Re: [PATCH 6/9] Input: surface3 - Fix padding for DMA safe buffers.

[Jonathan Cameron <jic23@kernel.org>]

On Sun, 27 Nov 2022 14:41:13 +0000
Jonathan Cameron <jic23@kernel.org> wrote:

> 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.
> 
> Presumably this part is little used on boards where this could actually
> matter so this is mostly about removing code that might be coppied
> elsewhere.
> 
> Fixes: 4feacbc24eea ("Input: add new driver for the Surface 3")
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>

Sigh. Sunday afternoon incompetence on my part...

Dmitry, if everything else is fine with this series I can resend this
or if you are feeling generous feel free to fix it up whilst applying ;)

Jonathan

> ---
>  drivers/input/touchscreen/surface3_spi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/input/touchscreen/surface3_spi.c b/drivers/input/touchscreen/surface3_spi.c
> index 1da23e5585a0..6c884fc2b332 100644
> --- a/drivers/input/touchscreen/surface3_spi.c
> +++ b/drivers/input/touchscreen/surface3_spi.c
> @@ -32,7 +32,7 @@ struct surface3_ts_data {
>  	struct input_dev *pen_input_dev;
>  	int pen_tool;
>  
> -	u8 rd_buf[SURFACE3_PACKET_SIZE]		____cacheline_aligned;
> +	u8 rd_buf[SURFACE3_PACKET_SIZE] __aligned(ARCH_KMALLOC_MINALIGN;

Missing bracket.

>  };
>  
>  struct surface3_ts_data_finger {