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[9/9] Input: elants - Fix suspect DMA buffer alignment

Message ID 20221127144116.1418083-10-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: 00f73f97527f ("Input: elants_i2c - use DMA safe i2c when possible")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Daniel Hung-yu Wu <hywu@google.com>
---
 drivers/input/touchscreen/elants_i2c.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/drivers/input/touchscreen/elants_i2c.c b/drivers/input/touchscreen/elants_i2c.c
index 879a4d984c90..7ad58518c651 100644
--- a/drivers/input/touchscreen/elants_i2c.c
+++ b/drivers/input/touchscreen/elants_i2c.c
@@ -184,7 +184,7 @@  struct elants_data {
 	bool keep_power_in_suspend;
 
 	/* Must be last to be used for DMA operations */
-	u8 buf[MAX_PACKET_SIZE] ____cacheline_aligned;
+	u8 buf[MAX_PACKET_SIZE] __aligned(ARCH_KMALLOC_MINALIGN);
 };
 
 static int elants_i2c_send(struct i2c_client *client,