1 files changed, 34 insertions, 20 deletions

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 6bc68bdcf43..79fb4cc2137 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -437,32 +437,41 @@ static void ring_setup_phys_status_page(struct intel_ring_buffer *ring)
 	I915_WRITE(HWS_PGA, addr);
 }
 
-static int init_ring_common(struct intel_ring_buffer *ring)
+static bool stop_ring(struct intel_ring_buffer *ring)
 {
-	struct drm_device *dev = ring->dev;
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct drm_i915_gem_object *obj = ring->obj;
-	int ret = 0;
-	u32 head;
+	struct drm_i915_private *dev_priv = to_i915(ring->dev);
 
-	gen6_gt_force_wake_get(dev_priv, FORCEWAKE_ALL);
+	if (!IS_GEN2(ring->dev)) {
+		I915_WRITE_MODE(ring, _MASKED_BIT_ENABLE(STOP_RING));
+		if (wait_for_atomic((I915_READ_MODE(ring) & MODE_IDLE) != 0, 1000)) {
+			DRM_ERROR("%s :timed out trying to stop ring\n", ring->name);
+			return false;
+		}
+	}
 
-	/* Stop the ring if it's running. */
 	I915_WRITE_CTL(ring, 0);
 	I915_WRITE_HEAD(ring, 0);
 	ring->write_tail(ring, 0);
-	if (wait_for_atomic((I915_READ_MODE(ring) & MODE_IDLE) != 0, 1000))
-		DRM_ERROR("%s :timed out trying to stop ring\n", ring->name);
 
-	if (I915_NEED_GFX_HWS(dev))
-		intel_ring_setup_status_page(ring);
-	else
-		ring_setup_phys_status_page(ring);
+	if (!IS_GEN2(ring->dev)) {
+		(void)I915_READ_CTL(ring);
+		I915_WRITE_MODE(ring, _MASKED_BIT_DISABLE(STOP_RING));
+	}
 
-	head = I915_READ_HEAD(ring) & HEAD_ADDR;
+	return (I915_READ_HEAD(ring) & HEAD_ADDR) == 0;
+}
 
-	/* G45 ring initialization fails to reset head to zero */
-	if (head != 0) {
+static int init_ring_common(struct intel_ring_buffer *ring)
+{
+	struct drm_device *dev = ring->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_i915_gem_object *obj = ring->obj;
+	int ret = 0;
+
+	gen6_gt_force_wake_get(dev_priv, FORCEWAKE_ALL);
+
+	if (!stop_ring(ring)) {
+		/* G45 ring initialization often fails to reset head to zero */
 		DRM_DEBUG_KMS("%s head not reset to zero "
 			      "ctl %08x head %08x tail %08x start %08x\n",
 			      ring->name,
@@ -471,9 +480,7 @@ static int init_ring_common(struct intel_ring_buffer *ring)
 			      I915_READ_TAIL(ring),
 			      I915_READ_START(ring));
 
-		I915_WRITE_HEAD(ring, 0);
-
-		if (I915_READ_HEAD(ring) & HEAD_ADDR) {
+		if (!stop_ring(ring)) {
 			DRM_ERROR("failed to set %s head to zero "
 				  "ctl %08x head %08x tail %08x start %08x\n",
 				  ring->name,
@@ -481,9 +488,16 @@ static int init_ring_common(struct intel_ring_buffer *ring)
 				  I915_READ_HEAD(ring),
 				  I915_READ_TAIL(ring),
 				  I915_READ_START(ring));
+			ret = -EIO;
+			goto out;
 		}
 	}
 
+	if (I915_NEED_GFX_HWS(dev))
+		intel_ring_setup_status_page(ring);
+	else
+		ring_setup_phys_status_page(ring);
+
 	/* Initialize the ring. This must happen _after_ we've cleared the ring
 	 * registers with the above sequence (the readback of the HEAD registers
 	 * also enforces ordering), otherwise the hw might lose the new ring