->output_reg);
 
-	if (HAS_PCH_IBX(dev) &&
-	    I915_READ(intel_dp->output_reg) & DP_PIPEB_SELECT) {
-		/* Hardware workaround: leaving our transcoder select
-		 * set to transcoder B while it's off will prevent the
-		 * corresponding HDMI output on transcoder A.
-		 *
-		 * Combine this with another hardware workaround:
-		 * transcoder select bit can only be cleared while the
-		 * port is enabled.
-		 */
-		DP &= ~DP_PIPEB_SELECT;
+	DP &= ~(DP_PORT_EN | DP_AUDIO_OUTPUT_ENABLE);
+	I915_WRITE(intel_dp->output_reg, DP);
+	POSTING_READ(intel_dp->output_reg);
+
+	/*
+	 * HW workaround for IBX, we need to move the port
+	 * to transcoder A after disabling it to allow the
+	 * matching HDMI port to be enabled on transcoder A.
+	 */
+	if (HAS_PCH_IBX(dev) && crtc->pipe == PIPE_B && port != PORT_A) {
+		/* always enable with pattern 1 (as per spec) */
+		DP &= ~(DP_PIPEB_SELECT | DP_LINK_TRAIN_MASK);
+		DP |= DP_PORT_EN | DP_LINK_TRAIN_PAT_1;
+		I915_WRITE(intel_dp->output_reg, DP);
+		POSTING_READ(intel_dp->output_reg);
+
+		DP &= ~DP_PORT_EN;
 		I915_WRITE(intel_dp->output_reg, DP);
 		POSTING_READ(intel_dp->output_reg);
 	}
 
-	DP &= ~DP_AUDIO_OUTPUT_ENABLE;
-	I915_WRITE(intel_dp->output_reg, DP & ~DP_PORT_EN);
-	POSTING_READ(intel_dp->output_reg);
 	msleep(intel_dp->panel_power_down_delay);
 }
 

drivers/gpu/drm/i915/intel_hdmi.c

@@ -873,41 +873,37 @@ static void intel_disable_hdmi(struct intel_encoder *encoder)
 	struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(&encoder->base);
 	struct intel_crtc *crtc = to_intel_crtc(encoder->base.crtc);
 	u32 temp;
-	u32 enable_bits = SDVO_ENABLE | SDVO_AUDIO_ENABLE;
 
 	if (crtc->config->has_audio)
 		intel_audio_codec_disable(encoder);
 
 	temp = I915_READ(intel_hdmi->hdmi_reg);
 
-	/* HW workaround for IBX, we need to move the port to transcoder A
-	 * before disabling it. */
-	if (HAS_PCH_IBX(dev)) {
-		struct drm_crtc *crtc = encoder->base.crtc;
-		int pipe = crtc ? to_intel_crtc(crtc)->pipe : -1;
-
-		if (temp & SDVO_PIPE_B_SELECT) {
-			temp &= ~SDVO_PIPE_B_SELECT;
-			I915_WRITE(intel_hdmi->hdmi_reg, temp);
-			POSTING_READ(intel_hdmi->hdmi_reg);
-
-			/* Again we need to write this twice. */
-			I915_WRITE(intel_hdmi->hdmi_reg, temp);
-			POSTING_READ(intel_hdmi->hdmi_reg);
-
-			/* Transcoder selection bits only update
-			 * effectively on vblank. */
-			if (crtc)
-				intel_wait_for_vblank(dev, pipe);
-			else
-				msleep(50);
-		}
-	}
-
-	temp &= ~enable_bits;
-
+	temp &= ~(SDVO_ENABLE | SDVO_AUDIO_ENABLE);
 	I915_WRITE(intel_hdmi->hdmi_reg, temp);
 	POSTING_READ(intel_hdmi->hdmi_reg);
+
+	/*
+	 * HW workaround for IBX, we need to move the port
+	 * to transcoder A after disabling it to allow the
+	 * matching DP port to be enabled on transcoder A.
+	 */
+	if (HAS_PCH_IBX(dev) && crtc->pipe == PIPE_B) {
+		temp &= ~SDVO_PIPE_B_SELECT;
+		temp |= SDVO_ENABLE;
+		/*
+		 * HW workaround, need to write this twice for issue
+		 * that may result in first write getting masked.
+		 */
+		I915_WRITE(intel_hdmi->hdmi_reg, temp);
+		POSTING_READ(intel_hdmi->hdmi_reg);
+		I915_WRITE(intel_hdmi->hdmi_reg, temp);
+		POSTING_READ(intel_hdmi->hdmi_reg);
+
+		temp &= ~SDVO_ENABLE;
+		I915_WRITE(intel_hdmi->hdmi_reg, temp);
+		POSTING_READ(intel_hdmi->hdmi_reg);
+	}
 }
 
 static int hdmi_portclock_limit(struct intel_hdmi *hdmi, bool respect_dvi_limit)

drivers/gpu/drm/i915/intel_sdvo.c

@@ -1437,6 +1437,7 @@ static void intel_disable_sdvo(struct intel_encoder *encoder)
 {
 	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
 	struct intel_sdvo *intel_sdvo = to_sdvo(encoder);
+	struct intel_crtc *crtc = to_intel_crtc(encoder->base.crtc);
 	u32 temp;
 
 	intel_sdvo_set_active_outputs(intel_sdvo, 0);
@@ -1445,32 +1446,22 @@ static void intel_disable_sdvo(struct intel_encoder *encoder)
 						   DRM_MODE_DPMS_OFF);
 
 	temp = I915_READ(intel_sdvo->sdvo_reg);
-	if ((temp & SDVO_ENABLE) != 0) {
-		/* HW workaround for IBX, we need to move the port to
-		 * transcoder A before disabling it. */
-		if (HAS_PCH_IBX(encoder->base.dev)) {
-			struct drm_crtc *crtc = encoder->base.crtc;
-			int pipe = crtc ? to_intel_crtc(crtc)->pipe : -1;
-
-			if (temp & SDVO_PIPE_B_SELECT) {
-				temp &= ~SDVO_PIPE_B_SELECT;
-				I915_WRITE(intel_sdvo->sdvo_reg, temp);
-				POSTING_READ(intel_sdvo->sdvo_reg);
-
-				/* Again we need to write this twice. */
-				I915_WRITE(intel_sdvo->sdvo_reg, temp);
-				POSTING_READ(intel_sdvo->sdvo_reg);
-
-				/* Transcoder selection bits only update
-				 * effectively on vblank. */
-				if (crtc)
-					intel_wait_for_vblank(encoder->base.dev, pipe);
-				else
-					msleep(50);
-			}
-		}
 
-		intel_sdvo_write_sdvox(intel_sdvo, temp & ~SDVO_ENABLE);
+	temp &= ~SDVO_ENABLE;
+	intel_sdvo_write_sdvox(intel_sdvo, temp);
+
+	/*
+	 * HW workaround for IBX, we need to move the port
+	 * to transcoder A after disabling it to allow the
+	 * matching DP port to be enabled on transcoder A.
+	 */
+	if (HAS_PCH_IBX(dev_priv) && crtc->pipe == PIPE_B) {
+		temp &= ~SDVO_PIPE_B_SELECT;
+		temp |= SDVO_ENABLE;
+		intel_sdvo_write_sdvox(intel_sdvo, temp);
+
+		temp &= ~SDVO_ENABLE;
+		intel_sdvo_write_sdvox(intel_sdvo, temp);
 	}
 }