From: David Brownell <david-b@pacbell.net>

Someone pointed out that "one cacheline's worth of data" isn't as portable
as might be desired, so this adds a 32-byte floor.

Make sure that spi_write_then_read() can always handle at least 32 bytes of
transfer (total, both directions), minimizing one portability issue.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 drivers/spi/spi.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletion(-)

diff -puN drivers/spi/spi.c~spi-bounce-buffer-has-a-minimum-length drivers/spi/spi.c
--- 25/drivers/spi/spi.c~spi-bounce-buffer-has-a-minimum-length	Mon Apr  3 15:54:24 2006
+++ 25-akpm/drivers/spi/spi.c	Mon Apr  3 15:54:24 2006
@@ -522,7 +522,8 @@ int spi_sync(struct spi_device *spi, str
 }
 EXPORT_SYMBOL_GPL(spi_sync);
 
-#define	SPI_BUFSIZ	(SMP_CACHE_BYTES)
+/* portable code must never pass more than 32 bytes */
+#define	SPI_BUFSIZ	max(32,SMP_CACHE_BYTES)
 
 static u8	*buf;
 
_