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authorChris Wilson <chris@chris-wilson.co.uk>2011-01-04 18:42:07 +0000
committerChris Wilson <chris@chris-wilson.co.uk>2011-01-11 20:42:53 +0000
commit63256ec5347fb2344a42adbae732b90603c92f35 (patch)
tree5b018e93f38f9e90f3b07beeaac4af08122c5876 /drivers
parent759010728b1323aec03c5baae13fde8f76e44a99 (diff)
drm/i915: Enforce write ordering through the GTT
We need to ensure that writes through the GTT land before any modification to the MMIO registers and so must impose a mandatory write barrier when flushing the GTT domain. This was revealed by relaxing the write ordering by experimentally mapping the registers and the GATT as write-combining. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/gpu/drm/i915/i915_gem.c14
-rw-r--r--drivers/gpu/drm/i915/i915_gem_execbuffer.c3
2 files changed, 16 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index c79c0b62ef60..f9c093c08d58 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2393,6 +2393,12 @@ i915_gem_object_flush_fence(struct drm_i915_gem_object *obj,
obj->last_fenced_ring = NULL;
}
+ /* Ensure that all CPU reads are completed before installing a fence
+ * and all writes before removing the fence.
+ */
+ if (obj->base.read_domains & I915_GEM_DOMAIN_GTT)
+ mb();
+
return 0;
}
@@ -2833,10 +2839,16 @@ i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj)
if (obj->base.write_domain != I915_GEM_DOMAIN_GTT)
return;
- /* No actual flushing is required for the GTT write domain. Writes
+ /* No actual flushing is required for the GTT write domain. Writes
* to it immediately go to main memory as far as we know, so there's
* no chipset flush. It also doesn't land in render cache.
+ *
+ * However, we do have to enforce the order so that all writes through
+ * the GTT land before any writes to the device, such as updates to
+ * the GATT itself.
*/
+ wmb();
+
i915_gem_release_mmap(obj);
old_write_domain = obj->base.write_domain;
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 61129e6759eb..0d42de42868c 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -725,6 +725,9 @@ i915_gem_execbuffer_flush(struct drm_device *dev,
if (flush_domains & I915_GEM_DOMAIN_CPU)
intel_gtt_chipset_flush();
+ if (flush_domains & I915_GEM_DOMAIN_GTT)
+ wmb();
+
if ((flush_domains | invalidate_domains) & I915_GEM_GPU_DOMAINS) {
for (i = 0; i < I915_NUM_RINGS; i++)
if (flush_rings & (1 << i))