ubuntu-phone team mailing list archive

[David Henningsson <david.henningsson@xxxxxxxxxxxxx>]

On 08/27/2013 02:19 PM, Daniel Holbach wrote:
> Hello David,
> 
> On 27.08.2013 14:14, David Henningsson wrote:
>>  == For porters: if you need to do the same ==
>>
>> Unfortunately, this means some additional work for porters, because you
>> need to write UCM mixer files. What's worse, UCM is lacking good
>> documentation. For that reason, I hesitated somewhat before deciding to
>> actually use UCM at all, but it's the closest we have to a standard for
>> setting up mixers on embedded devices right now.
>>
>> But to give you a two-minute crash course in UCM and how it's used in
>> Ubuntu Touch - start by having a look in
>> /usr/share/alsa/ucm/apq8064-tabla-snd-card/ directory (shipped with
>> alsa-lib). You'll need to create a similar directory for your device.
>> You'll find the right directory name if you look in /proc/asound/cards.
>>
>> Second, look at apq8064-tabla-snd-card.conf. Rename and copy into your
>> own UCM directory. If you're making a tablet image (that can't make
>> voice calls), you can remove the VoiceCall part (and the corresponding
>> file).
>>
>> Third, look at the HiFi file. This is where all fun happens. Notice the
>> device names, which are hardcoded into telepathy-ofono and need to
>> match: "Speaker", "Earpiece" and "Headphone" for playback, plus
>> "Handset" and "Headset" for recording.
>>
>> Fourth, if you need voice calls, also look at the VoiceCall file. Btw,
>> the verb names "HiFi" and "VoiceCall" also need to match.) This is
>> largely empty, because the mixer setup is handled by the Audio HAL, but
>> there is a twist here that took a while to get right: For PulseAudio's
>> UCM to work, it needs to open a PCM device. However, at the time where
>> UCM tests this, the voice call is not yet set up. So, you might need to
>> set up the mixer just a little, so that the PCM can open. (On desktops,
>> PCM can always open, regardless of mixer state. This is not always true
>> on embedded devices, that are using ASoC.) It's a bonus if you can find
>> a PCM that actually plays back audio, because then you can get
>> notification sounds while on the phone.
>>
>> And this concludes the two minute crash course - happy porting!
> 
> could we add something like this (maybe even verbatim) to
> https://wiki.ubuntu.com/Touch/PortingFlippedInProgress?

I added a link to this message in the "Further reading" section. Maybe I
should write something more complete for another day, also when I know a
few more problems that porters run into - after all, I only know about
the 2 - 4 devices Canonical supports.

-- 
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic