[Intel-gfx] [PATCH 1/3] drm/i915: Use intel_engine_stop_cs when stopping ringbuffer

[Mika Kuoppala]

We have an exported function for stopping the engine before
disabling a ringbuffer. Take it into use.

v2: use fw on empty check
v3: tail is tail

Cc: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_engine_cs.c  |  3 ++
 drivers/gpu/drm/i915/intel_ringbuffer.c | 41 ++++++++++++++-----------
 2 files changed, 26 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index df8f88142f1d..e35dc0386bf6 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -856,6 +856,9 @@ void intel_engine_cancel_stop_cs(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
 
+	if (INTEL_GEN(dev_priv) < 3)
+		return;
+
 	GEM_TRACE("%s\n", engine->name);
 
 	I915_WRITE_FW(RING_MI_MODE(engine->mmio_base),
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 1b96b0960adc..5fe28d9087b7 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -604,26 +604,32 @@ static void ring_setup_status_page(struct intel_engine_cs *engine)
 	flush_cs_tlb(engine);
 }
 
+static bool ring_is_empty(struct intel_engine_cs *engine)
+{
+	struct drm_i915_private *dev_priv = engine->i915;
+	const u32 base = engine->mmio_base;
+
+	return (I915_READ_FW(RING_HEAD(base)) & HEAD_ADDR) ==
+		(I915_READ_FW(RING_TAIL(base)) & TAIL_ADDR);
+}
+
 static bool stop_ring(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
+	int ret;
 
-	if (INTEL_GEN(dev_priv) > 2) {
-		I915_WRITE_MODE(engine, _MASKED_BIT_ENABLE(STOP_RING));
-		if (intel_wait_for_register(dev_priv,
-					    RING_MI_MODE(engine->mmio_base),
-					    MODE_IDLE,
-					    MODE_IDLE,
-					    1000)) {
-			DRM_ERROR("%s : timed out trying to stop ring\n",
-				  engine->name);
-			/* Sometimes we observe that the idle flag is not
-			 * set even though the ring is empty. So double
-			 * check before giving up.
-			 */
-			if (I915_READ_HEAD(engine) != I915_READ_TAIL(engine))
-				return false;
-		}
+	ret = intel_engine_stop_cs(engine);
+	if (ret == -ENODEV)
+		ret = 0;
+
+	if (ret) {
+		/*
+		 * Sometimes we observe that the idle flag is not
+		 * set even though the ring is empty. So double
+		 * check before giving up.
+		 */
+		if (!ring_is_empty(engine))
+			return false;
 	}
 
 	I915_WRITE_HEAD(engine, I915_READ_TAIL(engine));
@@ -718,8 +724,7 @@ static int init_ring_common(struct intel_engine_cs *engine)
 		goto out;
 	}
 
-	if (INTEL_GEN(dev_priv) > 2)
-		I915_WRITE_MODE(engine, _MASKED_BIT_DISABLE(STOP_RING));
+	intel_engine_cancel_stop_cs(engine);
 
 	/* Now awake, let it get started */
 	if (ring->tail != ring->head) {
-- 
2.17.1