On 05/19/2011 07:36 PM, Benjamin Herrenschmidt wrote:
On Wed, 2011-05-18 at 16:24 -0500, Eric Van Hensbergen wrote:
  
For BGP, it is convenient for 'kmalloc' to come back with 32-byte
aligned units for torus DMA

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
---
 arch/powerpc/include/asm/page_32.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/page_32.h b/arch/powerpc/include/asm/page_32.h
index 68d73b2..fb0a7ae 100644
--- a/arch/powerpc/include/asm/page_32.h
+++ b/arch/powerpc/include/asm/page_32.h
@@ -9,7 +9,7 @@
 
 #define VM_DATA_DEFAULT_FLAGS	VM_DATA_DEFAULT_FLAGS32
 
-#ifdef CONFIG_NOT_COHERENT_CACHE
+#if defined(CONFIG_NOT_COHERENT_CACHE) || defined(CONFIG_BGP)
 #define ARCH_DMA_MINALIGN	L1_CACHE_BYTES
 #endif
    
Is DMA cache coherent on BG/P ? That's odd for a 4xx base :-)
  

Actually DMA sends invalidate requests to the snoop unit(L2 level).
BGP SoC is a bit different from other 4xx base.

Some details can be found in
www.scc.acad.bg/documentation/team.pdf

- kaz

Cheers,
Ben.



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