[PATCH v2 07/15] drm/i915: Drop useless posting reads from cursor commit

[ville.syrjala@xxxxxxxxxxxxxxx]

From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>

There should be no need to do posting reads between all the cursor
register accessess. Let's just drop them.

v2: Rebase due to I915_WRITE_FW() and uncore.lock

Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> #v1
---
 drivers/gpu/drm/i915/intel_display.c | 32 +++++++++++++++-----------------
 1 file changed, 15 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index bc0e71fda90c..bba763b03d28 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9223,30 +9223,28 @@ static void i845_update_cursor(struct intel_plane *plane,
 		 * whilst the cursor is disabled.
 		 */
 		I915_WRITE_FW(CURCNTR(PIPE_A), 0);
-		POSTING_READ_FW(CURCNTR(PIPE_A));
 		plane->cursor.cntl = 0;
 	}
 
-	if (plane->cursor.base != base) {
+	if (plane->cursor.base != base)
 		I915_WRITE_FW(CURBASE(PIPE_A), base);
-		plane->cursor.base = base;
-	}
 
-	if (plane->cursor.size != size) {
+	if (plane->cursor.size != size)
 		I915_WRITE_FW(CURSIZE, size);
-		plane->cursor.size = size;
-	}
 
 	if (cntl)
 		I915_WRITE_FW(CURPOS(PIPE_A), pos);
 
-	if (plane->cursor.cntl != cntl) {
+	if (plane->cursor.cntl != cntl)
 		I915_WRITE_FW(CURCNTR(PIPE_A), cntl);
-		POSTING_READ_FW(CURCNTR(PIPE_A));
-		plane->cursor.cntl = cntl;
-	}
+
+	POSTING_READ_FW(CURCNTR(PIPE_A));
 
 	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
+
+	plane->cursor.cntl = cntl;
+	plane->cursor.base = base;
+	plane->cursor.size = size;
 }
 
 static void i845_disable_cursor(struct intel_plane *plane,
@@ -9309,21 +9307,21 @@ static void i9xx_update_cursor(struct intel_plane *plane,
 
 	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
 
-	if (plane->cursor.cntl != cntl) {
+	if (plane->cursor.cntl != cntl)
 		I915_WRITE_FW(CURCNTR(pipe), cntl);
-		POSTING_READ_FW(CURCNTR(pipe));
-		plane->cursor.cntl = cntl;
-	}
 
 	if (cntl)
 		I915_WRITE_FW(CURPOS(pipe), pos);
 
-	/* and commit changes on next vblank */
-	I915_WRITE_FW(CURBASE(pipe), base);
+	if (plane->cursor.cntl != cntl ||
+	    plane->cursor.base != base)
+		I915_WRITE_FW(CURBASE(pipe), base);
+
 	POSTING_READ_FW(CURBASE(pipe));
 
 	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
 
+	plane->cursor.cntl = cntl;
 	plane->cursor.base = base;
 }
 
-- 
2.10.2

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