[Intel-gfx] [PATCH 21/23] drm/i915/gen9: Add WaFbcTurnOffFbcWatermark

[Mika Kuoppala]

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

v2: This workaround has a name, use it (Ville)

References: HSD#2135555, HSD#2137270, BSID#562
Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 2da09adb8d3d..416a1a356dec 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -68,6 +68,10 @@ 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)
@@ -2799,7 +2803,7 @@ static void ilk_write_wm_values(struct drm_i915_private *dev_priv,
 
 	if (dirty & WM_DIRTY_FBC) {
 		val = I915_READ(DISP_ARB_CTL);
-		if (results->enable_fbc_wm)
+		if (!IS_GEN9(dev) && results->enable_fbc_wm)
 			val &= ~DISP_FBC_WM_DIS;
 		else
 			val |= DISP_FBC_WM_DIS;
-- 
2.5.0