linux-kernel - Re: [PATCH 8/8] drm/bridge: it66121: Allow link this driver as a lib

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Message-ID: <aa4dd247-0eb1-4cda-9284-98da981bd3e1@linux.dev>
Date:   Sat, 18 Nov 2023 01:14:49 +0800
From:   Sui Jingfeng <sui.jingfeng@...ux.dev>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Phong LE <ple@...libre.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Maxime Ripard <mripard@...nel.org>,
        Sui Jingfeng <suijingfeng@...ngson.cn>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Thomas Zimmermann <tzimmermann@...e.de>
Subject: Re: [PATCH 8/8] drm/bridge: it66121: Allow link this driver as a lib

Hi,

On 2023/11/17 17:03, Dmitry Baryshkov wrote:
> On Fri, 17 Nov 2023 at 06:24, Sui Jingfeng <sui.jingfeng@...ux.dev> wrote:
>> Hi,
>>
>> On 2023/11/16 23:23, Dmitry Baryshkov wrote:
>>>>>> Then you will need some way (fwnode?) to
>>>>>> discover the bridge chain. And at the last point you will get into the
>>>>>> device data and/or properties business.
>>>>>>
>>>>> No, leave that chance to a more better programmer and forgive me please,
>>>>> too difficult, I'm afraid of not able to solve. Thanks a lot for the
>>>>> trust!
>>>   From my point of view: no.
>>
>> I respect the fact that the community prefer generic mechanisms.
>> If our approach is not what the community want, can I switch back
>> to my previous solution? I can reduce the duplication of our
>> localized it66121 driver to a minimal, rewrite it until it meets
>> the community's requirement. I know our device looks weird and
>> our approach is not elegant. But at the very least, we could not
>> mess the community's design up by localize. Otherwise, I don't know
>> what is the better approach to solve such a problem.
>>
>> Can I switch back or any other ideas?
> I keep on repeating: create the i2c device from your root device
> driver, which parses BIOS data.
>
This is not my own problems, currently it66121 (but not only) display bridge driver
don't works on X86 either. What we are trying to do is to provide a generic, non-platform
dependent solution. It is not only relevant to my driver. In fact, this series made
no assumption which hardware/display controller will be the user.

I have investigated before respin this patch, there are other hardwares which
ship the it66121 display bridge. For example, the Fresco Logic FL2000dx USB 3.0
to VGA display adapter[1][2]. Even the windows have a driver.

[1] https://github.com/FrescoLogic/FL2000
[2] https://oemdrivers.com/graphics-fresco-logic-fl2000