[PATCH 6.1 106/197] iio: adc: ad_sigma_delta: ensure proper DMA alignment

Greg Kroah-Hartman
2024-02-20T21:05:03Z

From: Nuno Sa <nuno.sa@analog.com>

commit 59598510be1d49e1cff7fd7593293bb8e1b2398b upstream.

Aligning the buffer to the L1 cache is not sufficient in some platforms
as they might have larger cacheline sizes for caches after L1 and thus,
we can't guarantee DMA safety.

That was the whole reason to introduce IIO_DMA_MINALIGN in [1]. Do the same
for the sigma_delta ADCs.

[1]: https://lore.kernel.org/linux-iio/20220508175712.647246-2-jic23@kernel.org/

Fixes: 0fb6ee8d0b5e ("iio: ad_sigma_delta: Don't put SPI transfer buffer on the stack")
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240117-dev_sigma_delta_no_irq_flags-v1-1-db39261592cf@analog.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/iio/adc/ad_sigma_delta.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/include/linux/iio/adc/ad_sigma_delta.h
+++ b/include/linux/iio/adc/ad_sigma_delta.h
@@ -8,6 +8,8 @@
#ifndef __AD_SIGMA_DELTA_H__
#define __AD_SIGMA_DELTA_H__

+#include <linux/iio/iio.h>
+
enum ad_sigma_delta_mode {
AD_SD_MODE_CONTINUOUS = 0,
AD_SD_MODE_SINGLE = 1,
@@ -99,7 +101,7 @@ struct ad_sigma_delta {
* 'rx_buf' is up to 32 bits per sample + 64 bit timestamp,
* rounded to 16 bytes to take into account padding.
*/
- uint8_t tx_buf[4] ____cacheline_aligned;
+ uint8_t tx_buf[4] __aligned(IIO_DMA_MINALIGN);
uint8_t rx_buf[16] __aligned(8);
};