[alsa-devel] [PATCH 00/11] drm/i915: LPE audio runtime PM and multipipe

[Takashi Iwai]

On Tue, 25 Apr 2017 22:27:19 +0200,
ville.syrjala at linux.intel.com wrote:
> 
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> I was wondering why my VLV no longer runtime suspended, and after some
> thinking I decided it had to be the LPE audio preventing it. Turns out
> I was right, so here's my attempt at fixing it.
> 
> And while looking at the code I couldn't help but notice that it
> couldn't actually handle multiple pipes playing back audio at the
> same time. And even having multiple displays active even if only
> one was playing audio was probably a recipe for failure. So I
> tried to fix that by registering a separate PCM device for each
> pipe.
> 
> Note that the patch subjects may not reflect the subsystem
> very well since most of these straddle the border between drm
> and alsa. I think I just slapped on drm/i915 to most where
> there was no clear winner.

A nice patchset, thanks for working on it!

One slight concern (other than the jack issue Pierre reported) is the
incompatible behavior from the current version.  With the pipe-based
multiple streams, user would need to choose another one even if the
device has a single HDMI output, which is pretty common on BYT/CHV
tablets.

Maybe it's no big problem as the users are still limited at the
moment.  Or, we may need to handle a bit differently, e.g. assigning
the PCM stream dynamically per hotplug.

In anyway, with the support of multi streams, alsa-lib config needs to
be updated.


Takashi