drm/i915: Use mmio flips to change tiling mode on Baytrail

For whatever reason, MI_DISPLAY_FLIP fails to change tiling mode on
Baytrail, so just use CPU driven mmio flips instead.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76176
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 8728c8885339..8e738d4315a8 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9435,6 +9435,9 @@ static bool use_mmio_flip(struct intel_engine_cs *ring,
          * So using MMIO flips there would disrupt this mechanism.
          */
 
+        if (ring == NULL)
+                return true;
+
         if (INTEL_INFO(ring->dev)->gen < 5)
                 return false;
 
@@ -9658,6 +9661,9 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 
         if (IS_VALLEYVIEW(dev)) {
                 ring = &dev_priv->ring[BCS];
+                if (obj->tiling_mode != work->old_fb_obj->tiling_mode)
+                        /* vlv: DISPLAY_FLIP fails to change tiling */
+                        ring = NULL;
         } else if (IS_IVYBRIDGE(dev)) {
                 ring = &dev_priv->ring[BCS];
         } else if (INTEL_INFO(dev)->gen >= 7) {