Re: [PATCH v2 9/9] dmaengine: Drop legacy bus width fields from dma_slave_caps

[Frank Li <Frank.li@oss.nxp.com>]

On Mon, Aug 10, 2026 at 04:06:50PM +0100, Nuno Sá wrote:
> All users of dma_get_slave_caps() that inspect bus width capabilities now
> use the bitmap helpers.
>
> Hence, remove the legacy u32 src_addr_widths and dst_addr_widths fields
> from struct dma_slave_caps and stop copying the dma_device masks into
> them.
>
> Note the legacy u32 src_addr_widths and dst_addr_widths fields in struct
> dma_device are kept for now as every DMA controller driver setting them
> still has to be converted to the new helpers. dma_get_slave_caps() keeps
> folding those masks into the bitmaps it returns so unconverted producers
> continue to work during the transition.
>
> Signed-off-by: Nuno Sá <nuno.sa@analog.com>
> ---

Reviewed-by: Frank Li <Frank.Li@nxp.com>

>  drivers/dma/dmaengine.c   |  2 --
>  include/linux/dmaengine.h | 16 ++--------------
>  2 files changed, 2 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index a80a84cf87eb..36e9b6ddd88d 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -592,7 +592,6 @@ int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
>  	if (!device->directions)
>  		return -ENXIO;
>
> -	caps->src_addr_widths = device->src_addr_widths;
>  	if (bitmap_empty(device->src_bus_widths, DMA_SLAVE_BUSWIDTH_MAX)) {
>  		bitmap_zero(caps->src_bus_widths, DMA_SLAVE_BUSWIDTH_MAX);
>  		bitmap_from_arr32(caps->src_bus_widths,
> @@ -602,7 +601,6 @@ int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
>  			    DMA_SLAVE_BUSWIDTH_MAX);
>  	}
>
> -	caps->dst_addr_widths = device->dst_addr_widths;
>  	if (bitmap_empty(device->dst_bus_widths, DMA_SLAVE_BUSWIDTH_MAX)) {
>  		bitmap_zero(caps->dst_bus_widths, DMA_SLAVE_BUSWIDTH_MAX);
>  		bitmap_from_arr32(caps->dst_bus_widths,
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index 8697583e2ed3..4efaa27e9f7e 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -503,9 +503,7 @@ enum dma_residue_granularity {
>   * @src_bus_widths: bitmap of source bus widths the channel supports.
>   *	Width is specified in bytes, e.g. for a channel supporting
>   *	a width of 4 the bitmap should have bit 4 set.
> - * @src_addr_widths: legacy bit mask of source bus widths the channel supports.
>   * @dst_bus_widths: bitmap of destination bus widths the channel supports.
> - * @dst_addr_widths: legacy bit mask of destination bus widths the channel supports.
>   * @directions: bit mask of slave directions the channel supports.
>   *	Since the enum dma_transfer_direction is not defined as bit flag for
>   *	each type, the dma controller should set BIT(<TYPE>) and same
> @@ -524,14 +522,8 @@ enum dma_residue_granularity {
>   * resubmitted multiple times
>   */
>  struct dma_slave_caps {
> -	struct {
> -		DECLARE_DMA_BUS_WIDTHS(src_bus_widths);
> -		u32 src_addr_widths;
> -	};
> -	struct {
> -		DECLARE_DMA_BUS_WIDTHS(dst_bus_widths);
> -		u32 dst_addr_widths;
> -	};
> +	DECLARE_DMA_BUS_WIDTHS(src_bus_widths);
> +	DECLARE_DMA_BUS_WIDTHS(dst_bus_widths);
>  	u32 directions;
>  	u32 min_burst;
>  	u32 max_burst;
> @@ -1922,8 +1914,6 @@ dma_slave_caps_clear_src_width(struct dma_slave_caps *caps,
>  			       enum dma_slave_buswidth width)
>  {
>  	__clear_bit(width, caps->src_bus_widths);
> -	if (width < DMA_SLAVE_BUSWIDTH_32_BYTES)
> -		caps->src_addr_widths &= ~BIT(width);
>  }
>
>  /**
> @@ -1936,8 +1926,6 @@ dma_slave_caps_clear_dst_width(struct dma_slave_caps *caps,
>  			       enum dma_slave_buswidth width)
>  {
>  	__clear_bit(width, caps->dst_bus_widths);
> -	if (width < DMA_SLAVE_BUSWIDTH_32_BYTES)
> -		caps->dst_addr_widths &= ~BIT(width);
>  }
>
>  static inline int __dma_set_bus_widths(unsigned long *bus_widths,
>
> --
> 2.55.0
>