Re: [PATCH v2 05/10] i2c: rcar: refactor setup of a msg

From: Magnus Damm <magnus.damm@gmail.com>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Linux-I2C <linux-i2c@vger.kernel.org>,
	SH-Linux <linux-sh@vger.kernel.org>,
	Simon Horman <horms@verge.net.au>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
	Kuninori Morimoto <kuninori.morimoto.gx@gmail.com>
Subject: Re: [PATCH v2 05/10] i2c: rcar: refactor setup of a msg
Date: Wed, 18 Nov 2015 02:18:00 +0000	[thread overview]
Message-ID: <CANqRtoS0tFtjNcB=gP5xKNzMW2_41rxAydOcZM1+fOSjfCaM7w@mail.gmail.com> (raw)
In-Reply-To: <20151117070053.GA952@tetsubishi>

Hi Wolfram,

On Tue, Nov 17, 2015 at 4:00 PM, Wolfram Sang <wsa@the-dreams.de> wrote:
> Hi Laurent,
>
>> Sorry for bringing bad news, but as with v1, this patch breaks ADV7511
>> detection on my Koelsch board. Reverting it on top of the series fixes the
>> problem.
>
> In v1, patch 5/9 was breaking. I hope in v2, it is 6/10 and not 5/10 as
> you replied to (patch 1/10 is the new one)? This bug is strange enough,
> but 5/10 breaking would be extremly crazy.
>
>> You'll find the dmesg and trace logs with your debugging patch applied
>> attached to this e-mail in two versions, one with the whole series applied (-
>> bad) and one with this patch additionally reverted on top of the series (-
>> good).
>
> Thanks for doing this. I'll think about it some more, but it may be that
> I am running out of ideas without being able to connect a scope. Would
> it be possible to exchange our Koelsch and Lager boards for a while? Or
> is your multimedia work Koelsch dependant?

Swapping boards is of course one option, but shouldn't it also be
possible to reproduce the issue by creating a similar hardware setup
using loopback adapters? The problem is that you cannot reproduce it
on your current hardware, right?

Judging by the Koelsch schematics port EXIO_C has GP6_22/GP6_23 routed
as SD2_CD_3/SC2_WP_3 that may be possible to repurpose as
IIC1_SCL_C/IIC1_SDA_C. So if you want to try an IIC master device on
Koeslch with the I2C2 devices that hold the ADV7511 chip then you
should be able to use those ZEBAX adapters and loopback wires. If you
want to sniff the I2C2 signals on Koelsch then the I2C2 bus is exposed
to EXIO_A and EXIO_D.

On Lager it seems that the GP5_5/GP_6 pins with the I2C2 bus for the
ADV7511 chip has more flexible configuration, so using either IIC or
I2C should be possible. You can sample those pins on EXIO_A with the
ZEBAX break out adapter.

And either way you should be able to compare the results of the I2C
and IIC masters with GPIO using the bitbang implementation.

Feel free to let me know exactly what the problem is and I will do my
best to help you out!

Thanks,

/ magnus