On Tue, Apr 26, 2011 at 10:41:05AM +0100, Liam Girdwood wrote:
On Mon, 2011-04-25 at 17:01 -0500, pl bossart wrote:
To prepare next week's ALSA-Asoc meeting, I reviewed Liam's dsp-upstream code, and I am a bit unclear on the 'no_host_mode' supported by some DAIs. Apparently these are regular ALSA PCM substreams, except that there are no data exchanges to/from the host.
Ah, this part is WIP and will not be part of the initial submission. We are currently using this for audio between the MODEM and ABE that does not pass through the CPU.
This is roughly the same thing I've been talking about for digital DAPM links. I've got code which runs at the minute but the implementation sucks too much, should be able to pull out some of the preparation work in the next day or so.
- is this really important that such PCM devices be known in
userspace? Or are they declared only so that ALSA controls are enabled for these streams?
The intention is that userspace apps would know there is no data, but this is probably better discussed at conference. It may also require an alsa-lib update too.
Personally I think we should just hide them, but it's fairly painful to do that immediately due to the ALSA core infrastructure we're using. If we refactor to reduce this or to support masking PCMs in the core this should be less of an issue.