[ 118/171] drm/i915: Add wait_for in init_ring_common

Greg Kroah-Hartman
2013-01-15T23:28:59Z

From: Sean Paul <seanpaul@chromium.org>

commit f01db988ef6f6c70a6cc36ee71e4a98a68901229 upstream.

I have seen a number of "blt ring initialization failed" messages
where the ctl or start registers are not the correct value. Upon further
inspection, if the code just waited a little bit, it would read the
correct value. Adding the wait_for to these reads should eliminate the
issue.

Signed-off-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Julien Cristau <jcristau@debian.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/i915/intel_ringbuffer.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -295,9 +295,9 @@ static int init_ring_common(struct intel
| RING_VALID);

/* If the head is still not zero, the ring is dead */
- if ((I915_READ_CTL(ring) & RING_VALID) == 0 ||
- I915_READ_START(ring) != obj->gtt_offset ||
- (I915_READ_HEAD(ring) & HEAD_ADDR) != 0) {
+ if (wait_for((I915_READ_CTL(ring) & RING_VALID) != 0 &&
+ I915_READ_START(ring) == obj->gtt_offset &&
+ (I915_READ_HEAD(ring) & HEAD_ADDR) == 0, 50)) {
DRM_ERROR("%s initialization failed "
"ctl %08x head %08x tail %08x start %08x\n",
ring->name,