[alsa-devel] [PATCH 0/4] More aggressive PM for HD-audio

[Takashi Iwai]

At Wed, 18 Mar 2015 20:34:34 +0100,
David Henningsson wrote:
> 
> 
> 
> On 2015-03-18 09:50, Takashi Iwai wrote:
> > Hi,
> >
> > here is a patchset for supporting more aggressive PM for HD-audio.
> > This allows to change the power state of each widget more dynamically
> > with jack and stream states.  It's activated only when the codec
> > driver (or via sysfs or f/w patch) sets codec->power_mgmt flag.
> 
> Cool. Could you elaborate on how the power_mgmt flag interacts with the 
> power_save module parameter (which, on Ubuntu, is set dynamically based 
> on AC power or not)? I e, does it make sense to test this both with and 
> without power_save enabled?
> 
> Also I assume power_save_controller should not matter, right?

The new stuff basically works independently from traditional
power_save and power_save_controller options.  But, you can think it's
on top of power_save stuff, i.e. trying to power on/off of each widget
in the codec while the codec itself is powered on by power_save.

Hierarchy is something like:
  power_mgmt  (managing D0/D3 of each codec widget)
    --> power_save  (managing D0/D3 of FG node of the codec)
      --> power_save_controller  (managing D0/D3 of HDA controller)


Takashi