[PATCH] drm/xe/guc: skip TDR timeout check when ctx_timestamp is 0 or 1

[Jia Yao <jia.yao@intel.com>]

A ctx_timestamp of 0 or 1 indicates an invalid timestamp:
- 1 (CONTEXT_ACTIVE) is the cookie written by the WA BB immediately
  after a full context restore, before the spinner has run.
- 0 can occur when lrc->ctx_timestamp shadow is uninitialized or was
  last updated while the context was being restored.

In both cases the timestamp is not yet valid, so reset the sampling
baseline and wait for the next check_timeout() call.

Signed-off-by: Jia Yao <jia.yao@intel.com>
---
 drivers/gpu/drm/xe/xe_guc_submit.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index 0a6e2b81b5a5..caf02d265533 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -1429,6 +1429,20 @@ static bool check_timeout(struct xe_exec_queue *q, struct xe_sched_job *job)
 		return xe_sched_invalidate_job(job, 0);
 	}
 
+	/*
+	 * A ctx_timestamp of 0 or 1 indicates an invalid timestamp:
+	 * - 1 (CONTEXT_ACTIVE) is the cookie written by the WA BB immediately
+	 *   after a full context restore, before the spinner has run.
+	 * - 0 can occur when lrc->ctx_timestamp shadow is uninitialized or was
+	 *   last updated while the context was being restored.
+	 * In both cases the timestamp is not yet valid, so reset the sampling
+	 * baseline and wait for the next check_timeout() call.
+	 */
+	if (ctx_timestamp <= 1) {
+		job->sample_timestamp = U64_MAX;
+		return false;
+	}
+
 	job->sample_timestamp = ctx_timestamp;
 	ctx_job_timestamp = xe_lrc_ctx_job_timestamp(q->lrc[0]);
 
-- 
2.43.0