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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        Lars-Peter Clausen <lars@metafoo.de>,
        =?UTF-8?q?Nuno=20S=C3=A1?= <nuno.sa@analog.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.18 0629/1095] iio: dac: ad5421: Fix alignment for DMA safety
Date:   Mon, 15 Aug 2022 20:00:28 +0200
Message-Id: <20220815180455.463747917@linuxfoundation.org>
In-Reply-To: <20220815180429.240518113@linuxfoundation.org>
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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