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Subject[PATCH] [28/139] ARM: 6535/1: V6 MPCore v6_dma_inv_range and v6_dma_flush_range RWFO fix
Date
2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Valentine Barshak <vbarshak@mvista.com>

commit 85b093bcc5322baa811a03ec73de0909c157f181 upstream.

Cache ownership must be acquired by reading/writing data from the
cache line to make cache operation have the desired effect on the
SMP MPCore CPU. However, the ownership is never acquired in the
v6_dma_inv_range function when cleaning the first line and
flushing the last one, in case the address is not aligned
to D_CACHE_LINE_SIZE boundary.
Fix this by reading/writing data if needed, before performing
cache operations.
While at it, fix v6_dma_flush_range to prevent RWFO outside
the buffer.

Signed-off-by: Valentine Barshak <vbarshak@mvista.com>
Signed-off-by: George G. Davis <gdavis@mvista.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

---
arch/arm/mm/cache-v6.S | 28 ++++++++++++++++++++--------
1 file changed, 20 insertions(+), 8 deletions(-)

Index: linux-2.6.35.y/arch/arm/mm/cache-v6.S
===================================================================
--- linux-2.6.35.y.orig/arch/arm/mm/cache-v6.S
+++ linux-2.6.35.y/arch/arm/mm/cache-v6.S
@@ -196,6 +196,10 @@ ENTRY(v6_flush_kern_dcache_area)
* - end - virtual end address of region
*/
v6_dma_inv_range:
+#ifdef CONFIG_DMA_CACHE_RWFO
+ ldrb r2, [r0] @ read for ownership
+ strb r2, [r0] @ write for ownership
+#endif
tst r0, #D_CACHE_LINE_SIZE - 1
bic r0, r0, #D_CACHE_LINE_SIZE - 1
#ifdef HARVARD_CACHE
@@ -204,6 +208,10 @@ v6_dma_inv_range:
mcrne p15, 0, r0, c7, c11, 1 @ clean unified line
#endif
tst r1, #D_CACHE_LINE_SIZE - 1
+#ifdef CONFIG_DMA_CACHE_RWFO
+ ldrneb r2, [r1, #-1] @ read for ownership
+ strneb r2, [r1, #-1] @ write for ownership
+#endif
bic r1, r1, #D_CACHE_LINE_SIZE - 1
#ifdef HARVARD_CACHE
mcrne p15, 0, r1, c7, c14, 1 @ clean & invalidate D line
@@ -211,10 +219,6 @@ v6_dma_inv_range:
mcrne p15, 0, r1, c7, c15, 1 @ clean & invalidate unified line
#endif
1:
-#ifdef CONFIG_DMA_CACHE_RWFO
- ldr r2, [r0] @ read for ownership
- str r2, [r0] @ write for ownership
-#endif
#ifdef HARVARD_CACHE
mcr p15, 0, r0, c7, c6, 1 @ invalidate D line
#else
@@ -222,6 +226,10 @@ v6_dma_inv_range:
#endif
add r0, r0, #D_CACHE_LINE_SIZE
cmp r0, r1
+#ifdef CONFIG_DMA_CACHE_RWFO
+ ldrlo r2, [r0] @ read for ownership
+ strlo r2, [r0] @ write for ownership
+#endif
blo 1b
mov r0, #0
mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
@@ -256,12 +264,12 @@ v6_dma_clean_range:
* - end - virtual end address of region
*/
ENTRY(v6_dma_flush_range)
- bic r0, r0, #D_CACHE_LINE_SIZE - 1
-1:
#ifdef CONFIG_DMA_CACHE_RWFO
- ldr r2, [r0] @ read for ownership
- str r2, [r0] @ write for ownership
+ ldrb r2, [r0] @ read for ownership
+ strb r2, [r0] @ write for ownership
#endif
+ bic r0, r0, #D_CACHE_LINE_SIZE - 1
+1:
#ifdef HARVARD_CACHE
mcr p15, 0, r0, c7, c14, 1 @ clean & invalidate D line
#else
@@ -269,6 +277,10 @@ ENTRY(v6_dma_flush_range)
#endif
add r0, r0, #D_CACHE_LINE_SIZE
cmp r0, r1
+#ifdef CONFIG_DMA_CACHE_RWFO
+ ldrlob r2, [r0] @ read for ownership
+ strlob r2, [r0] @ write for ownership
+#endif
blo 1b
mov r0, #0
mcr p15, 0, r0, c7, c10, 4 @ drain write buffer

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