[Intel-gfx] [PATCH] drm/i915: Print error state times relative to capture

[Mika Kuoppala]

Using plain jiffies in error state output makes the output
time differences relative to the current system time. This
is wrong as it makes output time differences dependent
of when the error state is printed rather than when it is
captured.

Store capture jiffies into error state and use it
when outputting the state to fix time differences output.

Cc: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_gpu_error.c | 20 +++++++++++++-------
 drivers/gpu/drm/i915/i915_gpu_error.h |  1 +
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index effaf982b19b..fc7e76f21111 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -404,7 +404,8 @@ static const char *bannable(const struct drm_i915_error_context *ctx)
 
 static void error_print_request(struct drm_i915_error_state_buf *m,
 				const char *prefix,
-				const struct drm_i915_error_request *erq)
+				const struct drm_i915_error_request *erq,
+				const unsigned long timestamp)
 {
 	if (!erq->seqno)
 		return;
@@ -412,7 +413,7 @@ static void error_print_request(struct drm_i915_error_state_buf *m,
 	err_printf(m, "%s pid %d, ban score %d, seqno %8x:%08x, prio %d, emitted %dms ago, head %08x, tail %08x\n",
 		   prefix, erq->pid, erq->ban_score,
 		   erq->context, erq->seqno, erq->priority,
-		   jiffies_to_msecs(jiffies - erq->jiffies),
+		   jiffies_to_msecs(timestamp - erq->jiffies),
 		   erq->head, erq->tail);
 }
 
@@ -427,7 +428,8 @@ static void error_print_context(struct drm_i915_error_state_buf *m,
 }
 
 static void error_print_engine(struct drm_i915_error_state_buf *m,
-			       const struct drm_i915_error_engine *ee)
+			       const struct drm_i915_error_engine *ee,
+			       const unsigned long timestamp)
 {
 	int n;
 
@@ -499,12 +501,12 @@ static void error_print_engine(struct drm_i915_error_state_buf *m,
 		   hangcheck_action_to_str(ee->hangcheck_action));
 	err_printf(m, "  hangcheck action timestamp: %lu, %u ms ago\n",
 		   ee->hangcheck_timestamp,
-		   jiffies_to_msecs(jiffies - ee->hangcheck_timestamp));
+		   jiffies_to_msecs(timestamp - ee->hangcheck_timestamp));
 	err_printf(m, "  engine reset count: %u\n", ee->reset_count);
 
 	for (n = 0; n < ee->num_ports; n++) {
 		err_printf(m, "  ELSP[%d]:", n);
-		error_print_request(m, " ", &ee->execlist[n]);
+		error_print_request(m, " ", &ee->execlist[n], timestamp);
 	}
 
 	error_print_context(m, "  Active context: ", &ee->context);
@@ -650,6 +652,7 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
 	ts = ktime_to_timespec64(error->uptime);
 	err_printf(m, "Uptime: %lld s %ld us\n",
 		   (s64)ts.tv_sec, ts.tv_nsec / NSEC_PER_USEC);
+	err_printf(m, "Jiffies: %lu (now %lu)\n", error->timestamp, jiffies);
 
 	for (i = 0; i < ARRAY_SIZE(error->engine); i++) {
 		if (error->engine[i].hangcheck_stalled &&
@@ -710,7 +713,8 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
 
 	for (i = 0; i < ARRAY_SIZE(error->engine); i++) {
 		if (error->engine[i].engine_id != -1)
-			error_print_engine(m, &error->engine[i]);
+			error_print_engine(m, &error->engine[i],
+					   error->timestamp);
 	}
 
 	for (i = 0; i < ARRAY_SIZE(error->active_vm); i++) {
@@ -769,7 +773,8 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
 				   dev_priv->engine[i]->name,
 				   ee->num_requests);
 			for (j = 0; j < ee->num_requests; j++)
-				error_print_request(m, " ", &ee->requests[j]);
+				error_print_request(m, " ", &ee->requests[j],
+						    error->timestamp);
 		}
 
 		if (IS_ERR(ee->waiters)) {
@@ -1743,6 +1748,7 @@ static int capture(void *data)
 	error->boottime = ktime_get_boottime();
 	error->uptime = ktime_sub(ktime_get(),
 				  error->i915->gt.last_init_time);
+	error->timestamp = jiffies;
 
 	capture_params(error);
 	capture_gen_state(error);
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.h b/drivers/gpu/drm/i915/i915_gpu_error.h
index c05b6034d718..1f36ad526bc5 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.h
+++ b/drivers/gpu/drm/i915/i915_gpu_error.h
@@ -30,6 +30,7 @@ struct i915_gpu_state {
 	ktime_t time;
 	ktime_t boottime;
 	ktime_t uptime;
+	unsigned long timestamp; /* jiffies */
 
 	struct drm_i915_private *i915;
 
-- 
2.14.1