drm/i915: Disable FBC WM on ILK, and disable LP2+ when FBC is enabled

ILK has a bunch of issues with FBC. First of all, BSpec tells us that
FBC WM should never be enabled. Secondly when FBC is enabled
with FBC WM disabled, LP2+ watermarks must be disabled.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index a65d881..3d4daa1 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2701,7 +2701,8 @@ static void ilk_wm_merge(struct drm_device *dev,
            config->num_pipes_active > 1)
                return;
 
-       merged->fbc_wm_enabled = true;
+       /* ILK: FBC WM must be disabled always */
+       merged->fbc_wm_enabled = INTEL_INFO(dev)->gen >= 6;
 
        /* merge each WM1+ level */
        for (level = 1; level <= max_level; level++) {
@@ -2721,6 +2722,20 @@ static void ilk_wm_merge(struct drm_device *dev,
                        wm->fbc_val = 0;
                }
        }
+
+       /* ILK: LP2+ must be disabled when FBC WM is disabled but FBC enabled */
+       /*
+        * FIXME this is racy. FBC might get enabled later.
+        * What we should check here is whether FBC can be
+        * enabled sometime later.
+        */
+       if (IS_GEN5(dev) && !merged->fbc_wm_enabled && intel_fbc_enabled(dev)) {
+               for (level = 2; level <= max_level; level++) {
+                       struct intel_wm_level *wm = &merged->wm[level];
+
+                       wm->enable = false;
+               }
+       }
 }
 
 static int ilk_wm_lp_to_level(int wm_lp, const struct intel_pipe_wm *pipe_wm)