[PATCH v2 1/1] drm/i915/gt: Increase a time to retry RING_HEAD reset

[Andi Shyti]

Hi Nitin,

On Fri, Dec 06, 2024 at 03:15:43PM +0530, Nitin Gote wrote:
> Issue seen again where engine resets fails because the engine resumes from
> an incorrect RING_HEAD. HEAD is still not 0 even after writing into it.
> This seems to be timing issue and we experimented different values from 5ms
> to 50ms and found out that 50ms works best based on testing.
> So, if write doesn't succeed at first then retry again.
> 
> Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/12806
> Signed-off-by: Nitin Gote <nitin.r.gote at intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_ring_submission.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> index 32f3b52a183a..bc9f28524713 100644
> --- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> +++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> @@ -231,7 +231,7 @@ static int xcs_resume(struct intel_engine_cs *engine)
>  	set_pp_dir(engine);
>  
>  	/* First wake the ring up to an empty/idle ring */
> -	for ((kt) = ktime_get() + (2 * NSEC_PER_MSEC);
> +	for ((kt) = ktime_get() + (50 * NSEC_PER_MSEC);

Can we please add the comment here as I suggested in v1? If you
don't see it necessary, please feel free to comment it here.

Thanks,
Andi