linux-kernel - [PATCH 5.18 0643/1095] iio: dac: ltc2688: Fix alignment for DMA safety

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Message-Id: <20220815180455.996050240@linuxfoundation.org>
Date:   Mon, 15 Aug 2022 20:00:42 +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 5.18 0643/1095] iio: dac: ltc2688: Fix alignment for DMA safety

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

[ Upstream commit 2030708377a219b548a9a36da57d3852382baf1d ]

____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: 832cb9eeb931 ("iio: dac: add support for ltc2688")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Acked-by: Nuno Sá <nuno.sa@...log.com>
Link: https://lore.kernel.org/r/20220508175712.647246-60-jic23@kernel.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/iio/dac/ltc2688.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/dac/ltc2688.c b/drivers/iio/dac/ltc2688.c
index 2f9c384885f4..04ec38b1cad1 100644
--- a/drivers/iio/dac/ltc2688.c
+++ b/drivers/iio/dac/ltc2688.c
@@ -91,10 +91,10 @@ struct ltc2688_state {
 	struct mutex lock;
 	int vref;
 	/*
-	 * DMA (thus cache coherency maintenance) requires the
+	 * DMA (thus cache coherency maintenance) may require the
 	 * transfer buffers to live in their own cache lines.
 	 */
-	u8 tx_data[6] ____cacheline_aligned;
+	u8 tx_data[6] __aligned(IIO_DMA_MINALIGN);
 	u8 rx_data[3];
 };
 
-- 
2.35.1