[Intel-gfx] [CI 4/6] drm/i915/gt: Disable the ring before resetting HEAD/TAIL

[Mika Kuoppala]

Chris Wilson <chris at chris-wilson.co.uk> writes:

> During the reset of ring submission, we first stop the engine by
> clearing the HEAD/TAIL and marking the ring as disabled. However, it
> would be safer to disable the ring (after emptying) before resetting the
> HEAD/TAIL.
>
> Suggested-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>

Reviewed-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

> ---
>  drivers/gpu/drm/i915/gt/intel_ring_submission.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> index 44159595d909..8a5314b97b04 100644
> --- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> +++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> @@ -301,13 +301,17 @@ static void xcs_sanitize(struct intel_engine_cs *engine)
>  
>  static bool stop_ring(struct intel_engine_cs *engine)
>  {
> +	/* Empty the ring by skipping to the end */
>  	ENGINE_WRITE_FW(engine, RING_HEAD, ENGINE_READ_FW(engine, RING_TAIL));
> -
> -	ENGINE_WRITE_FW(engine, RING_HEAD, 0);
> -	ENGINE_WRITE_FW(engine, RING_TAIL, 0);
> +	ENGINE_POSTING_READ(engine, RING_HEAD);
>  
>  	/* The ring must be empty before it is disabled */
>  	ENGINE_WRITE_FW(engine, RING_CTL, 0);
> +	ENGINE_POSTING_READ(engine, RING_CTL);
> +
> +	/* Then reset the disabled ring */
> +	ENGINE_WRITE_FW(engine, RING_HEAD, 0);
> +	ENGINE_WRITE_FW(engine, RING_TAIL, 0);
>  
>  	return (ENGINE_READ_FW(engine, RING_HEAD) & HEAD_ADDR) == 0;
>  }
> -- 
> 2.20.1
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx