On Tue, Oct 6, 2009 at 8:38 PM, Takashi Iwai <tiwai@xxxxxxx> wrote: > At Tue, 6 Oct 2009 14:17:40 +0200, > Harald Welte wrote: >> >> Hi all, >> >> On Tue, Oct 06, 2009 at 08:01:40AM +0200, Takashi Iwai wrote: >> >> > > As you describe, we implement it with self-reschedule workqueue, acting >> > > like a timer. >> > > Is there some advice to implement timer-like task, I tested with timer and >> > > it will crash the driver. >> > >> > Right, you can't call it in a softirq. >> > >> > A few problems, however: >> > - present variable should be in struct via_spec, instead of a static >> > variable in update_hp_jack_state(). >> >> I agree >> > - This mechanism is unconditionally invoked on VT1708 although, in >> > theory, you can have a hardware that doesn't need HP jack detection >> >> Yes, Logan/Li/Lydia: If we generate this kind of workaround with a timer, >> it should only be used on those particular chips that absolutely need it. > > As far as I see, the code is only for VT1708, so it's already specific > to the codec chip. But, even with this chip, you might have a pin > configuration that doesn't need the HP jack detection. > Yes, it's only for VT1708, and HP exists on most cases, and so HP jack detection are needed. And present will put into via_spec. >> > - Waking up each 100ms for the *whole* time is really bad regarding >> > the power-saving; can't it be optimized? >> >> I would personally actually suggest to simply not support headphone plug events >> in case you are using such a [buggy?] chipset that does not support them. >> >> I mean, what do you gain from that event? It's not something super-important. >> >> waking up unconditionally every 100ms is really a too high burden on the >> battery life. >> >> Another option might be to make it a module load time parameter, so people >> can choose if they actually want to pay the high power/batyery price for this >> small feature. > > Yes. > > Basically, if we can drop the analog-loopback feature, the HP jack > probing can be simplified very much. The probing is needed only when > the PCM is opened/prepared and running. It can be implemented in a > similar way for the volume-update procedure at PCM trigger. > And, during PCM running, (relatively) high-frequent polling isn't so > critical. > > > thanks, > > Takashi > I know that jack detect on VT1708 that do not support unsolicited response is weird, but it's for customer request (and so are some other patches:), we just have to do something. I think it's good in open/close callback, I'll update. About self-reschedule workqueue, maybe there are some other choices, or should we keep using it? _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
