Re: Nokia N900 sound driver and ECI GPIOs

From: Pavel Machek
Date: Sun Jan 01 2017 - 17:37:04 EST


Hi!

> I'm looking at original Maemo N900 2.6.28 sound driver and GPIOs which
> controls A/V jack detection.
>
> For reference source code of that driver can be found e.g. at alsa-devel
> ML [1] [2] or in my linux-n900 git tree, branch v2.6.28-nokia [3].
>
> In that sound/soc/omap/rx51.c code is function rx51_set_eci_switches()
> which configures 2 gpios: RX51_ECI_SWITCH_1_GPIO = gpio 178 and
> RX51_ECI_SWITCH_2_GPIO = gpio 182 based on "eci mode" input parameter.
>
> But in mainline kernel code [4] [5] there is no information about gpio 178
> (as RX51_ECI_SWITCH_1_GPIO) and gpio 182 is called as just "eci-switch".
> More interesting part is that "eci-switch" gpio is not used in whole
> mainline code. It is just referenced in Nokia N900 DTS [4]. Looks like
> sound driver in mainline kernel is incomplete.
>
> Jarkko, you are listed as original author of that driver. Do you (or
> anybody else) remember what that rx51_set_eci_switches() function is
> doing? And what gpio 178 controls? I was even not able to find gpio 178
> in RX-51 Schematics [6].
>
> And do you know something about Nokia ECI headsets supports for Nokia
> N900. Looks like there is already some kernel code but support for ECI
> bus or multibuttons headset is missing.

What does "ECI" mean?

I'd like to get detection of headset button presses to work in recent
kernels, but could not figure it out :-(.

Are there multi-button headsets compatible with N900?

Best regards,
Pavel


--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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