[PATCH] drm/i915/sprite: Avoid incurring extra vblank stall when updating plane on IVB

[PATCH] drm/i915/sprite: Avoid incurring extra vblank stall when updating plane on IVB

[Chris Wilson]

IvyBridge requires an extra frame between disabling the low power
watermarks and enabling scaling on the sprite plane. If the scaling
is already enabled, then we have already disabled the low power
watermarks and need not incur an extra wait.

Similarly, as we disable the scaling when turning off the sprite plane,
we can update the scaling enabled flag and restore the low power
watermarks.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
---
 drivers/gpu/drm/i915/intel_sprite.c |   19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index 11545ca..659bcf1 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -110,14 +110,18 @@ ivb_update_plane(struct drm_plane *plane, struct drm_framebuffer *fb,
 	 * when scaling is disabled.
 	 */
 	if (crtc_w != src_w || crtc_h != src_h) {
-		dev_priv->sprite_scaling_enabled = true;
-		intel_update_watermarks(dev);
-		intel_wait_for_vblank(dev, pipe);
+		if (!dev_priv->sprite_scaling_enabled) {
+			dev_priv->sprite_scaling_enabled = true;
+			intel_update_watermarks(dev);
+			intel_wait_for_vblank(dev, pipe);
+		}
 		sprscale = SPRITE_SCALE_ENABLE | (src_w << 16) | src_h;
 	} else {
-		dev_priv->sprite_scaling_enabled = false;
-		/* potentially re-enable LP watermarks */
-		intel_update_watermarks(dev);
+		if (dev_priv->sprite_scaling_enabled) {
+			dev_priv->sprite_scaling_enabled = false;
+			/* potentially re-enable LP watermarks */
+			intel_update_watermarks(dev);
+		}
 	}
 
 	I915_WRITE(SPRSTRIDE(pipe), fb->pitches[0]);
@@ -151,6 +155,9 @@ ivb_disable_plane(struct drm_plane *plane)
 	/* Activate double buffered register update */
 	I915_MODIFY_DISPBASE(SPRSURF(pipe), 0);
 	POSTING_READ(SPRSURF(pipe));
+
+	dev_priv->sprite_scaling_enabled = false;
+	intel_update_watermarks(dev);
 }
 
 static int
-- 
1.7.10

Re: [PATCH] drm/i915/sprite: Avoid incurring extra vblank stall when updating plane on IVB

[Jesse Barnes]

On Wed, 18 Apr 2012 17:12:26 +0100
Chris Wilson <chris@chris-wilson.co.uk> wrote:

> IvyBridge requires an extra frame between disabling the low power
> watermarks and enabling scaling on the sprite plane. If the scaling
> is already enabled, then we have already disabled the low power
> watermarks and need not incur an extra wait.
> 
> Similarly, as we disable the scaling when turning off the sprite plane,
> we can update the scaling enabled flag and restore the low power
> watermarks.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> ---

Yep, this is a good optimization.

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

-- 
Jesse Barnes, Intel Open Source Technology Center

Re: [PATCH] drm/i915/sprite: Avoid incurring extra vblank stall when updating plane on IVB

[Daniel Vetter]

On Wed, Apr 18, 2012 at 09:23:46AM -0700, Jesse Barnes wrote:
> On Wed, 18 Apr 2012 17:12:26 +0100
> Chris Wilson <chris@chris-wilson.co.uk> wrote:
> 
> > IvyBridge requires an extra frame between disabling the low power
> > watermarks and enabling scaling on the sprite plane. If the scaling
> > is already enabled, then we have already disabled the low power
> > watermarks and need not incur an extra wait.
> > 
> > Similarly, as we disable the scaling when turning off the sprite plane,
> > we can update the scaling enabled flag and restore the low power
> > watermarks.
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> > ---
> 
> Yep, this is a good optimization.
> 
> Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Queued for -next, thanks for the patch.
-Daniel
-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48