On 04/06/2018 08:34, Chris Wilson wrote:
In the unlikely case where we have failed to keep submitting to the GPU,
we end up with the ELSP queue empty but a pending queue of requests.
How does this happen? We have nothing in ports but a queue of requests,
but we managed to declare a GPU hang, even though there is nothing in
ports so GPU looks idle from the outside?
Regards,
Tvrtko
Here, we skip the per-engine reset as there is no guilty request, but in
doing so we also skip the engine restart leaving ourselves with a
permanently hung engine. A quick way to recover is by moving the tasklet
kick to execlists_reset_finish() (from init_hw). We still emit the error
on hanging, so the error is not lost but we should be able to recover.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Cc: Michel Thierry <michel.thierry@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_lrc.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 8d912d0c8fc1..c8d9b5aed94a 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1803,7 +1803,6 @@ static bool unexpected_starting_state(struct intel_engine_cs *engine)
static int gen8_init_common_ring(struct intel_engine_cs *engine)
{
- struct intel_engine_execlists * const execlists = &engine->execlists;
int ret;
ret = intel_mocs_init_engine(engine);
@@ -1821,10 +1820,6 @@ static int gen8_init_common_ring(struct intel_engine_cs *engine)
enable_execlists(engine);
- /* After a GPU reset, we may have requests to replay */
- if (execlists->first)
- tasklet_schedule(&execlists->tasklet);
-
return 0;
}
@@ -2006,6 +2001,12 @@ static void execlists_reset(struct intel_engine_cs *engine,
static void execlists_reset_finish(struct intel_engine_cs *engine)
{
+ struct intel_engine_execlists * const execlists = &engine->execlists;
+
+ /* After a GPU reset, we may have requests to replay */
+ if (execlists->first)
+ tasklet_schedule(&execlists->tasklet);
+
/*
* Flush the tasklet while we still have the forcewake to be sure
* that it is not allowed to sleep before we restart and reload a
@@ -2015,7 +2016,7 @@ static void execlists_reset_finish(struct intel_engine_cs *engine)
* serialising multiple attempts to reset so that we know that we
* are the only one manipulating tasklet state.
*/
- __tasklet_enable_sync_once(&engine->execlists.tasklet);
+ __tasklet_enable_sync_once(&execlists->tasklet);
GEM_TRACE("%s\n", engine->name);
}
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