N900 modem support in 3.18-rc1

Hi,

On Fri, Nov 14, 2014 at 09:54:42PM +0200, Ivaylo Dimitrov wrote:

On 14.11.2014 19:20, Sebastian Reichel wrote:

quoted

The patch looks ok. It does not cleanup the cmt-speech driver for
mainline usage, but it should work. Before adding this driver to the
mainline kernel there should be open source userspace support anyway.

I am aware of that(patch not ready), it's one of the reasons this
patch still sits on gitorious IMO.

libcmtspeechdata was opened by Nokia long ago, so I don't understand what
userspace support (for inclusion of the driver in the mainline kernel that
is) is needed. see https://gitorious.org/meego-cellular/libcmtspeechdata/source/7f8f3ce357513e4849e1bf6d657980a514529c1a:

ah cool. I assumed, that userland stuff is mostly closed.

REed pulseaudio modules that use cmtspeech will be ready sooner than later
(I believe in 2-3 monts from now), see on gitorious how fast we progressed
with -record and -music modules. Sure, -voice module is way more
complicated, but lots of it is already opensourced, we just need to figure
out a couple of DSP algorithms(drc, agc, aec, etc) related to call quality.
But I don't think the driver should wait for those modules to be REed, they
can be used as is even now, in their closed form for testing.

https://gitorious.org/pulseaudio-modules-nemo/jusas-tanuk2-mer-packaging/source/6ed34611b49c99b007f614d9dff4d58369876345:
https://github.com/nemomobile/pulseaudio-module-cmtspeech-n9xx/commits/master

It seems there is already cmtspeech code for pulseaudio?

Unfortunately all my spare time is dedicated to that PA stuff, so
I simply can't cleanup cmtspeech driver and send a patch for
upstreaming. (Pavel, what about you?)

If somebody gets audio working with your driver and documents the
steps needed in userland I will take care of upstreaming the driver.

quoted

Btw. I am aware that this would break existing pulse audio stuff,
but wouldn't it make sense to export a V4L2 device instead of the
custom /dev/cmt_speech ABI?

Not to say that I agree with Pali's reply that working userspace should not
be broken just for the sake of it.

Actually the mainline kernel never implemented that interface, so
there is no regression/break and I don't think introducing userspace
ABI's should be done carelessly - especially when there is also a
standardized interface.

Nokia PA guys did a great job integrating lots of things related to audio
and honestly, I don't see a reason why should we reinvent the wheel. There
is lot more behind the scenes than simple PCM streaming (like audio policies
and routing, sideband audio, speakers protection, etc) and reiplementing all
this using different API wouldn't worth it IMO.

What has speaker protection to do with the modem interface?
Shouldn't this be two different PA modules?

-- Sebastian
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