[PATCH 5.19 0694/1157] iio: frequency: ad9523: Fix alignment for DMA safety

Greg Kroah-Hartman
2022-08-16T00:17:29Z

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

[ Upstream commit 8ff2eb625c353b1491d9f89f1dfd52e7aef5734c ]

____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.

Updated help text to 'may' require buffers to be in their own cacheline.

Fixes: cd1678f96329 ("iio: frequency: New driver for AD9523 SPI Low Jitter Clock Generator")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220508175712.647246-66-jic23@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/iio/frequency/ad9523.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/frequency/ad9523.c b/drivers/iio/frequency/ad9523.c
index 942870539268..97662ca1ca96 100644
--- a/drivers/iio/frequency/ad9523.c
+++ b/drivers/iio/frequency/ad9523.c
@@ -287,13 +287,13 @@ struct ad9523_state {
struct mutex lock;

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

static int ad9523_read(struct iio_dev *indio_dev, unsigned int addr)
--
2.35.1