Re: [PATCH v4 01/10] dmaengine: Move enum dma_slave_buswidth to a new header

[Nuno Sá]

On Tue, Oct 06, 2026 at 02:59:16AM -0500, Frank Li wrote:
> On Tue, Oct 06, 2026 at 07:36:06AM +0100, Nuno Sá wrote:
> > On Sat, 2026-10-03 at 19:59 -0500, Frank Li wrote:
> ...
> > >
> > > There are already include bitmap.h, and use
> > >
> > > typedef struct { DECLARE_BITMAP(bits, DMA_TX_TYPE_END); } dma_cap_mask_t;
> > >
> > > Suppose all DMA Engine consumer will use it to do some check. So I think
> > > needn't split it as indivial version.
> >
> > Are we sure all consumers are making use of dma_cap_mask?
> 
> Some legacy user check it. Supposed needn't check it after get channel.
> I am working new API to check it to avoid direct access it.
> 
> > In fact the only function
> > depending on bitmap.h is the one clearing the cap_mask. But stepping a bit back,
> > bitmap.h was the original proposal from Andy so the idea was to have the new
> > widthmask (this one indeed heavily uses bitmaps) already as a split. And with it,
> > came types.h given that the DMA enum needs to be used from both consumers and
> > providers.
> 
> Supposed provider is super set, which can include consume part.

Yes but also look the below note on the consumers.

> 
> > And note that consumers might want the header without actually needing the
> > bus width API so the separation kind of made sense to me.
> > Then, as a follow up the idea was to also split the cap_mask API into it's own header
> > with a backing include in the main consumer header.
> >
> > So if we all agree with the above, I guess the current series does not really has to
> > change. I see 3 ways:
> >
> > * Just go back some versions before and have all of it in dmaengine.h
> > * The current form
> > * s/engine/consumer on the current proposal include/linux/dma/engine/*
> 
> I think we can put include/linux/dmaengine.h now. The split/move need more
> work. I already sent some patches.
> 

Ok, to be sure we're 100% on the same side, plan for now is to add the
bus width API directly in include/linux/dmaengine.h?

- Nuno Sá

> Frank
> 
> >
> > - Nuno Sá
> >
> > >
> > > Frank
> > >
> > > > where it's indeed required. Besides bitmap.h there are might be more headers
> > > > that "include half of the world" which should be avoided in every header file.
> > > >
> > > > --
> > > > With Best Regards,
> > > > Andy Shevchenko
> > > >
> > > >