[alsa-devel] HDMI codec, way forward?

[Vinod Koul]

On Wed, Oct 21, 2015 at 03:37:47PM +0100, Russell King - ARM Linux wrote:
> On Wed, Oct 21, 2015 at 04:10:31PM +0200, Takashi Iwai wrote:
> > On Wed, 21 Oct 2015 16:03:07 +0200,
> > Russell King - ARM Linux wrote:
> > > It's only the point if you can code it up properly, which from what I
> > > read in that file, it isn't.
> > 
> > An idea can fly without coding, too :)
> > 
> > > Build the i915 DRM drivers as a module, load up the system, and then
> > > try removing the i915 DRM module and see what happens to the audio part.
> > > For starters, you have no protection what so ever against acomp->ops or
> > > acomp->dev becoming NULL - it's hellishly racy.
> > 
> > Yes, very likely.
> > 
> > > Secondly, you reject the initialisation if acomp->ops isn't set, but you
> > > allow acomp->ops to later become unset by the i915 DRM module being
> > > removed.  If you can cope with acomp->ops being unset at a random point
> > > during the audio driver's use, why can't you cope with it being set at
> > > some random point later?
> > 
> > Setting/unsetting on the fly would be picky because the code does
> > refcounting.  Maybe an easier option is to inc/dec module usage
> > count appropriately in use.
> > 
> > > I don't think this code has been thought through at all.
> > 
> > True, more hardening needed.

I will try to fix this once I am done with Skylake drivers.. Plus adding new
features like ELD in on my plan for this interface

> In any case, this doesn't (and can't) solve the CEC problem, so it's not
> a solution to the problem at hand.

Sorry am not sure I follow the reasons for that, wouldn't CEC be another
slave in such an interface? I though component fwk did allow us to have
multiple slaves..

-- 
~Vinod