diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 94f5e8ed83a7a8427105201aaa81f14ff5c710c7..1168ef015887ebddcb6a36852ab39913e05b5394 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;