[Gta04-owner] Reliable headset detection with raw values

Paul Kocialkowski contact at paulk.fr
Sat May 24 16:16:04 CEST 2014


Le samedi 24 mai 2014 à 14:55 +0200, Lukas Maerdian a écrit :
> On 24.05.2014 14:14 UTC+0200, Paul Kocialkowski wrote:
> >>> This doesn't make much sense to me.
> >>> Rather than guessing I looked at the code, and the effect of setting 'raw'
> >>> is to bypass
> >>>
> >>> 			buf[i] = (buf[i] * 3 * 1000 *
> >>> 				 twl4030_divider_ratios[i].denominator)
> >>> 				/ (2 * 1023 *
> >>> 				twl4030_divider_ratios[i].numerator);
> >>>
> >>> where 'i' is 7, and twl4030_divider_ratios[7] is
> >>>
> >>> 	{6, 10},	/* CHANNEL 7 */
> >>>
> >>> So this becomes
> >>>    buf[i] * 30000 / 12276
> >>>
> >>> so it rough multiplies the numbers be 2.5.  That shouldn't affect stability
> >>> at all.
> >>
> >> Yes, you're perfectly right, I didn't read twl4030_madc_read_channels
> >> completely and just assumed it was changing the range of values in a
> >> dynamic way (for instance, using calibration), but obviously, I was
> >> wrong. It really did seem like it was improving stability (for instance,
> >> I had values that drastically changed from one reboot to the other, like
> >> 800 to 400, without raw), but then it was late when I did this and I
> >> jumped to conclusions too fast, without learning about the details.
> >>
> >> I'll revert the change in the Replicant 4.2 tree and use thresholds
> >> based on the non-raw values.
> > 
> > Turns out I wasn't so crazy after all! My patch did introduce better
> > stability because the raw element of the request structure wasn't
> > initialized previously, which lead to randomly either raw or processed
> > values, hence the different ranges of values depending on the day, the
> > device, etc.
> > 
> > I've just pushed a patch to fix this in the Replicant 4.2 kernel[0]:
> > commit 2421efd8de974fee6a06e45ca31d4ed6f4805573
> > Author: Paul Kocialkowski <contact at paulk.fr>
> > Date:   Sat May 24 13:08:29 2014 +0200
> > 
> >     twl4030-madc: Request processed values in twl4030_get_madc_conversion
> >     
> >     Not setting the raw parameter in the request causes it to be randomly
> >     initialized to a value that might be different from zero or zero. This leads to
> >     values that are randomly either raw or processed, making it very difficult to
> >     make reliable use of the values.
> >     
> >     Signed-off-by: Paul Kocialkowski <contact at paulk.fr>
> > 
> > I suggest you include that patch in the other kernel trees. I've also
> > proposed a similar patch for mainline, so that this is not an issue for
> > anyone in the future!
> > 
> > By the way, the Replicant kernel is not using raw values anymore, and
> > I've adapted the thresholds[1]:
> > 
> > commit 47d0bd23e540b5fd8dcf4d722a8309d24ce9ee56
> > Author: Paul Kocialkowski <contact at paulk.fr>
> > Date:   Sat May 24 13:15:14 2014 +0200
> > 
> >     gta04-audio: Jack detection thresholds for processed values
> >     
> >     Signed-off-by: Paul Kocialkowski <contact at paulk.fr>
> > 
> > [0]:
> > https://gitorious.org/replicant/kernel_goldelico_gta04/commit/2421efd8de974fee6a06e45ca31d4ed6f4805573
> > [1]:
> > https://gitorious.org/replicant/kernel_goldelico_gta04/commit/47d0bd23e540b5fd8dcf4d722a8309d24ce9ee56
> 
> Thanks for the heads-up!
> I've included the two patches into the Goldelico 3.12-replicant4 kernel
> and Nikolaus might eventually cherry-pick your raw value fix
> (2421efd8de974fee6a06e45ca31d4ed6f4805573) into 3.12.7 and 3.15-rc

Note that the patch is different for 3.15-rc, since the driver was moved
to some other place. The correct one is:
http://marc.info/?l=linux-iio&m=140093393003482&w=2

Perhaps it'll even get integrated in mainline soon, so Nikolaus won't
have to cherry-pick!

-- 
Paul Kocialkowski, Replicant developer

Replicant is a fully free Android distribution

Website:        http://www.replicant.us/
Wiki/Tracker:   http://redmine.replicant.us/
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