[alsa-devel] [Intel-gfx] [PATCH 0/4 V7] Power-well API implementation for Haswell

[Takashi Iwai]

At Sun, 7 Jul 2013 19:59:33 -0400,
Wang xingchao wrote:
> 
> On Sat, Jul 06, 2013 at 08:20:59AM +0200, Takashi Iwai wrote:
> > > >> >> > drm-intel-next. I'll show up in the next linux-next and I'll forward it to
> > > >> >> > Dave for mergin into drm-next in roughly 2 weeks.
> > > >> >>
> > > >> >> So today I unblacklisted the audio modules on one of my Haswell
> > > >> >> machines and booted it with i915.disable_power_well=1. I only have an
> > > >> >> eDP output (it doesn't have audio) and I see the power well is
> > > >> >> enabled. This is wrong, the power well should be disabled since we
> > > >> >
> > > >> > right, if no application using audio it should be in runtime suspend mode.
> > > >> > And maybe your system didnot enable runtime suspend by default, would you
> > > >> > tell me the output below?
> > > >> > cat /sys/devices/pci0000:00/0000:00:03.0/power/control
> > > >>
> > > >> It says "on".
> > > >
> > > > would you change it to "auto" and test again.
> > > > Runtime power save should be enabled with "auto".
> > > 
> > > Doesn't solve the problem. Should I open a bug report somewhere?
> > > Having the power well enabled prevents some power saving features from
> > > the graphics driver.
> > 
> > Is the HD-audio power-saving itself working?  You can check it via
> > watching /sys/class/hwC*/power_{on|off}_acct files.
> 
> I have two Haswell boards, one with "auto" power-save setting, the other one
> has setting "on". Here's the power_on/off_acct values:
> 1) with control setting "auto"
> power_on_acct 14328
> power_off_acct 3231848
> 2) with control setting "on"
> power_on_acct 6330528 
> power_off_acct 0
> 
> So for the second one, power is always on.

Hm, this is the power account per codec, thus its behavior is
basically independent from the controller's PM capability.
If this doesn't change, it means that the codec power saving isn't
activated by some reason.  Check whether power_save parameter is set
to a positive value.


Takashi

> 
> Paulo, would you check with your BIOS version? 
> At least i found BIOS 131 has the default setting "on" while BIOS 128 has
> "auto" setting.
> 
> thanks
> --xingchao
> > 
> > power_save option has to be adjusted appropriately.  Note that many
> > DEs change this value dynamically per AC-cable plug/unplug depending
> > on the configuration, and often it's set to 0 (= no power save) when
> > AC-cable is plugged.
> > 
> > 
>