[PATCH 3/3] drm/i915/guc: Flush G2H handler during a GT reset

[John Harrison]

On 1/18/2022 13:43, Matthew Brost wrote:
> Now that the error capture is fully decoupled from fence signalling
> (request retirement to free memory, which is turn depends on resets) we
s/is/in/

With that fixed:
Reviewed-by: John Harrison <John.C.Harrison at Intel.com>

John.

> can safely flush the G2H handler during a GT reset. This is eliminates
> corner cases where GuC generated G2H (e.g. engine resets) race with a GT
> reset.
>
> Signed-off-by: Matthew Brost <mattthew.brost at intel.com>
> ---
>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c  | 18 +-----------------
>   1 file changed, 1 insertion(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index cdd8d691251ff..1a11e8986948b 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -1396,8 +1396,6 @@ static void guc_flush_destroyed_contexts(struct intel_guc *guc);
>   
>   void intel_guc_submission_reset_prepare(struct intel_guc *guc)
>   {
> -	int i;
> -
>   	if (unlikely(!guc_submission_initialized(guc))) {
>   		/* Reset called during driver load? GuC not yet initialised! */
>   		return;
> @@ -1414,21 +1412,7 @@ void intel_guc_submission_reset_prepare(struct intel_guc *guc)
>   
>   	guc_flush_submissions(guc);
>   	guc_flush_destroyed_contexts(guc);
> -
> -	/*
> -	 * Handle any outstanding G2Hs before reset. Call IRQ handler directly
> -	 * each pass as interrupt have been disabled. We always scrub for
> -	 * outstanding G2H as it is possible for outstanding_submission_g2h to
> -	 * be incremented after the context state update.
> -	 */
> -	for (i = 0; i < 4 && atomic_read(&guc->outstanding_submission_g2h); ++i) {
> -		intel_guc_to_host_event_handler(guc);
> -#define wait_for_reset(guc, wait_var) \
> -		intel_guc_wait_for_pending_msg(guc, wait_var, false, (HZ / 20))
> -		do {
> -			wait_for_reset(guc, &guc->outstanding_submission_g2h);
> -		} while (!list_empty(&guc->ct.requests.incoming));
> -	}
> +	flush_work(&guc->ct.requests.worker);
>   
>   	scrub_guc_desc_for_outstanding_g2h(guc);
>   }