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

On Thu, Jul 30, 2026 at 02:34:51PM -0500, Frank Li wrote:
> On Thu, Jul 30, 2026 at 03:23:16PM +0100, Nuno Sá via B4 Relay wrote:
> > [You don't often get email from [email protected]. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
> >
> > From: Nuno Sá <[email protected]>
> >
> > All users of dma_get_slave_caps() that inspect bus width capabilities
> > now use bitmap helpers.
> >
> > Remove the legacy fields from struct dma_slave_caps and stop copying the
> > dma_device legacy masks into them.
> >
> > Keep folding legacy dma_device masks into the returned bitmaps so
> > unconverted DMA controller producers continue to work during the
> > transition.
> 
> which one you kept?

The one in

https://elixir.bootlin.com/linux/v7.1.5/source/include/linux/dmaengine.h#L890

given that we need to update all controllers in drivers/dma before we
can get rid of them. I guess I need better working in the commit
message?

- Nuno Sá

> 
> Frank
> 
> >
> > Signed-off-by: Nuno Sá <[email protected]>
> > ---
> >  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 7be23ba769d0..ee0b8bfc7c97 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 cea57b166dcb..f37a0559ec5f 100644
> > --- a/include/linux/dmaengine.h
> > +++ b/include/linux/dmaengine.h
> > @@ -495,9 +495,7 @@ 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
> > @@ -516,14 +514,8 @@ 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;
> > @@ -1789,8 +1781,6 @@ 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);
> >  }
> >
> >  /**
> > @@ -1803,8 +1793,6 @@ 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
> >
> >