[PATCH v2] mmc: sdio: fix alignment issue in struct sdio_func

[Heiner Kallweit <hkallweit1@gmail.com>]

Certain 64-bit systems (e.g. Amlogic Meson GX) require buffers to be
used for DMA to be 8-byte-aligned. struct sdio_func has an embedded
small DMA buffer not meeting this requirement.
Testing an extension to meson-gx driver for switching to descriptor
chain mode broke SDIO therefore. Aligning tmpbuf to a 8-byte
boundary fixed the driver behavior.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Tested-by: Helmut Klein <hgkr.klein@gmail.com>
---
v2:
- switch to much simpler version as suggested by Kevin Hilman <khilman@baylibre.com>
- adjust commit message
---
 include/linux/mmc/sdio_func.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/mmc/sdio_func.h b/include/linux/mmc/sdio_func.h
index aab032a6..65d90f76 100644
--- a/include/linux/mmc/sdio_func.h
+++ b/include/linux/mmc/sdio_func.h
@@ -53,7 +53,8 @@ struct sdio_func {
 	unsigned int		state;		/* function state */
 #define SDIO_STATE_PRESENT	(1<<0)		/* present in sysfs */
 
-	u8			tmpbuf[4];	/* DMA:able scratch buffer */
+	/* take care of proper alignment for DMA on certain 64-bit systems */
+	u8 __aligned(8)		tmpbuf[4];	/* DMA:able scratch buffer */
 
 	unsigned		num_info;	/* number of info strings */
 	const char		**info;		/* info strings */
-- 
2.12.1