[Intel-gfx] [PATCH 2/3] drm/i915: Introduce intel_engine_stop_ringbuffer

[Mika Kuoppala]

We use identical sequence of stopping ringbuffer on reset
handing and on ring initialization. Make a function
to handle both cases.

v2: intel_engine_stop_ring, cleaner stop_ring (Chris)

Cc: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_reset.c       | 18 +---------------
 drivers/gpu/drm/i915/intel_engine_cs.c  | 28 +++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_ringbuffer.c | 12 +++--------
 drivers/gpu/drm/i915/intel_ringbuffer.h |  2 ++
 4 files changed, 34 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reset.c b/drivers/gpu/drm/i915/i915_reset.c
index 55d6123dbba4..e7be0bf881c3 100644
--- a/drivers/gpu/drm/i915/i915_reset.c
+++ b/drivers/gpu/drm/i915/i915_reset.c
@@ -113,28 +113,12 @@ void i915_reset_request(struct i915_request *rq, bool guilty)
 
 static void gen3_stop_engine(struct intel_engine_cs *engine)
 {
-	struct drm_i915_private *dev_priv = engine->i915;
-	const u32 base = engine->mmio_base;
-
 	GEM_TRACE("%s\n", engine->name);
 
 	if (intel_engine_stop_cs(engine))
 		GEM_TRACE("%s: timed out on STOP_RING\n", engine->name);
 
-	I915_WRITE_FW(RING_HEAD(base), I915_READ_FW(RING_TAIL(base)));
-	POSTING_READ_FW(RING_HEAD(base)); /* paranoia */
-
-	I915_WRITE_FW(RING_HEAD(base), 0);
-	I915_WRITE_FW(RING_TAIL(base), 0);
-	POSTING_READ_FW(RING_TAIL(base));
-
-	/* The ring must be empty before it is disabled */
-	I915_WRITE_FW(RING_CTL(base), 0);
-
-	/* Check acts as a post */
-	if (I915_READ_FW(RING_HEAD(base)))
-		GEM_TRACE("%s: ring head [%x] not parked\n",
-			  engine->name, I915_READ_FW(RING_HEAD(base)));
+	intel_engine_stop_ring(engine);
 }
 
 static void i915_stop_engines(struct drm_i915_private *i915,
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index e35dc0386bf6..2a94b92cfcd3 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -865,6 +865,34 @@ void intel_engine_cancel_stop_cs(struct intel_engine_cs *engine)
 		      _MASKED_BIT_DISABLE(STOP_RING));
 }
 
+int intel_engine_stop_ring(struct intel_engine_cs *engine)
+{
+	struct drm_i915_private *dev_priv = engine->i915;
+	const u32 base = engine->mmio_base;
+
+	assert_forcewakes_active(dev_priv, FORCEWAKE_ALL);
+	GEM_TRACE("%s\n", engine->name);
+
+	I915_WRITE_FW(RING_HEAD(base), I915_READ_FW(RING_TAIL(base)));
+	POSTING_READ_FW(RING_HEAD(base)); /* paranoia */
+
+	I915_WRITE_FW(RING_HEAD(base), 0);
+	I915_WRITE_FW(RING_TAIL(base), 0);
+	POSTING_READ_FW(RING_TAIL(base));
+
+	/* The ring must be empty before it is disabled */
+	I915_WRITE_FW(RING_CTL(base), 0);
+
+	/* Check acts as a post */
+	if (I915_READ_FW(RING_HEAD(base))) {
+		GEM_TRACE("%s: ring head [%x] not parked\n",
+			  engine->name, I915_READ_FW(RING_HEAD(base)));
+		return -EIO;
+	}
+
+	return 0;
+}
+
 const char *i915_cache_level_str(struct drm_i915_private *i915, int type)
 {
 	switch (type) {
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index d7486f9a29a9..e099ef088d1a 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -615,7 +615,6 @@ static bool ring_is_empty(struct intel_engine_cs *engine)
 
 static bool stop_ring(struct intel_engine_cs *engine)
 {
-	struct drm_i915_private *dev_priv = engine->i915;
 	int ret;
 
 	ret = intel_engine_stop_cs(engine);
@@ -632,15 +631,10 @@ static bool stop_ring(struct intel_engine_cs *engine)
 			return false;
 	}
 
-	I915_WRITE_HEAD(engine, I915_READ_TAIL(engine));
-
-	I915_WRITE_HEAD(engine, 0);
-	I915_WRITE_TAIL(engine, 0);
-
-	/* The ring must be empty before it is disabled */
-	I915_WRITE_CTL(engine, 0);
+	if (intel_engine_stop_ring(engine))
+		return false;
 
-	return (I915_READ_HEAD(engine) & HEAD_ADDR) == 0;
+	return true;
 }
 
 static int init_ring_common(struct intel_engine_cs *engine)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index b8ec7e40a59b..5ed895c56a35 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -843,6 +843,8 @@ int intel_init_vebox_ring_buffer(struct intel_engine_cs *engine);
 int intel_engine_stop_cs(struct intel_engine_cs *engine);
 void intel_engine_cancel_stop_cs(struct intel_engine_cs *engine);
 
+int intel_engine_stop_ring(struct intel_engine_cs *engine);
+
 void intel_engine_set_hwsp_writemask(struct intel_engine_cs *engine, u32 mask);
 
 u64 intel_engine_get_active_head(const struct intel_engine_cs *engine);
-- 
2.17.1