linux-kernel - Re: the dp helper would try to enable the i2c channel for rockchip-edp

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Date:   Thu, 20 Oct 2016 10:02:22 +0200
From:   Tomeu Vizoso <tomeu.vizoso@...labora.com>
To:     Randy Li <randy.li@...k-chips.com>
Cc:     "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        Gustavo Padovan <gustavo.padovan@...labora.co.uk>
Subject: Re: the dp helper would try to enable the i2c channel for rockchip-edp

On 20 October 2016 at 09:38, Randy Li <randy.li@...k-chips.com> wrote:
>
>
> On 10/20/2016 03:18 PM, Tomeu Vizoso wrote:
>>
>> On 19 October 2016 at 15:52, Randy Li <randy.li@...k-chips.com> wrote:
>>>
>>> Hello,
>>>
>>>   Recently, I want to use a eDP panel in my RK3288 platform, but I got
>>> the
>>> following message:
>>>
>>> [    8.935918] i2c i2c-6: of_i2c: modalias failure on /dp@...70000/ports
>>> [    8.936018] rockchip-drm display-subsystem: bound ff970000.dp (ops
>>> rockchip_dp_component_ops [analogix_dp_rockchip])
>>> It try to enable the eDP aux channel and add a new I2C controller, but it
>>> failed then the whole display subsystem is broken, the panel doesn't
>>> power
>>> on either.
>>>
>>>   I hope somebody could figure out what is wrong with it.
>>
>>
>> Hi Randy,
>>
>> you want to debug why the call to of_modalias_node fails.
>>
> But I didn't know who register that I2C controller, as the system only have
> 6 I2C controller(0-5).

Ah, now I remember that the warning is spurious, have just sent a
patch to avoid it with you on Cc ("ARM: dts: rockchip: add i2c-bus
subnode to edp").

Could you please test it out?

Regarding why a 7th I2C adapter is being registered, that's the one
used by the eDP controller, and the code registering it is DRM core
when the analogix driver calls drm_dp_aux_register.

Regarding your problem with DRM not loading properly, you would need
to attach more content from dmesg as the lines you attached doesn't
seem related to it. You can get more debug logs from DRM by booting
with this kernel parameter:

drm.debug=0x1f

Regards,

Tomeu