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@xxxxxxxxx>
Tested-by: Helmut Klein <hgkr.klein@xxxxxxxxx>
---
v2:
- switch to much simpler version as suggested by Kevin Hilman <khilman@xxxxxxxxxxxx>
- 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
--
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