powerpc/pseries: Improve stream generation comments in copypage/user
No code changes, just documenting what's happening a little better.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/lib/copypage_power7.S b/arch/powerpc/lib/copypage_power7.S
index 0ef75bf..395c594 100644
--- a/arch/powerpc/lib/copypage_power7.S
+++ b/arch/powerpc/lib/copypage_power7.S
@@ -28,13 +28,14 @@
* aligned we don't need to clear the bottom 7 bits of either
* address.
*/
- ori r9,r3,1 /* stream=1 */
+ ori r9,r3,1 /* stream=1 => to */
#ifdef CONFIG_PPC_64K_PAGES
- lis r7,0x0E01 /* depth=7, units=512 */
+ lis r7,0x0E01 /* depth=7
+ * units/cachelines=512 */
#else
lis r7,0x0E00 /* depth=7 */
- ori r7,r7,0x1000 /* units=32 */
+ ori r7,r7,0x1000 /* units/cachelines=32 */
#endif
ori r10,r7,1 /* stream=1 */
@@ -43,12 +44,14 @@
.machine push
.machine "power4"
- dcbt r0,r4,0b01000
- dcbt r0,r7,0b01010
- dcbtst r0,r9,0b01000
- dcbtst r0,r10,0b01010
+ /* setup read stream 0 */
+ dcbt r0,r4,0b01000 /* addr from */
+ dcbt r0,r7,0b01010 /* length and depth from */
+ /* setup write stream 1 */
+ dcbtst r0,r9,0b01000 /* addr to */
+ dcbtst r0,r10,0b01010 /* length and depth to */
eieio
- dcbt r0,r8,0b01010 /* GO */
+ dcbt r0,r8,0b01010 /* all streams GO */
.machine pop
#ifdef CONFIG_ALTIVEC