[PATCH] SPI: spi bounce buffer has a minimum length

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: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 94f5e8ed83a7..1168ef015887 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -522,7 +522,8 @@ int spi_sync(struct spi_device *spi, struct spi_message *message)
 }
 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;