[PATCH 5.19 0674/1157] iio: dac: ad5421: Fix alignment for DMA safety

Greg Kroah-Hartman
2022-08-16T04:35:41Z

From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

[ Upstream commit d2b240d3d31c66df4d2da54c75ff8e27a0e006c3 ]

____cacheline_aligned is an insufficient guarantee for non-coherent DMA
on platforms with 128 byte cachelines above L1. Switch to the updated
IIO_DMA_MINALIGN definition.

Update the comment to include 'may'.

Fixes: 5691b23489db ("staging:iio:dac: Add AD5421 driver")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220508175712.647246-46-jic23@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/iio/dac/ad5421.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/dac/ad5421.c b/drivers/iio/dac/ad5421.c
index eedf661d32b2..7644acfd879e 100644
--- a/drivers/iio/dac/ad5421.c
+++ b/drivers/iio/dac/ad5421.c
@@ -72,13 +72,13 @@ struct ad5421_state {
struct mutex lock;

/*
- * DMA (thus cache coherency maintenance) requires the
+ * DMA (thus cache coherency maintenance) may require the
* transfer buffers to live in their own cache lines.
*/
union {
__be32 d32;
u8 d8[4];
- } data[2] ____cacheline_aligned;
+ } data[2] __aligned(IIO_DMA_MINALIGN);
};

static const struct iio_event_spec ad5421_current_event[] = {
--
2.35.1