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 <ville.syrjala@linux.intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 16 insertions, 25 deletions

diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
index e3e9c98eaf52..4a876914f212 100644
--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/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);
 	}
 }