Re: [regression] Re: 4.11-rc0, thinkpad x220: GPU hang

[Pavel Machek <pavel@ucw.cz>]

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On Mon 2017-03-06 11:15:28, Chris Wilson wrote:
> On Mon, Mar 06, 2017 at 12:01:51AM +0100, Pavel Machek wrote:
> > Hi!
> > 
> > > > mplayer stopped working after a while. Dmesg says:
> > > > 
> > > > [ 3000.266533] cdc_ether 2-1.2:1.0 usb0: register 'cdc_ether' at
> > 
> > Now I'm pretty sure it is a regression in v4.11-rc0. Any ideas what to
> > try? Bisect will be slow and nasty :-(.
> 
> I came the conclusion that #99671 is the ring HEAD overtaking the TAIL,
> and under the presumption that your bug matches (as the symptoms do):
> 
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 4ffa35faff49..62e31a7438ac 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -782,10 +782,10 @@ static void i9xx_submit_request(struct drm_i915_gem_request *request)
>  {
>         struct drm_i915_private *dev_priv = request->i915;
>  
> -       i915_gem_request_submit(request);
> -
>         GEM_BUG_ON(!IS_ALIGNED(request->tail, 8));
>         I915_WRITE_TAIL(request->engine, request->tail);
> +
> +       i915_gem_request_submit(request);
>  }
>  
>  static void i9xx_emit_breadcrumb(struct drm_i915_gem_request *req, u32 *cs)

I applied it as:

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 91bc4ab..9c49c7a 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1338,9 +1338,9 @@ static void i9xx_submit_request(struct drm_i915_gem_request *request)
 {
 	struct drm_i915_private *dev_priv = request->i915;
 
-	i915_gem_request_submit(request);
-
 	I915_WRITE_TAIL(request->engine, request->tail);
+
+	i915_gem_request_submit(request);
 }
 
 static void i9xx_emit_breadcrumb(struct drm_i915_gem_request *req,

Hmm. But your next mail suggest that it may not be smart to try to
boot it? :-).

										Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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