Re: [CI 3/5] drm/i915: Disable semaphores on Sandybridge

[Jani Nikula <jani.nikula@linux.intel.com>]

On Tue, 21 Nov 2017, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> Quoting Jani Nikula (2017-11-21 09:57:30)
>> On Mon, 20 Nov 2017, Chris Wilson <chris@chris-wilson.co.uk> wrote:
>> > I should have admitted defeat long ago as there has been a rare but
>> > persistent error on Sandybridge where semaphore signaling did not
>> > propagate to the waiter, leading to a GPU hang.
>> 
>> I'm late to the party, but I think the choice of patch ordering here is
>> a bit unfortunate. Or is it intentional that you can't backport this to
>> stable as-is?
>
> The unmentioned problem with this patch, is that we were using
> semaphores to mask the missed-breadcrumb-syndrome on Sandybridge (and
> that without semaphores we are even more at risk). So I am not too
> concerned in backporting this particular patch further than we are able
> to inspect ourselves.

Should I read between the lines that "the missed-breadcrumb-syndrome"
has been fixed in dinq?

Sounds reasonable. Let's hope this doesn't get picked up by the stable
backport autoselection...

BR,
Jani.


-- 
Jani Nikula, Intel Open Source Technology Center
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