Re: [PATCH] drm/xe/guc: In guc_ct_send_recv flush g2h worker if g2h resp times out

[Matthew Brost <matthew.brost@intel.com>]

On Sat, Sep 28, 2024 at 12:54:28AM +0530, Badal Nilawar wrote:
> It is observed that for GuC CT request G2H IRQ triggered and g2h_worker
> queued, but it didn't get opportunity to execute and timeout occurred.
> To address this the g2h_worker is being flushed.
> 
> Cc: John Harrison <John.C.Harrison@Intel.com>
> Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_guc_ct.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
> index 4b95f75b1546..4a5d7f85d1a0 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ct.c
> +++ b/drivers/gpu/drm/xe/xe_guc_ct.c
> @@ -903,6 +903,17 @@ static int guc_ct_send_recv(struct xe_guc_ct *ct, const u32 *action, u32 len,
>  	}
>  
>  	ret = wait_event_timeout(ct->g2h_fence_wq, g2h_fence.done, HZ);
> +
> +	/*
> +	 * It is observed that for above GuC CT request G2H IRQ triggered

Where is this observed. 1 second is a long to wait for a worker...

> +	 * and g2h_worker queued, but it didn't get opportunity to execute
> +	 * and timeout occurred. To address the g2h_worker is being flushed.
> +	 */
> +	if (!ret) {
> +		flush_work(&ct->g2h_worker);
> +		ret = wait_event_timeout(ct->g2h_fence_wq, g2h_fence.done, HZ);

If this is needed I wouldn't wait 1 second, if the flush worked
'g2h_fence.done' should immediately be signaled. Maybe wait 1 MS?

Matt

> +	}
> +
>  	if (!ret) {
>  		xe_gt_err(gt, "Timed out wait for G2H, fence %u, action %04x",
>  			  g2h_fence.seqno, action[0]);
> -- 
> 2.34.1
>