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[v2,15/92] iio: adc: ad7766: Fix alignment for DMA safety

Message ID 20220508175712.647246-16-jic23@kernel.org (mailing list archive)
State Accepted
Headers show
Series IIO: Fix alignment of buffers for DMA | expand

Commit Message

Jonathan Cameron May 8, 2022, 5:55 p.m. UTC 
From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

____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 reflect the fact DMA safety 'may' require
separate cachelines.

Fixes: aa16c6bd0e09 ("iio:adc: Add support for AD7766/AD7767")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Nuno Sá <nuno.sa@analog.com>
---
 drivers/iio/adc/ad7766.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
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Patch

diff --git a/drivers/iio/adc/ad7766.c b/drivers/iio/adc/ad7766.c
index 51ee9482e0df..3079a0872947 100644
--- a/drivers/iio/adc/ad7766.c
+++ b/drivers/iio/adc/ad7766.c
@@ -45,13 +45,12 @@  struct ad7766 {
 	struct spi_message msg;
 
 	/*
-	 * DMA (thus cache coherency maintenance) requires the
+	 * DMA (thus cache coherency maintenance) may require the
 	 * transfer buffers to live in their own cache lines.
 	 * Make the buffer large enough for one 24 bit sample and one 64 bit
 	 * aligned 64 bit timestamp.
 	 */
-	unsigned char data[ALIGN(3, sizeof(s64)) + sizeof(s64)]
-			____cacheline_aligned;
+	unsigned char data[ALIGN(3, sizeof(s64)) + sizeof(s64)]	__aligned(IIO_DMA_MINALIGN);
 };
 
 /*