Re: [PATCH 09/19] dma-buf-map: Add wrapper over memset

[Christian König]

Am 26.01.22 um 21:36 schrieb Lucas De Marchi:
> Just like memcpy_toio(), there is also need to write a direct value to a
> memory block. Add dma_buf_map_memset() to abstract memset() vs memset_io()
>
> Cc: Matt Roper <matthew.d.roper@xxxxxxxxx>
> Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
> Cc: Christian König <christian.koenig@xxxxxxx>
> Cc: linux-media@xxxxxxxxxxxxxxx
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: linaro-mm-sig@xxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
> ---
>   include/linux/dma-buf-map.h | 17 +++++++++++++++++
>   1 file changed, 17 insertions(+)
>
> diff --git a/include/linux/dma-buf-map.h b/include/linux/dma-buf-map.h
> index 3514a859f628..c9fb04264cd0 100644
> --- a/include/linux/dma-buf-map.h
> +++ b/include/linux/dma-buf-map.h
> @@ -317,6 +317,23 @@ static inline void dma_buf_map_memcpy_to(struct dma_buf_map *dst, const void *sr
>   		memcpy(dst->vaddr, src, len);
>   }
>   
> +/**
> + * dma_buf_map_memset - Memset into dma-buf mapping
> + * @dst:	The dma-buf mapping structure
> + * @value:	The value to set
> + * @len:	The number of bytes to set in dst
> + *
> + * Set value in dma-buf mapping. Depending on the buffer's location, the helper
> + * picks the correct method of accessing the memory.
> + */
> +static inline void dma_buf_map_memset(struct dma_buf_map *dst, int value, size_t len)
> +{
> +	if (dst->is_iomem)
> +		memset_io(dst->vaddr_iomem, value, len);
> +	else
> +		memset(dst->vaddr, value, len);
> +}
> +

Yeah, that's certainly a valid use case. But maybe directly add a 
dma_buf_map_memset_with_offset() variant as well when that helps to 
avoid patch #2.

Regards,
Christian.

>   /**
>    * dma_buf_map_incr - Increments the address stored in a dma-buf mapping
>    * @map:	The dma-buf mapping structure