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drm/i915: Protect active fences on i915

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The i915 also uses the fence registers for GPU access to tiled buffers so
we cannot reallocate one whilst it is on the active list. By performing a
LRU scan of the fenced buffers we also avoid waiting the possibility of
waiting on a pinned, or otherwise unusable, buffer.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>
This commit is contained in:
Chris Wilson 2009-02-11 14:26:47 +00:00 • committed by Eric Anholt
parent fc7170ba28
commit d7619c4b9c
1 changed files with 31 additions and 7 deletions
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38
drivers/gpu/drm/i915/i915_gem.c
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@ -1595,18 +1595,32 @@ i915_gem_object_get_fence_reg(struct drm_gem_object *obj, bool write)
/* None available, try to steal one or wait for a user to finish */
if (i == dev_priv->num_fence_regs) {
uint32_t seqno = dev_priv->mm.next_gem_seqno;
loff_t offset;
if (avail == 0)
return -ENOMEM;
/* Could try to use LRU here instead... */
for (i = dev_priv->fence_reg_start;
i < dev_priv->num_fence_regs; i++) {
uint32_t this_seqno;
reg = &dev_priv->fence_regs[i];
old_obj_priv = reg->obj->driver_private;
if (!old_obj_priv->pin_count)
if (old_obj_priv->pin_count)
continue;
/* i915 uses fences for GPU access to tiled buffers */
if (IS_I965G(dev) || !old_obj_priv->active)
break;
/* find the seqno of the first available fence */
this_seqno = old_obj_priv->last_rendering_seqno;
if (this_seqno != 0 &&
reg->obj->write_domain == 0 &&
i915_seqno_passed(seqno, this_seqno))
seqno = this_seqno;
}
/*
@ -1614,15 +1628,25 @@ i915_gem_object_get_fence_reg(struct drm_gem_object *obj, bool write)
* objects to finish before trying again.
*/
if (i == dev_priv->num_fence_regs) {
ret = i915_gem_object_set_to_gtt_domain(reg->obj, 0);
if (ret) {
WARN(ret != -ERESTARTSYS,
"switch to GTT domain failed: %d\n", ret);
return ret;
if (seqno == dev_priv->mm.next_gem_seqno) {
i915_gem_flush(dev,
I915_GEM_GPU_DOMAINS,
I915_GEM_GPU_DOMAINS);
seqno = i915_add_request(dev,
I915_GEM_GPU_DOMAINS);
if (seqno == 0)
return -ENOMEM;
}
ret = i915_wait_request(dev, seqno);
if (ret)
return ret;
goto try_again;
}
BUG_ON(old_obj_priv->active ||
(reg->obj->write_domain & I915_GEM_GPU_DOMAINS));
/*
* Zap this virtual mapping so we can set up a fence again
* for this object next time we need it.