Re: [PATCH v5 06/10] dmaengine: add API for getting dma controller's quirk

[Shawn Lin]

Hi Vinod,

On 2015/10/5 23:37, Vinod Koul wrote:
> On Mon, Sep 14, 2015 at 07:48:59AM +0800, Shawn Lin wrote:
> > Add dmaengine_get_quirks API for peripheral devices to query
> > quirks if they need it to make special workaround due to broken
> > dma controller design.
> >
> > Signed-off-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>
> > ---
> >
> > Changes in v5: None
> > Changes in v4: None
> > Changes in v3: None
> > Changes in v2: None
> > Changes in v1: None
> >
> >   include/linux/dmaengine.h | 9 +++++++++
> >   1 file changed, 9 insertions(+)
> >
> > diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> > index e2f5eb4..5174ca4 100644
> > --- a/include/linux/dmaengine.h
> > +++ b/include/linux/dmaengine.h
> > @@ -704,6 +704,7 @@ struct dma_device {
> >
> >   	int (*device_config)(struct dma_chan *chan,
> >   			     struct dma_slave_config *config);
> > +	int (*device_get_quirks)(struct dma_chan *chan);
>
> And why do we want to expose this to users? THis doesnt seem right!

Basically I agree not to expose dma's quirk to slave controllers...But, 
the fact I mentioned on cover letter explain the reasons why I have to 
let slave controllers know that they are working with a broken dma. It's 
a dilemma that if we don't want that to be exposed(let slave 
controllers' driver get the info via a API), we have to add broken quirk 
for all of them ,here and there, which seems to be a disaster:(

I would appreciate it if you could give me some suggestions at your 
earliest convenience. :)

> A quirk may exists but should be handled inside the controller driver and do
> appropriate action. You don't tell users or expect them to handle these


--
Best Regards
Shawn Lin

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