Re: Nokia N900 sound driver and ECI GPIOs

From: joerg Reisenweber <joerg@openmoko.org>
To: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: "Pali Rohár" <pali.rohar@gmail.com>,
	"Pavel Machek" <pavel@ucw.cz>,
	"Jarkko Nikula" <jarkko.nikula@bitmer.com>,
	"Tony Lindgren" <tony@atomide.com>,
	"Eduardo Valentin" <edubezval@gmail.com>,
	"Lars-Peter Clausen" <lars@metafoo.de>,
	"Aaro Koskinen" <aaro.koskinen@iki.fi>,
	"Nishanth Menon" <nm@ti.com>,
	"Sebastian Reichel" <sre@kernel.org>,
	"Ivaylo Dimitrov" <ivo.g.dimitrov.75@gmail.com>,
	linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Nokia N900 sound driver and ECI GPIOs
Date: Mon, 02 Jan 2017 16:51:50 +0100	[thread overview]
Message-ID: <4227364.xK0WtP2gcZ@saturn> (raw)
In-Reply-To: <a132c193-5c00-14cb-91bf-abb86eac01d6@ti.com>

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On Mon 02 January 2017 16:36:38 Peter Ujfalusi wrote:
> On 01/02/2017 02:58 PM, Pali Rohár wrote:
> > On Monday 02 January 2017 14:53:44 Peter Ujfalusi wrote:
> >> On 01/02/2017 10:51 AM, Pali Rohár wrote:
> >>> On Monday 02 January 2017 10:34:34 Peter Ujfalusi wrote:
> >>>> On 01/02/2017 12:36 AM, Pavel Machek wrote:
> >>>>> Are there multi-button headsets compatible with N900?
> >>>> 
> >>>> Not sure if n900 is capable of handling ECI communication, n9 was. In
> >>>> n9
> >>>> the PMIC/Audio chip had an ECI core integrated afaik
> >>> 
> >>> In N9 it is handled by twl5030 chip? Is there documentation for that
> >>> ECI/ACI part? N900 has twl4030 so we need some chip documentation for
> >>> adding support for N900...
> >> 
> >> n9 has twl5031 and the documentation is not public. But the kernel
> >> source from Nokia have the driver under drivers/mfd/twl5031-aci.c It is
> >> using the ECI stack to report the changes.
> >> twl4030 and twl5030 does not have support for ECI, only twl5031.
> > 
> > Ok, so Nokia N900's audio chip (twl4030) does not have support for ECI.
> 
> TLV320AIC34 (two of them) on n900 to be precise, n9 uses twl5031 and
> tlv320dac33.
> 
> > But still as Jarkko wrote there could be an option to supports ECI via
> > GPIO and ADC.
> 
> Yes, there is the option, but w/o documentation on the ECI protocol it
> is not going to be easy. And I'm sure there were a (good) reason the
> n900 does not support ECI. If it could be done in a stable way the
> product would have support for it.

Don't you think the missing docs and the missing support in N900 might have 
the same reason: copyright issues that forbid both in FOSS?

maybe my little investigation you find at http://neo900.org/stuff/joerg/ECI/ 
might help re protocol low level.

> 
> > And there is still mysterious gpio 178 (RX51_ECI_SWITCH_1_GPIO) which
> > could help us?
> 
> Yeah, that is something I have no idea what it is for. It could be that
> the schema is using different pin mode for it? It might worth looking at
> the TRM on which pin the gpio_178 can go out and look for the possible
> modes? Most likely waste of time...

We did this, the pin is mot listed in schematics under none of the possible 
names or pin number (AA3)
Looks to me like a R&D change done late, similar to the USB PHY.

jOERG
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