[Intel-gfx] [PATCH] drm/i915: Manually acquire engine-wakeref around use of kernel_context

[Chris Wilson]

Quoting Chris Wilson (2020-02-24 23:31:10)
> The engine->kernel_context is a special case for request emission. Since
> it is used as the barrier within the engine's wakeref, we must acquire the
> wakeref before submitting a request to the kernel_context.
> 
> Reported-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Lionel Landwerlin <lionel.g.landwerlin at intel.com>

I finally hit the exact symptoms Lionel reported, so no this patch
doesn't fix that, but it is still a potential issue.
-Chris