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-rw-r--r--drivers/gpu/drm/i915/i915_gem.c37
1 files changed, 35 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index a31ee3202f17..94b9bdce0c75 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2350,6 +2350,7 @@ i915_gem_init_ringbuffer(struct drm_device *dev)
struct drm_gem_object *obj;
struct drm_i915_gem_object *obj_priv;
int ret;
+ u32 head;
ret = i915_gem_init_hws(dev);
if (ret != 0)
@@ -2390,17 +2391,49 @@ i915_gem_init_ringbuffer(struct drm_device *dev)
/* Stop the ring if it's running. */
I915_WRITE(PRB0_CTL, 0);
- I915_WRITE(PRB0_HEAD, 0);
I915_WRITE(PRB0_TAIL, 0);
- I915_WRITE(PRB0_START, 0);
+ I915_WRITE(PRB0_HEAD, 0);
/* Initialize the ring. */
I915_WRITE(PRB0_START, obj_priv->gtt_offset);
+ head = I915_READ(PRB0_HEAD) & HEAD_ADDR;
+
+ /* G45 ring initialization fails to reset head to zero */
+ if (head != 0) {
+ DRM_ERROR("Ring head not reset to zero "
+ "ctl %08x head %08x tail %08x start %08x\n",
+ I915_READ(PRB0_CTL),
+ I915_READ(PRB0_HEAD),
+ I915_READ(PRB0_TAIL),
+ I915_READ(PRB0_START));
+ I915_WRITE(PRB0_HEAD, 0);
+
+ DRM_ERROR("Ring head forced to zero "
+ "ctl %08x head %08x tail %08x start %08x\n",
+ I915_READ(PRB0_CTL),
+ I915_READ(PRB0_HEAD),
+ I915_READ(PRB0_TAIL),
+ I915_READ(PRB0_START));
+ }
+
I915_WRITE(PRB0_CTL,
((obj->size - 4096) & RING_NR_PAGES) |
RING_NO_REPORT |
RING_VALID);
+ head = I915_READ(PRB0_HEAD) & HEAD_ADDR;
+
+ /* If the head is still not zero, the ring is dead */
+ if (head != 0) {
+ DRM_ERROR("Ring initialization failed "
+ "ctl %08x head %08x tail %08x start %08x\n",
+ I915_READ(PRB0_CTL),
+ I915_READ(PRB0_HEAD),
+ I915_READ(PRB0_TAIL),
+ I915_READ(PRB0_START));
+ return -EIO;
+ }
+
/* Update our cache of the ring state */
i915_kernel_lost_context(dev);