[alsa-devel] [ASoC] Missing shutdown() vectors in ASoC

[Liam Girdwood]

On Tue, 2007-06-12 at 17:44 +0530, Nobin Mathew wrote:
> Liam
> 
> I am trying to implement shutdown in ASoC
> 
> /* dapm stream operations */
> #define SND_SOC_DAPM_STREAM_NOP			0x0
> #define SND_SOC_DAPM_STREAM_START		0x1
> #define SND_SOC_DAPM_STREAM_STOP		0x2
> #define SND_SOC_DAPM_STREAM_SUSPEND		0x4
> #define SND_SOC_DAPM_STREAM_RESUME		0x8
> #define SND_SOC_DAPM_STREAM_PAUSE_PUSH	0x10
> #define SND_SOC_DAPM_STREAM_PAUSE_RELEASE	0x20
> 
> 
> Is there any need to add stream operation called
> SND_SOC_DAPM_STREAM_SHUTDOWN even though this has no effect no the
> system behaviour.
> 
> Instead we can use SND_SOC_DAPM_STREAM_SUSPEND.
> Is this OK.
> 
> is there any better way to implement suspend?, i think suspend will be
> a copy of remove() function.
> 

I assume your looking to shutdown the codec to a low power state without
removing the driver ?

If so, SND_SOC_DAPM_STREAM_* operations all act upon stream and path
based widgets (stream and path domain from soc-dapm.h). That is, they
will always power up/down widgets that are actively used in the playback
or capture of audio. This happens automatically at the end of
playback/capture. The wont power down the codec domain.

Atm, the codec power domain (VRef, Vmid) is only affected by signalling
a dapm device event. This happens at probe/remove and suspend/resume atm
for most codecs, although some codecs can alter their Vmid/Vref settings
as part of stream/path domain power changes (as above, e.g. WM8753
changes Vmid from 50k @ SNDRV_CTL_POWER_D0 to 500k SNDRV_CTL_POWER_D3)

Fwiw, I've already added the shutdown function in the new ppc-dev
branch. All component drivers will contain a struct device_driver and
inherit it's features. More on this later today, for the moment the
latest soc.h is here :-

http://opensource.wolfsonmicro.com/cgi-bin/gitweb/gitweb.cgi?p=linux-2.6-asoc;a=blob_plain;f=include/sound/soc.h;hb=ppc-dev

and pxa-i2s driver is here fyi :-

http://opensource.wolfsonmicro.com/cgi-bin/gitweb/gitweb.cgi?p=linux-2.6-asoc;a=blob_plain;f=sound/soc/pxa/pxa2xx-i2s.c;hb=ppc-dev


Liam