drm/i915/execlists: Move clearing submission count from reset to init

After a GPU reset, we want to replay our queue of requests. However, the
GPU reset clobbered the state and we only fixup the state for the guilty
request - and engines deemed innocent we try to leave untouched so that
we recover as completely as possible. However, we need to clear the sw
tracking of the ELSP ports even for innocent requests, so move the clear
to the common path of init_hw (from reset_hw).

Reported-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161004201132.21801-3-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_lrc.c

@@ -1242,8 +1242,12 @@ static int gen8_init_common_ring(struct intel_engine_cs *engine)
 
 	intel_engine_init_hangcheck(engine);
 
-	if (!execlists_elsp_idle(engine))
+	/* After a GPU reset, we may have requests to replay */
+	if (!execlists_elsp_idle(engine)) {
+		engine->execlist_port[0].count = 0;
+		engine->execlist_port[1].count = 0;
 		execlists_submit_ports(engine);
+	}
 
 	return 0;
 }
@@ -1318,10 +1322,7 @@ static void reset_common_ring(struct intel_engine_cs *engine,
 		memset(&port[1], 0, sizeof(port[1]));
 	}
 
-	/* CS is stopped, and we will resubmit both ports on resume */
 	GEM_BUG_ON(request->ctx != port[0].request->ctx);
-	port[0].count = 0;
-	port[1].count = 0;
 
 	/* Reset WaIdleLiteRestore:bdw,skl as well */
 	request->tail = request->wa_tail - WA_TAIL_DWORDS * sizeof(u32);