[PATCH v5 0/9] dmaengine: Support bus widths of 32 bytes and above

[Nuno Sá]

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 v5:
- Drop the "Move enum dma_slave_buswidth to a new header" patch and the
  include/linux/dma/engine/{types,widthmask}.h split. The bus width
  type and helpers now live in linux/dmaengine.h, next to
  enum dma_slave_buswidth, as both consumers and providers use them
  (Vinod, Frank).
- Patch 1:
  - Move dma_buswidth_mask_t and the bus width helpers into
    linux/dmaengine.h and drop the linux/bitops.h include.
  - Document that dma_bus_width_set{,_many}() add to the mask, like
    __set_bit(), so the caller initializes it (Andy).
  - Drop Andy's Acked-by given the header rework.
- Patch 2-8:
  - Drop the linux/dma/engine/widthmask.h include.
- Patch 8:
  - Include linux/dmaengine.h in spi-dw.h instead of
    linux/dma/engine/types.h.
- Link to v4: https://patch.msgid.link/20260911-dmaengine-support-wider-dma-masks-v4-0-72b8fd4cc78e@xxxxxxxxxx

---
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                            |  24 ++-
 drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c     |  37 ++--
 drivers/dma/qcom/gpi.c                             |  11 +-
 drivers/dma/stm32/stm32-dma3.c                     |  33 ++--
 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                          | 199 +++++++++++++++++++--
 sound/core/pcm_dmaengine.c                         |  20 ++-
 10 files changed, 295 insertions(+), 67 deletions(-)
---
base-commit: 511afae96d89847f753fcab6b3a597f0281be9d5
change-id: 20260615-dmaengine-support-wider-dma-masks-5aac12497e27
--

Thanks!
- Nuno Sá