[Intel-gfx] [PATCH v6 3/8] drm/i915/kbl: IPC workaround for kabylake

[Mahesh Kumar]

IPC (Isoch Priority Control) may cause underflows.

KBL WA: When IPC is enabled, watermark latency values must be increased
by 4us across all levels. This brings level 0 up to 6us.

Signed-off-by: Mahesh Kumar <mahesh1.kumar at intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 7090a7c..33d22cc 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3603,6 +3603,10 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
 				fb->modifier == I915_FORMAT_MOD_Yf_TILED;
 	x_tiled = fb->modifier == I915_FORMAT_MOD_X_TILED;
 
+	/* IPC WA for kabylake */
+	if (IS_KABYLAKE(dev_priv) && dev_priv->ipc_enabled)
+		latency += 4;
+
 	if (apply_memory_bw_wa && x_tiled)
 		latency += 15;
 
-- 
2.10.1