linux-kernel - Re: Nokia N900 - audio TPA6130A2 problems

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]

Date:	Thu, 17 Mar 2016 06:33:14 -0700
From:	Tony Lindgren <tony@...mide.com>
To:	Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
Cc:	Pali Rohár <pali.rohar@...il.com>,
	Sebastian Reichel <sre@...nel.org>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Peter Ujfalusi <peter.ujfalusi@...com>,
	Jarkko Nikula <jarkko.nikula@...mer.com>,
	Lars-Peter Clausen <lars@...afoo.de>,
	linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
	Pavel Machek <pavel@....cz>,
	Aaro Koskinen <aaro.koskinen@....fi>,
	Nishanth Menon <nm@...com>, merlijn@...zup.org
Subject: Re: Nokia N900 - audio TPA6130A2 problems

* Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com> [160317 06:11]:
> Hi,
> 
> On 17.03.2016 15:01, Pali Rohár wrote:
> >On Thursday 17 March 2016 09:56:22 Ivaylo Dimitrov wrote:
> >>Hi,
> >>
> >
> >Is camera on same bus as tpa? Maybe this is reason why camera is
> >non-functional too?
> >
> 
> It doesn't matter, all the i2c busses are missing the pullups.
> 
> >>Will fix the board DTS file later on an will report
> >
> >Thanks for investigation! Is that problem in both DTS and also legacy
> >board code?
> >
> 
> I guess legacy board code does not set i2c pull-ups either, as we
> have that problem since the beginning of time. Anyway, let me first
> check if enabling pullups really solves the issue, I hope to test that in a
> couple of hours when I am back home.
> 
> Or you can do it yourself, it is just a matter of replacing PIN_INPUT with
> PIN_INPUT_PULLUP in https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/omap3-n900.dts?id=refs/tags/v4.5#n199
> for all the 3 ic2 busses

Check the schematics. If the hardware has external pull-ups on a
line then don't enable the internal pull-ups. Otherwise both the
external and intenal pulls are parallel the pull value will be
wrong. My guess is that on n900 all the i2c lines have external
pulls.

Regards,

Tony