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SubjectRe: [PATCH 5/7 v2] dma: sh: use an integer slave ID to improve API compatibility
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On Mon, 2012-07-16 at 08:37 +0200, Guennadi Liakhovetski wrote:
> On Mon, 16 Jul 2012, Vinod Koul wrote:
>
> > On Thu, 2012-07-05 at 12:29 +0200, Guennadi Liakhovetski wrote:
> > > diff --git a/include/linux/sh_dma.h b/include/linux/sh_dma.h
> > > index a79f10a..4e83f3e 100644
> > > --- a/include/linux/sh_dma.h
> > > +++ b/include/linux/sh_dma.h
> > > @@ -27,10 +27,10 @@ struct sh_dmae_slave {
> > > * a certain peripheral
> > > */
> > > struct sh_dmae_slave_config {
> > > - unsigned int slave_id;
> > > - dma_addr_t addr;
> > > - u32 chcr;
> > > - char mid_rid;
> > > + int slave_id;
> > > + dma_addr_t addr;
> > > + u32 chcr;
> > > + char mid_rid;
> > > };
> > why would you want to keep your own slave_id and addr fields when they
> > are already provided in struct dma_slave_config.
>
> Modifying the driver's API would break all its clients.
rightly so, they need to be moved too.

>
> > Also while at it, what
> > would be the use of last tow fields, what do they describe?
>
> They tell the driver how the channel has to be configured to support this
> specific client. They are values of two specific registers. In fact, CHCR
> means exactly that - CHannel Control Register.
what exactly does the channel control register do in shdma? Should shdma
driver deduce this value rather than client giving it?
Same question for mid_rid?


--
~Vinod



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