Input: ads7846 - make transfer buffers DMA safe
req.sample needs its own cacheline otherwise accessing req.msg fetches
it in again.
Note: This effect doesn't occur if the underlying SPI driver doesn't use
DMA at all.
Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index c24946f..ab51a8db 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -281,17 +281,25 @@
u8 command;
u8 ref_off;
u16 scratch;
- __be16 sample;
struct spi_message msg;
struct spi_transfer xfer[6];
+ /*
+ * DMA (thus cache coherency maintenance) requires the
+ * transfer buffers to live in their own cache lines.
+ */
+ __be16 sample ____cacheline_aligned;
};
struct ads7845_ser_req {
u8 command[3];
u8 pwrdown[3];
- u8 sample[3];
struct spi_message msg;
struct spi_transfer xfer[2];
+ /*
+ * DMA (thus cache coherency maintenance) requires the
+ * transfer buffers to live in their own cache lines.
+ */
+ u8 sample[3] ____cacheline_aligned;
};
static int ads7846_read12_ser(struct device *dev, unsigned command)