[alsa-devel] Bug in setting channels, related to recent ELD/EDID changes?

[Takashi Iwai]

At Fri, 21 Jan 2011 18:53:31 -0800,
VDR User wrote:
> 
> On Tue, Jan 11, 2011 at 12:47 PM, Anssi Hannula <anssi.hannula at iki.fi> wrote:
> >> First, THANK YOU for addressing this!  However, I have a couple
> >> questions.  Which solution was implemented; a true/false switch
> >> controlling the behavior between the old _working_ method, or the new
> >> ELD restricted one?  Or, this module parameter thing that was
> >> mentioned?
> >>
> >> As a user having to deal with the frustration of this problem, I
> >> absolutely think the true/false switch is the best solution as it's
> >> set-and-forget.  Set it one time, get the behavior you _want_, and not
> >> have to bother with it again.  With the module parameter thing, it
> >> sounds like you have to change module parameters according to what you
> >> want at the moment.  Or is it that the true/false switch is controlled
> >> by a module param?  Maybe I've misinterpreted it but it's not very
> >> clear.
> >
> > Yes, it is a true/false switch controlled by a module parameter.
> >
> >> So I grab alsa git, but how do I use the fix to restore the old behavior?
> >
> > Set the module parameter static_hdmi_pcm of snd-hda-codec-hdmi to 1.
> >
> > For example, by adding this into /etc/modprobe.conf:
> > options snd-hda-codec-hdmi static_hdmi_pcm=1
> >
> > For the record, this is the commit:
> > http://git.kernel.org/?p=linux/kernel/git/tiwai/sound-2.6.git;a=commitdiff;h=5eedd1422c2fc79c2f9ed8b71056b97570f95572
> 
> This appears to not be working properly.  Here are the test results:
> 
> cold boot pc, kernel 2.6.34.7, alsa kernel drivers, receiver off
> eld shows 2 channel stereo (from tv) available
> vdr tuned to hdtv with 5.1 surround audio: no errors from alsa,
> surround channels missing
> vdr tuned to hdtv with 5.1 surround audio, receiver turned on: no
> errors from alsa, surround channels working
> 
> cold boot pc, kernel 2.6.37, alsa snapshot drivers jan.22,2010, receiver off
> eld shows 2 channel stereo (from tv) available
> options snd-hda-codec-hdmi static_hdmi_pcm=1
> vdr tuned to hdtv with 5.1 surround audio: no errors from alsa, some
> surround channels missing
> vdr tuned to hdtv with 5.1 surround audio, receiver turned on: no
> errors from alsa, some surround channels missing
> 
> cold boot pc, kernel 2.6.37, alsa snapshot drivers jan.22,2010, receiver on
> eld shows 8 channels (7.1) available
> vdr tuned to hdtv with 5.1 surround audio: no errors from alsa, some
> surround channels missing
> vdr tuned to hdtv with 5.1 surround audio, receiver turned on: no
> errors from alsa, some surround channels missing
> 
> The HD content I was using was the movie Watchmen.  In all cases where
> "some surround channels missing", it was at a minimum whatever
> channel(s) carry the main audio for the talking/spoken dialog.  All
> (as far as I know, but could be wrong) the background audio seemed to
> be present.
> 
> Could someone please take a look at the workaround patch.  The new
> "static_hdmi_pcm" parameter when set to 1 is supposed to mimic the
> original alsa behavior prior to this eld restriction stuff being added
> but the patch appears to somehow have broken surround sound as
> described above.

Could you put printk() appropriately for showing which values are
requested and which runtime->hw values are actually set for each
working and non-working case?


Takashi