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);
         }
 }