linux-kernel - Re: [PATCH v3 2/4] i2c: omap: implement workaround for handling invalid BB-bit values

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Date:	Tue, 25 Nov 2014 03:09:13 +0300
From:	Alexander Kochetkov <al.kochet@...il.com>
To:	Tony Lindgren <tony@...mide.com>
Cc:	Kevin Hilman <khilman@...nel.org>, Felipe Balbi <balbi@...com>,
	Wolfram Sang <wsa@...-dreams.de>,
	linux-omap <linux-omap@...r.kernel.org>,
	linux-i2c@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/4] i2c: omap: implement workaround for handling invalid BB-bit values


24 нояб. 2014 г., в 23:05, Alexander Kochetkov <al.kochet@...il.com> написал(а):

> Something (u-boot, may be) leave the bus in the wrong state.
> Really strange.

Actually something wrong with i2c-pullups on i2c.1 bus on fault boards.
May be these are boards without pull-ups?
All beagles doesn't have internal pull-ups on i2c.1 since u-boot 2011.x.

Here is the bug in the u-boot related to beagle:
http://git.denx.de/?p=u-boot.git;a=commit;h=04e2a13336f0e507ef416bbede3be92b79c46594

Yes, I made fix, but keep that in mind.

For example one of the boards (omap3-beagle):
http://status.armcloud.us/boot/omap3-beagle/job/next/kernel/next-20141124/defconfig/arm-omap2plus_defconfig/
http://status.armcloud.us/boot/omap3-beagle,legacy/job/next/kernel/next-20141124/defconfig/arm-omap2plus_defconfig/
http://status.armcloud.us/boot/omap3-beagle/job/next/kernel/next-20141124/defconfig/arm-multi_v7_defconfig/

has following warning message in the u-boot log:
> U-Boot 2014.07 (Aug 21 2014 - 11:03:05)
> 
> OMAP3530-GP ES3.0, CPU-OPP2, L3-165MHz, Max CPU Clock 600 MHz
> OMAP3 Beagle board + LPDDR/NAND
> ....
> Beagle Rev C1/C2/C3
> Timed out in wait_for_event: status=1000
> Check if pads/pull-ups of bus 1 are properly configured

Also beagle schematic has following log entry for A3:
4. Added optional pullup resistors on I2C2_SCL and I2C_SDA into the layout.

Is the fault beagle is pre A3 revision?

I can't tell anything about second one board (omap3-overo-tobi), because I could not get it schematic.

And how you have i2c.1 working without pull-ups I don't know.

Alexander.

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