linux-kernel - Re: [PATCH v3 1/4] i2c: tegra: implement slave mode

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Date:	Tue, 8 Sep 2015 13:46:21 +0200
From:	Wolfram Sang <wsa@...-dreams.de>
To:	Andrey Danin <danindrey@...l.ru>
Cc:	Stephen Warren <swarren@...dotorg.org>, devicetree@...r.kernel.org,
	devel@...uxdriverproject.org, linux-i2c@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-tegra@...r.kernel.org,
	linux-kernel@...r.kernel.org, ac100@...ts.launchpad.net,
	Laxman Dewangan <ldewangan@...dia.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Russell King <linux@....linux.org.uk>,
	Thierry Reding <thierry.reding@...il.com>,
	Alexandre Courbot <gnurou@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Julian Andres Klode <jak@...-linux.org>,
	Marc Dietrich <marvin24@....de>
Subject: Re: [PATCH v3 1/4] i2c: tegra: implement slave mode


> Sorry for the long delay. I tried to analyze the issue. Attached patch works
> on AC100 (Misha Komarovsky helped me with testing).
> 
> Wolfram could you please try the patch with your environment?

No change, sadly. I don't get slave interrupts.

> Init function is called multuple times. If I2C controller works
> in slave mode, then driver must keep slave registers otherwise
> slave configuration will be reseted.

This patch does not tackle the main issue, though. There should not be a
"slave mode" for the controller. It can be a master and slave
simultaneously and should do the right thing depending on what's
happening on the bus. The Tegra2 manual I have says "The Master can
address the internal slave (for basic testing) or an external 7-bit or
10-bit addressed Slave device." So even a loopback should be possible
(if we trust the manual ;)).


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