diff mbox

[0908/1094] x86: Use clflushopt in drm_clflush_page

Message ID 1413889294-31328-909-git-send-email-dheerajx.s.jamwal@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Dheeraj Jamwal Oct. 21, 2014, 10:58 a.m. UTC 
From: Ross Zwisler <ross.zwisler@linux.intel.com>

If clflushopt is available on the system, use it instead of clflush in
drm_clflush_page.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Link: http://lkml.kernel.org/r/1393441612-19729-4-git-send-email-ross.zwisler@linux.intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
(cherry picked from commit 2a0c772f1967565d5b71a98012e74d5a7bddc1c4)

Signed-off-by: Dheeraj Jamwal <dheerajx.s.jamwal@intel.com>
---
 drivers/gpu/drm/drm_cache.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
diff mbox

Patch

diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c
index 4bfad5f..6b6dcb1 100644
--- a/drivers/gpu/drm/drm_cache.c
+++ b/drivers/gpu/drm/drm_cache.c
@@ -32,6 +32,12 @@ 
 #include <drm/drmP.h>
 
 #if defined(CONFIG_X86)
+
+/*
+ * clflushopt is an unordered instruction which needs fencing with mfence or
+ * sfence to avoid ordering issues.  For drm_clflush_page this fencing happens
+ * in the caller.
+ */
 static void
 drm_clflush_page(struct page *page)
 {
@@ -44,7 +50,7 @@  drm_clflush_page(struct page *page)
 
 	page_virtual = kmap_atomic(page);
 	for (i = 0; i < PAGE_SIZE; i += size)
-		clflush(page_virtual + i);
+		clflushopt(page_virtual + i);
 	kunmap_atomic(page_virtual);
 }