Re: [PATCH] drm/i915: Reset request handling for gen8+

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> On Thu, Jun 18, 2015 at 12:51:40PM +0300, Mika Kuoppala wrote:
>> In order for gen8+ hardware to guarantee that no context switch
>> takes place during engine reset and that current context is properly
>> saved, the driver needs to notify and query hw before commencing
>> with reset.
>> 
>> There are gpu hangs where the engine gets so stuck that it never will
>> report to be ready for reset. We could proceed with reset anyway, but
>> with some hangs with skl, the forced gpu reset will result in a system
>> hang. By inspecting the unreadiness for reset seems to correlate with
>> the probable system hang.
>> 
>> We will only proceed with reset if all engines report that they
>> are ready for reset. If root cause for system hang is found and
>> can be worked around with another means, we can reconsider if
>> we can reinstate full reset for unreadiness case.
>> 
>> v2: -EIO, Recovery, gen8 (Chris, Tomas, Daniel)
>> v3: updated commit msg
>> v4: timeout_ms, simpler error path (Chris)
>> 
>> References: https://bugs.freedesktop.org/show_bug.cgi?id=89959
>> References: https://bugs.freedesktop.org/show_bug.cgi?id=90854
>> Testcase: igt/gem_concurrent_blit --r prw-blt-overwrite-source-read-rcs-forked
>> Testcase: igt/gem_concurrent_blit --r gtt-blt-overwrite-source-read-rcs-forked
>
> Is this the new format for subtests?

No. It is me cutpasting from scripts. Daniel could you please
fix while merging.

Thanks,
-Mika

> I thought the form was
> igt/gem_concurrent_blit/prw-blt-overwrite-source-read-rcs-forked
>
>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>> Cc: Tomas Elf <tomas.elf@intel.com>
>> Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
>
> Lgtm,
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
> -Chris
>
> -- 
> Chris Wilson, Intel Open Source Technology Centre
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