[alsa-devel] Headset driver detection problem during bootup

Takashi Iwai tiwai at suse.de
Tue Aug 23 15:52:47 CEST 2011

At Sat, 20 Aug 2011 22:21:10 +0900,
anish singh wrote:
> adding more information and experts on alsa.
> On Fri, Aug 19, 2011 at 9:23 PM, anish singh
> <anish198519851985 at gmail.com> wrote:
> > I need some suggestions for below situation:
> >
> > Headset if it is inserted before the device is powered up is
> > now detected by forcefully calling the interrupt handler in
> > the probe function of the headset driver.
> Headset is detected in our andorid device by using a detect gpio
>  which is turned on when headset is inserted.If the headset
>  is inserted right from very beginging i.e. before device is even
>  turned on then we forcefully call the handler and thereby in
>  handler we check if gpio is turned on or not and do the rest
> of things.
> > Once the handler is called then we find out if the headset
> > is there or not using gpio and then normal detection happens
> >
> > Is it the right way to detect the device during power-up?
> Does not linux have any other way of doing this which i may
> be missing? How this is handled in the case of ALSA jack i.e.
> the jack drivers which is using alsa framework for detection?
> Android doesn't use ALSA framework for reporting JACK.

Judging from the source code, the likely problem is that the driver
doesn't initialize the switch-state in input device.  The switch-state
is updated only when GPIO IRQ comes up.


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