From: Chris Wilson <chris@chris-wilson.co.uk>
To: intel-gfx@lists.freedesktop.org
Subject: [PATCH] drm/i915: Perform a posting read of the ring start before enabling
Date: Wed, 5 Dec 2012 13:07:50 +0000 [thread overview]
Message-ID: <1354712870-14640-1-git-send-email-chris@chris-wilson.co.uk> (raw)
Mostly paranoia as the writes to the ring registers should not be
reordered, but it should function well as an addition explicit check in
a mysteriously fragile bit of code.
References: https://bugs.freedesktop.org/show_bug.cgi?id=54575
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/intel_ringbuffer.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 53edce0..d5d5177 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -393,6 +393,9 @@ static int init_ring_common(struct intel_ring_buffer *ring)
* also enforces ordering), otherwise the hw might lose the new ring
* register values. */
I915_WRITE_START(ring, obj->gtt_offset);
+ if (I915_READ_START(ring) != obj->gtt_offset)
+ DRM_ERROR("failed to set %s start to GTT offset\n", ring->name);
+
I915_WRITE_CTL(ring,
((ring->size - PAGE_SIZE) & RING_NR_PAGES)
| RING_VALID);
--
1.7.10.4
reply other threads:[~2012-12-05 13:09 UTC|newest]
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