Re: [PATCH 5/9] drm/i915/guc: Flush the work queue for GuC generated G2H

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Aug 11, 2021 at 01:16:18AM +0000, Matthew Brost wrote:
> Flush the work queue for GuC generated G2H messages durinr a GT reset.
> This is accomplished by spinning on the the list of outstanding G2H to
> go empty.
> 
> Fixes: eb5e7da736f3 ("drm/i915/guc: Reset implementation for new GuC interface")
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> Cc: <stable@vger.kernel.org>
> ---
>  drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> 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 3cd2da6f5c03..e5eb2df11b4a 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -727,6 +727,11 @@ void intel_guc_submission_reset_prepare(struct intel_guc *guc)
>  			wait_for_reset(guc, &guc->outstanding_submission_g2h);
>  		} while (!list_empty(&guc->ct.requests.incoming));
>  	}
> +
> +	/* Flush any GuC generated G2H */
> +	while (!list_empty(&guc->ct.requests.incoming))
> +		msleep(20);

flush_work or flush_workqueue, beacuse that comes with lockdep
annotations. Dont hand-roll stuff like this if at all possible.
-Daniel

> +
>  	scrub_guc_desc_for_outstanding_g2h(guc);
>  }
>  
> -- 
> 2.32.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch