[alsa-devel] HDMI codec, way forward?

[Russell King - ARM Linux]

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.

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

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