linux-kernel - Re: Nokia N900 sound driver and ECI GPIOs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20170102092921.GC6728@pali>
Date:   Mon, 2 Jan 2017 10:29:21 +0100
From:   Pali Rohár <pali.rohar@...il.com>
To:     Jarkko Nikula <jarkko.nikula@...mer.com>
Cc:     Pavel Machek <pavel@....cz>, Tony Lindgren <tony@...mide.com>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        Eduardo Valentin <edubezval@...il.com>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        Nishanth Menon <nm@...com>, Sebastian Reichel <sre@...nel.org>,
        Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
        joerg Reisenweber <joerg@...nmoko.org>,
        linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Nokia N900 sound driver and ECI GPIOs

On Monday 02 January 2017 11:01:48 Jarkko Nikula wrote:
> Hi
> 
> On 01/02/2017 12:36 AM, Pavel Machek wrote:
> >> 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.
> > 
> Multibutton ECI headset support using GPIO was planned during early in
> HW design phase but wasn't implemented for the actual product. I don't
> remember was it due no actual product requirement for it or GPIO based
> implementation was not reliable. If I remember correctly ECI protocol
> carries information by shorting mic bias to ground at some 1 kHz rate so
> trying to detect those pulses by SW won't work too well without hard
> real-time OS.
> 
> Even ECI is not implemented in final product the production HW still has
> two switches to route mic bias to voltage detection circuit, tv-out or
> codec. One of the switches is statically driven because only codec or
> tv-out route is needed. See commit 31164c7cf119 ("ASoC: omap: rx51: Add
> headset support")

I know about two gpio switches (TVOUT_EN and ECI_SWITCH=182). But
nothing about gpio 178, which looks like third switch. That statically
driven is gpio 182.

> > I'd like to get detection of headset button presses to work in recent
> > kernels, but could not figure it out :-(.
> > 
> My vague memory doesn't tell how basic button press detection was
> implemented in Maemo kernel. Was it codec, same voltage detection
> circuit than ECI or some another GPIO? I don't even remember did we
> implement it for the MeeGo N900 developer edition :-(

In Maemo 2.6.28 kernel is detection of pressing one button headset. It
is implemented in nokia-av.c and rx51.c files.

I started porting that code to mainline kernel, but I stopped at that
unknown gpio 178.

-- 
Pali Rohár
pali.rohar@...il.com