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, 23 insertions, 27 deletions

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index d148e09db901..fb2dc84e1061 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/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)