drm/i915/execlists: Reorder execlists register enabling

Empirically we restart following a GPU reset 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 requests 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@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170105153023.30575-3-chris@chris-wilson.co.uk

1 files changed, 4 insertions, 14 deletions

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 51ecb395551b..a9eefb171170 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1335,15 +1335,6 @@ out:
         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;
@@ -1353,20 +1344,19 @@ 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 (!execlists_elsp_idle(engine)) {
                 engine->execlist_port[0].count = 0;