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authorDavid Lechner <dlechner@baylibre.com>2025-05-07 23:42:40 +0300
committerJonathan Cameron <Jonathan.Cameron@huawei.com>2025-05-21 16:20:31 +0300
commitfa19c303254bae5b8d105ecdc7d714d092f2adda (patch)
tree42cf5a2de112f882f61c78166f4a5bc39d1013a5
parent666eae6c6dab46cb5023170651286c47a693f661 (diff)
downloadlinux-fa19c303254bae5b8d105ecdc7d714d092f2adda.tar.xz
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: Nuno Sá <nuno.sa@analog.com> Signed-off-by: David 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: Jonathan Cameron <Jonathan.Cameron@huawei.com>
-rw-r--r--include/linux/iio/iio.h9
1 files changed, 8 insertions, 1 deletions
diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index 638cf2420fbd..a574f22398e4 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -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 */