Attachment 57200 Details for Bug 46145 – reinstate the hwstam magic

[patch] reinstate the hwstam magic

hwstam.patch (text/plain), 1.13 KB, created by Daniel Vetter on 2012-02-17 02:10:12 UTC

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Creator: Daniel Vetter

Created: 2012-02-17 02:10:12 UTC

Size: 1.13 KB

patch

obsolete

>commit f8b48b21cb7b587ad918d4ce8dcf28ed7ca0a631
>Author: Daniel Vetter <daniel.vetter@ffwll.ch>
>Date:   Fri Feb 17 11:07:29 2012 +0100
>
>    Revert "drm/i915: enable forcewake voodoo also for gen6"
>    
>    Well, only partially, we keep the forcewake voodoo but reinstate the
>    hwstam crap ...
>    
>    Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>
>diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
>index afd4e03..909b81f 100644
>--- a/drivers/gpu/drm/i915/i915_irq.c
>+++ b/drivers/gpu/drm/i915/i915_irq.c
>@@ -1815,6 +1815,18 @@ static void ironlake_irq_preinstall(struct drm_device *dev)
> 
> 	I915_WRITE(HWSTAM, 0xeffe);
> 
>+	if (IS_GEN6(dev)) {
>+		/* Workaround stalls observed on Sandy Bridge GPUs by
>+		 * making the blitter command streamer generate a
>+		 * write to the Hardware Status Page for
>+		 * MI_USER_INTERRUPT.  This appears to serialize the
>+		 * previous seqno write out before the interrupt
>+		 * happens.
>+		 */
>+		I915_WRITE(GEN6_BLITTER_HWSTAM, ~GEN6_BLITTER_USER_INTERRUPT);
>+		I915_WRITE(GEN6_BSD_HWSTAM, ~GEN6_BSD_USER_INTERRUPT);
>+	}
>+
> 	/* XXX hotplug from PCH */
> 
> 	I915_WRITE(DEIMR, 0xffffffff);

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