[Intel-gfx] [PATCH] drm/i915: Actually invalidate the TLB for the SandyBridge HW contexts w/a

[Daniel Vetter]

On Mon, Oct 01, 2012 at 02:27:04PM +0100, Chris Wilson wrote:
> A side-effect of commit 7d54a904285b6e780291b91a518267bec5591913
> Author: Chris Wilson <chris at chris-wilson.co.uk>
> Date:   Fri Aug 10 10:18:10 2012 +0100
> 
>     drm/i915: Apply post-sync write for pipe control invalidates
> 
> was that only a request to emit invalidate flush would result in the
> TLB being invalidated (since it requires synchronisation and so incurs a
> performance penalty). However, the stated w/a for hardware contexts is
> that the TLBs must be invalidated prior to a MI_SET_CONTEXT, yet the w/a
> itself did not request the TLBs to be invalidated...
> 
> Note this w/a does not prevent the hard system hang I experience when
> using hw contexts (with rc6 enabled) on SNB GT1.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Ben Widawsky <ben at bwidawsk.net>

Applied to fixes, thanks for the patch.
-Daniel

> ---
>  drivers/gpu/drm/i915/i915_gem_context.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index b26b592..cd19ecb 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -348,7 +348,7 @@ mi_set_context(struct intel_ring_buffer *ring,
>  	 * itlb_before_ctx_switch.
>  	 */
>  	if (IS_GEN6(ring->dev) && ring->itlb_before_ctx_switch) {
> -		ret = ring->flush(ring, 0, 0);
> +		ret = ring->flush(ring, I915_GEM_GPU_DOMAINS, 0);
>  		if (ret)
>  			return ret;
>  	}
> -- 
> 1.7.10.4
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch