Re: [PATCH 5/9] dmaengine: stm32-dma3: Use bus width capability helpers

On Thu, Jul 30, 2026 at 03:23:12PM +0100, Nuno Sá via B4 Relay wrote:
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>
> From: Nuno Sá <[email protected]>
>
> Advertise the controller-wide bus width capabilities through the new
> dma_set_src_bus_widths() and dma_set_dst_bus_widths() helpers.
>
> Also update the per-channel capability callback to clear unsupported
> widths through the dma_slave_caps helpers so the bitmap and
> transitional legacy fields stay in sync.
>
> Signed-off-by: Nuno Sá <[email protected]>
> ---

Reviewed-by: Frank Li <[email protected]>

>  drivers/dma/stm32/stm32-dma3.c | 32 ++++++++++++++++++++------------
>  1 file changed, 20 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/dma/stm32/stm32-dma3.c b/drivers/dma/stm32/stm32-dma3.c
> index 4724e7fa0008..b0365a5b341d 100644
> --- a/drivers/dma/stm32/stm32-dma3.c
> +++ b/drivers/dma/stm32/stm32-dma3.c
> @@ -1469,14 +1469,14 @@ static void stm32_dma3_caps(struct dma_chan *c, struct dma_slave_caps *caps)
>
>         if (!chan->fifo_size) {
>                 caps->max_burst = 0;
> -               caps->src_addr_widths &= ~BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
> -               caps->dst_addr_widths &= ~BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
> +               dma_slave_caps_clear_src_width(caps, DMA_SLAVE_BUSWIDTH_8_BYTES);
> +               dma_slave_caps_clear_dst_width(caps, DMA_SLAVE_BUSWIDTH_8_BYTES);
>         } else {
>                 /* Burst transfer should not exceed half of the fifo size */
>                 caps->max_burst = chan->max_burst;
>                 if (caps->max_burst < DMA_SLAVE_BUSWIDTH_8_BYTES) {
> -                       caps->src_addr_widths &= ~BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
> -                       caps->dst_addr_widths &= ~BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
> +                       dma_slave_caps_clear_src_width(caps, DMA_SLAVE_BUSWIDTH_8_BYTES);
> +                       dma_slave_caps_clear_dst_width(caps, DMA_SLAVE_BUSWIDTH_8_BYTES);
>                 }
>         }
>  }
> @@ -1737,6 +1737,12 @@ static int stm32_dma3_probe(struct platform_device *pdev)
>         u32 master_ports, chan_reserved, i, verr;
>         u64 hwcfgr;
>         int ret;
> +       enum dma_slave_buswidth stm32_dma3_buswidths[] = {
> +               DMA_SLAVE_BUSWIDTH_1_BYTE,
> +               DMA_SLAVE_BUSWIDTH_2_BYTES,
> +               DMA_SLAVE_BUSWIDTH_4_BYTES,
> +               DMA_SLAVE_BUSWIDTH_8_BYTES,
> +       };
>
>         ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
>         if (!ddata)
> @@ -1775,14 +1781,16 @@ static int stm32_dma3_probe(struct platform_device *pdev)
>          * channel, and can only access address at even boundaries, multiple of the buswidth.
>          */
>         dma_dev->copy_align = DMAENGINE_ALIGN_8_BYTES;
> -       dma_dev->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
> -                                  BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
> -                                  BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) |
> -                                  BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
> -       dma_dev->dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
> -                                  BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
> -                                  BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) |
> -                                  BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
> +       ret = dma_set_src_bus_widths(dma_dev, stm32_dma3_buswidths,
> +                                    ARRAY_SIZE(stm32_dma3_buswidths));
> +       if (ret)
> +               return ret;
> +
> +       ret = dma_set_dst_bus_widths(dma_dev, stm32_dma3_buswidths,
> +                                    ARRAY_SIZE(stm32_dma3_buswidths));
> +       if (ret)
> +               return ret;
> +
>         dma_dev->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV) | BIT(DMA_MEM_TO_MEM);
>
>         dma_dev->descriptor_reuse = true;
>
> --
> 2.55.0
>
>