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<b><a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED - [BSW clflush] igt/gem_partial_pwrite_pread subtests fail"
href="https://bugs.freedesktop.org/show_bug.cgi?id=92845#c4">Comment # 4</a>
on <a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED - [BSW clflush] igt/gem_partial_pwrite_pread subtests fail"
href="https://bugs.freedesktop.org/show_bug.cgi?id=92845">bug 92845</a>
from <span class="vcard"><a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> <span class="fn">Chris Wilson</span></a>
</span></b>
<pre>For posterity:
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 3adb163..3187e97 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -517,9 +517,15 @@ shmem_pread_fast(struct page *page, int shmem_page_offset,
int page_length,
return -EINVAL;
vaddr = kmap_atomic(page);
- if (needs_clflush)
- drm_clflush_virt_range(vaddr + shmem_page_offset,
- page_length);
+ if (needs_clflush) {
+ unsigned long start = (unsigned long)vaddr + shmem_page_offset;
+ unsigned long end = start + page_length;
+
+ start = round_down(start, 256);
+ end = round_up(end, 256);
+
+ drm_clflush_virt_range((void *)start, end - start);
+ }</pre>
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