linux-kernel - [PATCH 5.19 0681/1157] iio: dac: ad5764: Fix alignment for DMA safety

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Date:   Mon, 15 Aug 2022 20:00:37 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Nuno Sá <nuno.sa@...log.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.19 0681/1157] iio: dac: ad5764: Fix alignment for DMA safety

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

[ Upstream commit b378722a3e9bb51318c0de7eeb4d71f2fcd6987f ]

____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: 68b14d7ea956 ("staging:iio:dac: Add AD5764 driver")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Acked-by: Nuno Sá <nuno.sa@...log.com>
Link: https://lore.kernel.org/r/20220508175712.647246-53-jic23@kernel.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/iio/dac/ad5764.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/dac/ad5764.c b/drivers/iio/dac/ad5764.c
index d235a8047ba0..26c049d5b73a 100644
--- a/drivers/iio/dac/ad5764.c
+++ b/drivers/iio/dac/ad5764.c
@@ -56,13 +56,13 @@ struct ad5764_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);
 };
 
 enum ad5764_type {
-- 
2.35.1