[Intel-gfx] [PATCH 5/7] drm/i915/chv: Skip gen6_gt_check_fifodbg() on CHV

[deepak.s at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

CHV uses the gen8 shadow register mechanism so we shouldn't be
checking the GT FIFO status.

This effectively removes the posting read, so add an explicit
posting read using FORCEWAKE_ACK_VLV (which is what use in
vlv_forcewake_reset()).

Reviewed-by: Mika Kuoppala <mika.kuoppala at intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_uncore.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 5f9200a..d44941b 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -250,9 +250,10 @@ static void __vlv_force_wake_put(struct drm_i915_private *dev_priv,
 		__raw_i915_write32(dev_priv, FORCEWAKE_MEDIA_VLV,
 				_MASKED_BIT_DISABLE(FORCEWAKE_KERNEL));
 
-	/* The below doubles as a POSTING_READ */
-	gen6_gt_check_fifodbg(dev_priv);
-
+	/* something from same cacheline, but !FORCEWAKE_VLV */
+	__raw_posting_read(dev_priv, FORCEWAKE_ACK_VLV);
+	if (!IS_CHERRYVIEW(dev_priv->dev))
+		gen6_gt_check_fifodbg(dev_priv);
 }
 
 static void vlv_force_wake_get(struct drm_i915_private *dev_priv, int fw_engine)
-- 
1.9.1