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[2/9] Input: ad714x - Fix padding for DMA safe buffers.

Message ID 20221127144116.1418083-3-jic23@kernel.org
State New
Headers show
Series Input: Fix insufficent DMA alignment. | expand

Commit Message

Jonathan Cameron Nov. 27, 2022, 2:41 p.m. UTC 
From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

On some architectures (e.g. arm64), ____cachline_aligned only aligns
to the cacheline size of the L1 cache size. L1_CACHE_BYTES in
arch64/include/asm/cache.h  Unfortunately DMA safety on these
architectures requires the buffer no share a last level cache cacheline
given by ARCH_DMA_MINALIGN which has a greater granularity.
ARCH_DMA_MINALIGN is not defined for all architectures, but when it is
defined it is used to set the size of ARCH_KMALLOC_MINALIGN
to allow DMA safe buffer allocations.

As such the correct alignment requirement is
__aligned(ARCH_KMALLOC_MINALIGN).
This has recently been fixed in other subsystems such as IIO.

Fixes tag is inprecise because there may not have been any architectures
where the two values were different at the time of the earlier fix.

Fixes: c0409feb8689 ("Input: ad714x - use DMA-safe buffers for spi_write()")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Michael Hennerich <michael.hennerich@analog.com>
---
 drivers/input/misc/ad714x.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/drivers/input/misc/ad714x.h b/drivers/input/misc/ad714x.h
index af847b5f0d0e..2b8b901183be 100644
--- a/drivers/input/misc/ad714x.h
+++ b/drivers/input/misc/ad714x.h
@@ -41,7 +41,7 @@  struct ad714x_chip {
 	unsigned product;
 	unsigned version;
 
-	__be16 xfer_buf[16] ____cacheline_aligned;
+	__be16 xfer_buf[16] __aligned(ARCH_KMALLOC_MINALIGN);
 
 };