[Intel-gfx] [PATCH] drm/i915/selftests: Try to recover from a wedged GPU during reset tests

[Chris Wilson]

Quoting Chris Wilson (2017-09-15 14:09:29)
> If we see the seqno stop progressing, we abandon the test for fear that
> the GPU died following the reset. However, during test teardown we still
> wait for the GPU to idle before continuing, but we have already
> confirmed that the GPU is dead. Furthermore, since we are inside a reset
> test, we have disabled the hangchecker, and so there is no safety net and
> we wait indefinitely. Detect the stuck GPU and declare it wedged as a
> state of emergency so we can escape.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Jari Tahvanainen <jari.tahvanainen at intel.com>
> Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/selftests/intel_hangcheck.c | 25 +++++++++++++++++++-----
>  1 file changed, 20 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/selftests/intel_hangcheck.c b/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
> index 02e52a146ed8..913fe752f6b4 100644
> --- a/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
> +++ b/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
> @@ -165,6 +165,7 @@ static int emit_recurse_batch(struct hang *h,
>                 *batch++ = lower_32_bits(vma->node.start);
>         }
>         *batch++ = MI_BATCH_BUFFER_END; /* not reached */
> +       wmb();
>  
>         flags = 0;
>         if (INTEL_GEN(vm->i915) <= 5)
> @@ -621,7 +622,12 @@ static int igt_wait_reset(void *arg)
>         __i915_add_request(rq, true);
>  
>         if (!wait_for_hang(&h, rq)) {
> -               pr_err("Failed to start request %x\n", rq->fence.seqno);
> +               pr_err("Failed to start request %x, at %x\n",
> +                      rq->fence.seqno, hws_seqno(&h, rq));
> +
> +               i915_reset(i915, 0);
> +               i915_gem_set_wedged(i915);
> +
>                 err = -EIO;
>                 goto out_rq;
>         }
> @@ -708,10 +714,14 @@ static int igt_reset_queue(void *arg)
>                         __i915_add_request(rq, true);
>  
>                         if (!wait_for_hang(&h, prev)) {
> -                               pr_err("Failed to start request %x\n",
> -                                      prev->fence.seqno);
> +                               pr_err("Failed to start request %x, at %x\n",
> +                                      rq->fence.seqno, hws_seqno(&h, rq));

Odd one out needs s/rq/prev/
-Chris