[Intel-gfx] [PATCH 11/28] drm/i915/pm: Move CONTEXT_VALID_BIT check

[Matthew Auld]

On Thu, 21 Oct 2021 at 11:37, Maarten Lankhorst
<maarten.lankhorst at linux.intel.com> wrote:
>
> Resetting will clear the CONTEXT_VALID_BIT, so wait until after that to test.
>

AFAIK this seems to be fixing something earlier in the series(maybe
patch 7?) i.e without this patch we seem to trigger the BUG_ON. If so,
this needs to be much earlier in the series?

Also this probably needs some more commentary in the commit message
for whether moving the BUG_ON matters, or if this is potentially
papering over something significant?

> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Reviewed-by: Niranjana Vishwanathapura <niranjana.vishwanathapura at intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_engine_pm.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> index a1334b48dde7..849fbb229bd3 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> @@ -52,8 +52,6 @@ static int __engine_unpark(struct intel_wakeref *wf)
>         /* Discard stale context state from across idling */
>         ce = engine->kernel_context;
>         if (ce) {
> -               GEM_BUG_ON(test_bit(CONTEXT_VALID_BIT, &ce->flags));
> -
>                 /* Flush all pending HW writes before we touch the context */
>                 while (unlikely(intel_context_inflight(ce)))
>                         intel_engine_flush_submission(engine);
> @@ -68,6 +66,9 @@ static int __engine_unpark(struct intel_wakeref *wf)
>                          ce->timeline->seqno,
>                          READ_ONCE(*ce->timeline->hwsp_seqno),
>                          ce->ring->emit);
> +
> +               GEM_BUG_ON(test_bit(CONTEXT_VALID_BIT, &ce->flags));
> +
>                 GEM_BUG_ON(ce->timeline->seqno !=
>                            READ_ONCE(*ce->timeline->hwsp_seqno));
>         }
> --
> 2.33.0
>