drm/i915: implement the Haswell mode set sequence workaround

This workaround is described in the mode set sequence documentation.
When enabling planes for the second pipe, we need to wait for 2
vblanks on the first pipe. This should solve "a flash of screen
corruption if planes are enabled on second/third pipe during the time
that big FIFO mode is exiting". Watermarks are fun :)

v2: Save indentation levels

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 521df12..26b8392 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3494,6 +3494,35 @@ static void haswell_crtc_disable_planes(struct drm_crtc *crtc)
        intel_disable_plane(dev_priv, plane, pipe);
 }
 
+/*
+ * This implements the workaround described in the "notes" section of the mode
+ * set sequence documentation. When going from no pipes or single pipe to
+ * multiple pipes, and planes are enabled after the pipe, we need to wait at
+ * least 2 vblanks on the first pipe before enabling planes on the second pipe.
+ */
+static void haswell_mode_set_planes_workaround(struct intel_crtc *crtc)
+{
+       struct drm_device *dev = crtc->base.dev;
+       struct intel_crtc *crtc_it, *other_active_crtc = NULL;
+
+       /* We want to get the other_active_crtc only if there's only 1 other
+        * active crtc. */
+       list_for_each_entry(crtc_it, &dev->mode_config.crtc_list, base.head) {
+               if (!crtc_it->active || crtc_it == crtc)
+                       continue;
+
+               if (other_active_crtc)
+                       return;
+
+               other_active_crtc = crtc_it;
+       }
+       if (!other_active_crtc)
+               return;
+
+       intel_wait_for_vblank(dev, other_active_crtc->pipe);
+       intel_wait_for_vblank(dev, other_active_crtc->pipe);
+}
+
 static void haswell_crtc_enable(struct drm_crtc *crtc)
 {
        struct drm_device *dev = crtc->dev;
@@ -3545,6 +3574,9 @@ static void haswell_crtc_enable(struct drm_crtc *crtc)
                intel_opregion_notify_encoder(encoder, true);
        }
 
+       /* If we change the relative order between pipe/planes enabling, we need
+        * to change the workaround. */
+       haswell_mode_set_planes_workaround(intel_crtc);
        haswell_crtc_enable_planes(crtc);
 
        /*