Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
> When doing a GPU reset, the CSB register will be trashed and we will
> lose any context-switch notifications that happened since the tasklet
> was disabled. If we find that all requests on this engine were
> completed, we want to make sure that the ELSP tracker is similarly empty
> so that we do not feed back in the completed requests upon recovering
> from the reset.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_lrc.c | 36 ++++++++++++++++++++++++++----------
> 1 file changed, 26 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 3c83f2dd6798..ad61d1998fb7 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -1327,6 +1327,31 @@ static void reset_common_ring(struct intel_engine_cs *engine,
> {
> struct execlist_port *port = engine->execlist_port;
> struct intel_context *ce;
> + unsigned int n;
> +
> + /*
> + * Catch up with any missed context-switch interrupts.
> + *
> + * Ideally we would just read the remaining CSB entries now that we
> + * know the gpu is idle. However, the CSB registers are sometimes^W
> + * often trashed across a GPU reset! Instead we have to rely on
> + * guessing the missed context-switch events by looking at what
> + * requests were completed.
> + */
> + if (!request) {
> + for (n = 0; n < ARRAY_SIZE(engine->execlist_port); n++)
You need to check against null before put in here?
-Mika
> + i915_gem_request_put(port_request(&port[n]));
> + memset(engine->execlist_port, 0, sizeof(engine->execlist_port));
> + return;
> + }
> +
> + if (request->ctx != port_request(port)->ctx) {
> + i915_gem_request_put(port_request(port));
> + port[0] = port[1];
> + memset(&port[1], 0, sizeof(port[1]));
> + }
> +
> + GEM_BUG_ON(request->ctx != port_request(port)->ctx);
>
> /* If the request was innocent, we leave the request in the ELSP
> * and will try to replay it on restarting. The context image may
> @@ -1338,7 +1363,7 @@ static void reset_common_ring(struct intel_engine_cs *engine,
> * and have to at least restore the RING register in the context
> * image back to the expected values to skip over the guilty request.
> */
> - if (!request || request->fence.error != -EIO)
> + if (request->fence.error != -EIO)
> return;
>
> /* We want a simple context + ring to execute the breadcrumb update.
> @@ -1360,15 +1385,6 @@ static void reset_common_ring(struct intel_engine_cs *engine,
> request->ring->head = request->postfix;
> intel_ring_update_space(request->ring);
>
> - /* Catch up with any missed context-switch interrupts */
> - if (request->ctx != port_request(port)->ctx) {
> - i915_gem_request_put(port_request(port));
> - port[0] = port[1];
> - memset(&port[1], 0, sizeof(port[1]));
> - }
> -
> - GEM_BUG_ON(request->ctx != port_request(port)->ctx);
> -
> /* Reset WaIdleLiteRestore:bdw,skl as well */
> request->tail =
> intel_ring_wrap(request->ring,
> --
> 2.13.2
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