drm/i915/gen9: Add WaFbcTurnOffFbcWatermark

According to bspec this prevents screen corruption when fbc is
used.

v2: This workaround has a name, use it (Ville)
v3: remove bogus gen check on ilk/vlv wm path (Ville)

References: HSD#2135555, HSD#2137270, BSID#562
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1465309159-30531-25-git-send-email-mika.kuoppala@intel.com

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index d766d1a..de3dd24 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -69,6 +69,10 @@ static void gen9_init_clock_gating(struct drm_device *dev)
        /* WaEnableChickenDCPR:skl,bxt,kbl */
        I915_WRITE(GEN8_CHICKEN_DCPR_1,
                   I915_READ(GEN8_CHICKEN_DCPR_1) | MASK_WAKEMEM);
+
+       /* WaFbcTurnOffFbcWatermark:skl,bxt,kbl */
+       I915_WRITE(DISP_ARB_CTL,
+                  I915_READ(DISP_ARB_CTL) | DISP_FBC_WM_DIS);
 }
 
 static void bxt_init_clock_gating(struct drm_device *dev)