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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>,
        =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        =?UTF-8?q?Nuno=20S=C3=A1?= <nuno.sa@analog.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.19 0650/1157] iio: adc: ltc2496: Fix alignment for DMA safety
Date:   Mon, 15 Aug 2022 20:00:06 +0200
Message-Id: <20220815180505.743485775@linuxfoundation.org>
In-Reply-To: <20220815180439.416659447@linuxfoundation.org>
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From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

[ Upstream commit 1673b7ca2dc1fb3b8d7c94a112496c02d34ae449 ]

____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: e4c5c4dfaa88 ("iio: adc: new driver to support Linear technology's ltc2496")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220508175712.647246-22-jic23@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/iio/adc/ltc2496.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/ltc2496.c b/drivers/iio/adc/ltc2496.c
index 5a55f79f2574..dfb3bb5997e5 100644
--- a/drivers/iio/adc/ltc2496.c
+++ b/drivers/iio/adc/ltc2496.c
@@ -24,10 +24,10 @@ struct ltc2496_driverdata {
 	struct spi_device *spi;
 
 	/*
-	 * DMA (thus cache coherency maintenance) requires the
+	 * DMA (thus cache coherency maintenance) may require the
 	 * transfer buffers to live in their own cache lines.
 	 */
-	unsigned char rxbuf[3] ____cacheline_aligned;
+	unsigned char rxbuf[3] __aligned(IIO_DMA_MINALIGN);
 	unsigned char txbuf[3];
 };
 
-- 
2.35.1