[PATCH 5.18 0649/1095] iio: frequency: ad9523: Fix alignment for DMA safety

[Greg Kroah-Hartman]

From: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>

[ 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@xxxxxxxxxx>
Acked-by: Nuno Sá <nuno.sa@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220508175712.647246-66-jic23@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 a0f92c336fc4..31c97f9f2c1b 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