[PATCH 5.18 0605/1095] iio: adc: ltc2496: Fix alignment for DMA safety

Greg Kroah-Hartman
2022-08-15T21:37:40Z

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