> -----Original Message----- > From: Takashi Iwai [mailto:tiwai@xxxxxxx] > Sent: Wednesday, July 17, 2013 10:22 PM > To: David Henningsson > Cc: Paulo Zanoni; Wang, Xingchao; alsa-devel@xxxxxxxxxxxxxxxx; Daniel Vetter; > daniel.vetter@xxxxxxxx; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Wang xingchao; > Girdwood, Liam R; Jin, Gordon > Subject: Re: [alsa-devel] [PATCH 0/4 V7] Power-well API > implementation for Haswell > > At Wed, 17 Jul 2013 16:05:43 +0200, > David Henningsson wrote: > > > > On 07/17/2013 04:00 PM, Takashi Iwai wrote: > > > At Wed, 17 Jul 2013 10:31:26 -0300, > > > Paulo Zanoni wrote: > > >> > > >> 2013/7/17 Wang, Xingchao <xingchao.wang@xxxxxxxxx>: > > >>> > > >>> > > >>>> -----Original Message----- > > >>>> From: Takashi Iwai [mailto:tiwai@xxxxxxx] > > >>>> Sent: Wednesday, July 17, 2013 4:18 PM > > >>>> To: Wang, Xingchao > > >>>> Cc: Paulo Zanoni; alsa-devel@xxxxxxxxxxxxxxxx; Daniel Vetter; > > >>>> daniel.vetter@xxxxxxxx; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Wang > > >>>> xingchao; Girdwood, Liam R; david.henningsson@xxxxxxxxxxxxx > > >>>> Subject: Re: [alsa-devel] [PATCH 0/4 V7] Power-well > > >>>> API implementation for Haswell > > >>>> > > >>>> At Wed, 17 Jul 2013 08:03:38 +0000, Wang, Xingchao wrote: > > >>>>> > > >>>>> > > >>>>> > > >>>>>> -----Original Message----- > > >>>>>> From: Takashi Iwai [mailto:tiwai@xxxxxxx] > > >>>>>> Sent: Wednesday, July 17, 2013 3:34 PM > > >>>>>> To: Wang, Xingchao > > >>>>>> Cc: Paulo Zanoni; alsa-devel@xxxxxxxxxxxxxxxx; Daniel Vetter; > > >>>>>> daniel.vetter@xxxxxxxx; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Wang > > >>>>>> xingchao; Girdwood, Liam R; david.henningsson@xxxxxxxxxxxxx > > >>>>>> Subject: Re: [alsa-devel] [PATCH 0/4 V7] Power-well > > >>>>>> API implementation for Haswell > > >>>>>> > > >>>>>> At Wed, 17 Jul 2013 02:52:41 +0000, Wang, Xingchao wrote: > > >>>>>>> > > >>>>>>> Hi Takashi/Paulo, > > >>>>>>> > > >>>>>>>>>> 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. > > >>>>>>>> > > >>>>>>>> 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. > > >>>>>>>> > > >>>>>>> [Wang, Xingchao] Paulo used a new Ultrabook board with charger > > >>>>>>> connected, > > >>>>>> and see the default parameter "auto=on". > > >>>>>>> In such scenario, power-well is always occupied by Display > > >>>>>>> audio controller. Moreover, in this board, if no external > > >>>>>>> monitors connected, It's > > >>>>>> using internal eDP and totally no audio support. Power-well > > >>>>>> usage in such case also blocks some eDP features as Paulo told me. > > >>>>>>> > > >>>>>>> So I think it's not a good idea to break the rule of power > > >>>>>>> policy when charger > > >>>>>> connected but it's necessary to add support in this particular case. > > >>>>>>> Takashi, do you think it's acceptable to let Display audio > > >>>>>>> controller/codec > > >>>>>> suspend in such case? > > >>>>>> > > >>>>>> Do you mean the driver enables the powersave forcibly? > > >>>>> > > >>>>> Yes. I mean call pm_runtime_allow() for the power-well HD-A > controller. > > >>>>> > > >>>>>> Then, no, not in general. > > >>>>>> > > >>>>>> If the default parameter of autopm is the problem, this should > > >>>>>> be changed, instead of forcing the policy in the driver. > > >>>>>> > > >>>>>> OTOH, the audio codec's powersave policy is governed by the > > >>>>>> power_save option and it's set up dynamically by the desktop system. > > >>>>>> We shouldn't override it in the driver. > > >>>>>> > > >>>>>> If the power well *must* be off when only an eDP is used (e.g. > > >>>>>> otherwise the hardware doesn't work properly), then it's a > > >>>>>> different story. Is it the case? And what exactly would be the > > >>>>>> problem? > > >>>>> In the eDP only case, no audio is needed for the HD-A > > >>>>> controller, so it's > > >>>> wasting power in current design. > > >>>>> I think Paulo or Daniel could explain more details on the impact. > > >>>> > > >>>> Consuming more power is the expected behavior. What else? > > >>>> > > >>>> > > >>>>>> If it's the case, controlling the power well based on the > > >>>>>> runtime PM is likely a bad design, as it relies on the parameter user > sets. > > >>>>>> (And remember that the power-saving of the audio can be > > >>>>>> disabled completely via Kconfig, too.) > > >>>>> From audio controller's point of view, if it's asked be active, > > >>>>> it needs power > > >>>> and should request power-well from gfx side. > > >>>>> In above case, audio controller should not be active but user > > >>>>> set it be > > >>>> "active". > > >>>> > > >>>> By setting the autopm "on", user expects that no runtime PM happens. > > >>>> In other words, the audio controller must be kept active as long > > >>>> as this parameter is set. And this is the parameter user > > >>>> controls, and not what the driver forcibly sets. > > >>> > > >>> Okay, become clear now. :) > > >>> So I think the conflict for Paulo becomes, in eDP caes, if audio is active > and requested power-well, some eDP feature was under impact? > > >>> Paulo, would you clarify this in more details? > > >> > > >> On our driver we try to disable the power well whenever possible, > > >> as soon as possible. We don't change our behavior based on power AC > > >> or other user-space modifiable behavior (except the > > >> i915.disable_power_well Kernel option). If the power well is not > > >> disabled we can't enable some features, like PSR (panel self > > >> refresh, and eDP feature) or PC8, which is another power-saving > > >> feature. This will also make our QA procedures a lot more complex > > >> since when we want to test specific features (e.g., PSR, PC8) we'll > > >> have to disconnect the AC adapter or run scripts. So the > > >> behavior/predictability of our driver will be based on the Audio driver > power management policies. > > > > > > So all missing feature are about the power saving? > > > > > >> I am not so experienced with general Linux Power Management code, > > >> so maybe the way the Audio driver is behaving is just the usual > > >> way, but I have to admit I was expecting the audio driver would > > >> only require the power well when it is actually needed, and release > > >> it as soon as possible. > > > > > > It would behave so, if all setups are for power-saving. > > > > > > But, in your case, the runtime PM control attribute shows "on"; it > > > implies that the runtime PM is effectively disabled, thus disabling > > > power well is also impossible (because it would require turning off > > > the audio controller, too). > > > > So, if the machine only has an eDP (which has no audio function in > > itself, right?) and never HDMI, DP output because there are no such > > physical ports, the audio controller has no function. > > Maybe we can, before doing anything else, ask the video driver first > > if this is the case, and if so, never create the sound card at all, > > and just leave things the way the video driver wants? > > Well, doesn't BIOS mark HDMI/DP audio pins as unused? Then the audio > driver won't create any instances. Of course, we can optimize such a case, > indeed. As I know, the eDP only case doesnot mean no HDMI/DP support. User would plug in HDMI/DP monitor at any time. So diable audio controller totoally is not a good idea. :(. Paulo, is that correct for you case? --xingchao > > > Takashi _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
