Re: [PATCH] drm/xe/guc_submit: Simplify and fix diff calculation

[Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>]

On Tue, May 13, 2025 at 07:25:49AM -0700, Lucas De Marchi wrote:
>With a u32 type, there's no need to check which one is greater: the
>current is always the latest and if it's less than the previous, it's
>because it wrapped: just do the unsigned calculation that will lead to
>the same result, or better the correct one. It fixes an off-by-one in
>the wrapped calculation, however that doesn't really matter for the
>timeout calculation.
>
>Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>

>---
> drivers/gpu/drm/xe/xe_guc_submit.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
>diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
>index fb125f940de8f..80f748baad3f3 100644
>--- a/drivers/gpu/drm/xe/xe_guc_submit.c
>+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
>@@ -976,10 +976,7 @@ static bool check_timeout(struct xe_exec_queue *q, struct xe_sched_job *job)
> 	 */
> 	xe_gt_assert(gt, timeout_ms < 100 * MSEC_PER_SEC);
>
>-	if (ctx_timestamp < ctx_job_timestamp)
>-		diff = ctx_timestamp + U32_MAX - ctx_job_timestamp;
>-	else
>-		diff = ctx_timestamp - ctx_job_timestamp;
>+	diff = ctx_timestamp - ctx_job_timestamp;
>
> 	/*
> 	 * Ensure timeout is within 5% to account for an GuC scheduling latency
>
>
>