linux-kernel - [PATCH 5.19 0656/1157] iio: adc: mcp320x: Fix alignment for DMA safety

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Date:   Mon, 15 Aug 2022 20:00:12 +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>,
        Michael Welling <mwelling@...e.org>,
        Nuno Sá <nuno.sa@...log.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.19 0656/1157] iio: adc: mcp320x: Fix alignment for DMA safety

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

[ Upstream commit e770f78036ce4327caf285873f4b20564a8b4f0f ]

____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.

Worth noting the fixes tag refers to the same issue being observed
on a platform that probably had only 64 byte cachelines.

Fixes: 0e81bc99a082 ("iio: mcp320x: Fix occasional incorrect readings")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc: Michael Welling <mwelling@...e.org>
Acked-by: Nuno Sá <nuno.sa@...log.com>
Link: https://lore.kernel.org/r/20220508175712.647246-28-jic23@kernel.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/iio/adc/mcp320x.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/adc/mcp320x.c b/drivers/iio/adc/mcp320x.c
index b4c69acb33e3..f3b81798b3c9 100644
--- a/drivers/iio/adc/mcp320x.c
+++ b/drivers/iio/adc/mcp320x.c
@@ -92,7 +92,7 @@ struct mcp320x {
 	struct mutex lock;
 	const struct mcp320x_chip_info *chip_info;
 
-	u8 tx_buf ____cacheline_aligned;
+	u8 tx_buf __aligned(IIO_DMA_MINALIGN);
 	u8 rx_buf[4];
 };
 
-- 
2.35.1