Commit fa19c303 authored by David Lechner's avatar David Lechner Committed by Jonathan Cameron
Browse files

iio: make IIO_DMA_MINALIGN minimum of 8 bytes 



Add a condition to ensure that IIO_DMA_MINALIGN is at least 8 bytes.
On some 32-bit architectures, IIO_DMA_MINALIGN is 4. In many cases,
drivers are using this alignment for buffers that include a 64-bit
timestamp that is used with iio_push_to_buffers_with_ts(), which expects
the timestamp to be aligned to 8 bytes. To handle this, we can just make
IIO_DMA_MINALIGN at least 8 bytes.

Reviewed-by: default avatarNuno Sá <nuno.sa@analog.com>
Signed-off-by: default avatarDavid Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20250507-iio-introduce-iio_declare_buffer_with_ts-v6-1-4aee1b9f1b89@baylibre.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent 666eae6c

include/linux/iio/iio.h

+8 −1
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/device.h>

#include <linux/cdev.h>

#include <linux/compiler_types.h>

#include <linux/minmax.h>

#include <linux/slab.h>

#include <linux/iio/types.h>

/* IIO TODO LIST */
@@ -775,8 +776,14 @@ static inline void *iio_device_get_drvdata(const struct iio_dev *indio_dev) 
 * to in turn include IIO_DMA_MINALIGN'd elements such as buffers which

 * must not share  cachelines with the rest of the structure, thus making

 * them safe for use with non-coherent DMA.

 *

 * A number of drivers also use this on buffers that include a 64-bit timestamp

 * that is used with iio_push_to_buffer_with_ts(). Therefore, in the case where

 * DMA alignment is not sufficient for proper timestamp alignment, we align to

 * 8 bytes instead.

 */

#define IIO_DMA_MINALIGN ARCH_DMA_MINALIGN

#define IIO_DMA_MINALIGN MAX(ARCH_DMA_MINALIGN, sizeof(s64))



struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv);



/* The information at the returned address is guaranteed to be cacheline aligned */