[Intel-gfx] [PATCH] drm/i915/execlists: Reorder execlists register enabling

[Chris Wilson]

Empirically we restart more successfully if we call lrc_init_hws()
(which contains a posting read) last. (The failure mode that was
observed was that breadcrumb writes into the HWS from the recovered
request went astray leading to the context-switch maintaining forward
progress, but the requests not being retired/completed.)

For clarity, lrc_init_hws() is inlined (and the unused function then
removed).

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Cc: Mika Kuoppala <mika.kuoppala at intel.com>
---
 drivers/gpu/drm/i915/intel_lrc.c | 18 ++++--------------
 1 file changed, 4 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index cc229d5998bb..33fe7e5c9364 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1329,15 +1329,6 @@ static int intel_init_workaround_bb(struct intel_engine_cs *engine)
 	return ret;
 }
 
-static void lrc_init_hws(struct intel_engine_cs *engine)
-{
-	struct drm_i915_private *dev_priv = engine->i915;
-
-	I915_WRITE(RING_HWS_PGA(engine->mmio_base),
-		   engine->status_page.ggtt_offset);
-	POSTING_READ(RING_HWS_PGA(engine->mmio_base));
-}
-
 static int gen8_init_common_ring(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
@@ -1347,20 +1338,19 @@ static int gen8_init_common_ring(struct intel_engine_cs *engine)
 	if (ret)
 		return ret;
 
-	lrc_init_hws(engine);
-
 	intel_engine_reset_breadcrumbs(engine);
+	intel_engine_init_hangcheck(engine);
 
 	I915_WRITE(RING_HWSTAM(engine->mmio_base), 0xffffffff);
-
 	I915_WRITE(RING_MODE_GEN7(engine),
 		   _MASKED_BIT_DISABLE(GFX_REPLAY_MODE) |
 		   _MASKED_BIT_ENABLE(GFX_RUN_LIST_ENABLE));
+	I915_WRITE(RING_HWS_PGA(engine->mmio_base),
+		   engine->status_page.ggtt_offset);
+	POSTING_READ(RING_HWS_PGA(engine->mmio_base));
 
 	DRM_DEBUG_DRIVER("Execlists enabled for %s\n", engine->name);
 
-	intel_engine_init_hangcheck(engine);
-
 	/* After a GPU reset, we may have requests to replay */
 	if (!i915.enable_guc_submission && !execlists_elsp_idle(engine)) {
 		engine->execlist_port[0].count = 0;
-- 
2.11.0