On Sat, Sep 27, 2014 at 10:28:47AM +0100, Russell King - ARM Linux wrote:
> On Sat, Sep 27, 2014 at 10:54:43AM +0200, Maxime Ripard wrote:
> > The previous code was relying on the fact that the slave_caps were to be
> > defined on a per channel basis.
> >
> > However, this proved to be a bit overkill, since every driver filling these so
> > far were hardcoding it, disregarding which channel was actually given.
> >
> > Add these capabilities to the dma_device structure, so that drivers can just
> > provide them at probe time, and be done with it.
>
> This is also buggy for the same reason as patch 6.
Indeed
> The only way to do this is to either have a flag day, fixing all drivers
> at once (which isn't going to happen) or leave the caps code as-is, and
> provide a library function which drivers can hook into the caps callback
> which retrieves the information from dma_device.
>
> That way, DMA engine drivers which are using the new method can just
> install the new function, and those which haven't been updated with
> capabilities can carry on as they are, and are detectable to drivers.
Which is pretty much the current behaviour, isn't it?
> What would be acceptable is to have the DMA engine registration function
> spot the lack of DMA caps function and print a warning at boot to
> encourage people to add it.
That would be an option too.
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
On Wed, Oct 01, 2014 at 10:27:05AM +0200, Maxime Ripard wrote:
> On Sat, Sep 27, 2014 at 10:28:47AM +0100, Russell King - ARM Linux wrote:
> > The only way to do this is to either have a flag day, fixing all drivers
> > at once (which isn't going to happen) or leave the caps code as-is, and
> > provide a library function which drivers can hook into the caps callback
> > which retrieves the information from dma_device.
> >
> > That way, DMA engine drivers which are using the new method can just
> > install the new function, and those which haven't been updated with
> > capabilities can carry on as they are, and are detectable to drivers.
>
> Which is pretty much the current behaviour, isn't it?
Yes, because the ASoC code has obviously already thought about this and
solved the lack-of-caps-function problem in a way that permits existing
solutions to continue working.
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