Re: [PATCH v6 0/9] dmaengine: Support bus widths of 32 bytes and above

["Nuno Sá" <nuno.sa@analog.com>]

On Wed, Oct 14, 2026 at 03:19:10PM +0100, Nuno Sá wrote:
> The DMA engine slave capabilities advertise the supported source and
> destination bus widths through src_addr_widths / dst_addr_widths. These
> are plain u32 bitmasks where a set bit's position equals the
> corresponding enum dma_slave_buswidth value, e.g.
> DMA_SLAVE_BUSWIDTH_4_BYTES sets bit 4.
> 
> The consequence is that widths of 32 bytes and above cannot be
> represented at all: DMA_SLAVE_BUSWIDTH_32/64/128_BYTES would need bits
> 32, 64 and 128, which do not fit in a u32. Hardware with wider data
> paths is becoming common, so add a representation that can express these
> widths while still using enum dma_slave_buswidth.
> 
> This series switches consumers and a small set of producers to the new
> bus width capabilities, represented by a dma_buswidth_mask_t modeled
> after dma_cap_mask_t. The legacy dma_device u32 fields are kept for now
> so the remaining DMA controller drivers can be converted incrementally:
> dma_async_device_register() folds a legacy-only producer's u32 into the
> mask, so consumers only ever have to look at the mask.
> 
> Once the remaining producers are converted, the legacy dma_device
> src/dst_addr_widths fields can be removed as a final cleanup.
> 
> This issue was discussed before here:
> 
> https://lore.kernel.org/dmaengine/abkoXXbaxaiqbBuX@vaman/
> 
> Changes in v6:
> - Patch 1:
>   - Prefix the bus width helpers with dmaengine_ (Frank).
>   - Drop the wrapper macros taking the address of their mask arguments.
>     The helpers are now static inline functions taking a
>     dma_buswidth_mask_t pointer (Frank).
>   - Drop a stray blank line in dma_get_slave_caps() (Frank).
> - Patch 2-8:
>   - Use the renamed helpers, passing the masks by pointer.
> - Link to v5: https://patch.msgid.link/20261009-dmaengine-support-wider-dma-masks-v5-0-4c4e63a7a1af@analog.com
> 
> ---
> Nuno Sá (9):
>       dmaengine: Support bus widths of 32 bytes and above
>       dmaengine: dma-axi-dmac: Use bus width capability helpers
>       dmaengine: dw-axi-dmac: Use bus width capability helpers
>       dmaengine: qcom: gpi: Use bus width capability helpers
>       dmaengine: stm32-dma3: Use bus width capability helpers
>       iio: buffer-dmaengine: Use dma_slave_caps bus width accessors
>       ALSA: pcm_dmaengine: Use dma_slave_caps bus width helpers
>       spi: dw: Use dma_slave_caps bus width helpers
>       dmaengine: Drop legacy bus width fields from dma_slave_caps
> 
>  drivers/dma/dma-axi-dmac.c                         |  13 +-
>  drivers/dma/dmaengine.c                            |  23 ++-
>  drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c     |  39 +++--
>  drivers/dma/qcom/gpi.c                             |  11 +-
>  drivers/dma/stm32/stm32-dma3.c                     |  37 ++--
>  drivers/iio/buffer/industrialio-buffer-dmaengine.c |  15 +-
>  drivers/spi/spi-dw-dma.c                           |   7 +-
>  drivers/spi/spi-dw.h                               |   3 +-
>  include/linux/dmaengine.h                          | 188 +++++++++++++++++++--
>  sound/core/pcm_dmaengine.c                         |  20 ++-
>  10 files changed, 289 insertions(+), 67 deletions(-)
> ---
> base-commit: 42c31fec1ca76b8b5f7759def122d418dff2cd4b
> change-id: 20260615-dmaengine-support-wider-dma-masks-5aac12497e27
> --
> 
> Thanks!
> - Nuno Sá
> 

Hi Vinod, pinging this one before resend. Already got the rb  tag from Frank on the
first patch. If anything left to do, let me know please.

- Nuno Sá