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drm/i915: Fallback to single PAGE_SIZE segments for DMA remapping

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If we at first do not succeed with attempting to remap our physical
pages using a coalesced scattergather list, try again with one
scattergather entry per page. This should help with swiotlb as it uses a
limited buffer size and only searches for contiguous chunks within its
buffer aligned up to the next boundary - i.e. we may prematurely cause a
failure as we are unable to utilize the unused space between large
chunks and trigger an error such as:

	 i915 0000:00:02.0: swiotlb buffer is full (sz: 1630208 bytes)

Reported-by: Juergen Gross <jgross@suse.com>
Tested-by: Juergen Gross <jgross@suse.com>
Fixes: 871dfbd67d ("drm/i915: Allow compaction upto SWIOTLB max segment size")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: <drm-intel-fixes@lists.freedesktop.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20161219124346.550-1-chris@chris-wilson.co.uk
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit d766ef5300)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Chris Wilson 2016-12-19 12:43:45 +00:00 committed by Jani Nikula
parent d8953c8326
commit abb0deacb5
1 changed files with 22 additions and 4 deletions
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26
drivers/gpu/drm/i915/i915_gem.c
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@ -2342,7 +2342,8 @@ static struct sg_table *
i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
{
struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
int page_count, i;
const unsigned long page_count = obj->base.size / PAGE_SIZE;
unsigned long i;
struct address_space *mapping;
struct sg_table *st;
struct scatterlist *sg;
@ -2368,7 +2369,7 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
if (st == NULL)
return ERR_PTR(-ENOMEM);
page_count = obj->base.size / PAGE_SIZE;
rebuild_st:
if (sg_alloc_table(st, page_count, GFP_KERNEL)) {
kfree(st);
return ERR_PTR(-ENOMEM);
@ -2427,8 +2428,25 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
i915_sg_trim(st);
ret = i915_gem_gtt_prepare_pages(obj, st);
if (ret)
goto err_pages;
if (ret) {
/* DMA remapping failed? One possible cause is that
* it could not reserve enough large entries, asking
* for PAGE_SIZE chunks instead may be helpful.
*/
if (max_segment > PAGE_SIZE) {
for_each_sgt_page(page, sgt_iter, st)
put_page(page);
sg_free_table(st);
max_segment = PAGE_SIZE;
goto rebuild_st;
} else {
dev_warn(&dev_priv->drm.pdev->dev,
"Failed to DMA remap %lu pages\n",
page_count);
goto err_pages;
}
}
if (i915_gem_object_needs_bit17_swizzle(obj))
i915_gem_object_do_bit_17_swizzle(obj, st);