powerpc/pseries: Improve stream generation comments in copypage/user
Michael Neuling [Wed, 29 May 2013 19:34:29 +0000 (19:34 +0000)]
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>

arch/powerpc/lib/copypage_power7.S
arch/powerpc/lib/copyuser_power7.S

index 0ef75bf..395c594 100644 (file)
@@ -28,13 +28,14 @@ _GLOBAL(copypage_power7)
         * 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 @@ _GLOBAL(copypage_power7)
 
 .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
index 0d24ff1..d1f1179 100644 (file)
@@ -318,12 +318,14 @@ err1;     stb     r0,0(r3)
 
 .machine push
 .machine "power4"
-       dcbt    r0,r6,0b01000
-       dcbt    r0,r7,0b01010
-       dcbtst  r0,r9,0b01000
-       dcbtst  r0,r10,0b01010
+       /* setup read stream 0 */
+       dcbt    r0,r6,0b01000   /* 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
 
        beq     cr1,.Lunwind_stack_nonvmx_copy