linux-kernel - Re: [PATCH v2 1/4] drm/bridge: Add fwnode based helpers to get the next bridge

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Date: Sat, 9 Mar 2024 19:25:36 +0800
From: Sui Jingfeng <sui.jingfeng@...ux.dev>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Andrzej Hajda <andrzej.hajda@...el.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Phong LE <ple@...libre.com>, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/4] drm/bridge: Add fwnode based helpers to get the
 next bridge

Hi,

On 2024/3/9 18:39, Dmitry Baryshkov wrote:
> On Sat, 9 Mar 2024 at 11:33, Sui Jingfeng <sui.jingfeng@...ux.dev> wrote:
>> Hi,
>>
>>
>> On 2024/3/8 04:40, Dmitry Baryshkov wrote:
>>>>> But really, there is nothing so hard about it:
>>>>> - Change of_node to fw_node, apply an automatic patch changing this in
>>>>> bridge drivers.
>>>>> - Make drm_of_bridge functions convert passed of_node and comp
>>>>>
>>>>> After this we can start cleaning up bridge drivers to use fw_node API
>>>>> natively as you did in your patches 2-4.
>>>> Yes, it's not so hard. But I'm a little busy due to other downstream developing
>>>> tasks. Sorry, very sorry!
>>>>
>>>> During the talk with you, I observed that you are very good at fwnode domain.
>>>> Are you willing to help the community to do something? For example, currently
>>>> the modern drm bridge framework is corrupted by legacy implement, is it possible
>>>> for us to migrate them to modern? Instead of rotting there? such as the lontium-lt9611uxc.c
>>>> which create a drm connector manually, not modernized yet and it's DT dependent.
>>>> So, there are a lot things to do.
>>> Actually, lontium-lt9611uxc.c does both of that 😉 It supports
>>> creating a connector and it as well supports attaching to a chain
>>> without creating a connector. Pretty nice, isn't it?
>>
>> But why the drm_bridge_connector helpers and/or the drm_connector bridge can't suit you need?
>> Coding this way just add boilerplate into drm bridge subsystem, right?
> Because there are platforms, like iMX LCDIF which can use the
> lt9611uxc bridge, but do not make use of the drm_bridge_connector yet.
>

Well, I have just grepped across the drm-tip kernel branch, but I don't find
iMX LCDIF you mentioned. See the search results pasted at bellow.

$ find . -name "*.dts" -type f | xargs grep "lontium,lt9611uxc"
/arm64/boot/dts/qcom/sm8450-hdk.dts:		compatible = "lontium,lt9611uxc";
/arm64/boot/dts/qcom/qrb5165-rb5.dts:		compatible = "lontium,lt9611uxc";
/arm64/boot/dts/qcom/qrb2210-rb1.dts:		compatible = "lontium,lt9611uxc";
/arm64/boot/dts/qcom/qrb4210-rb2.dts:		compatible = "lontium,lt9611uxc";
/arm64/boot/dts/qcom/sm8350-hdk.dts:		compatible = "lontium,lt9611uxc";

So I can't see the drm driver that you refer to, can you pointed it out for study
purpose? Even it's exist, however, back to that time, why don't you posting a patch
to switch it to the canonical design as you mentioned and give the community a clean
design?

And those are just *reasons*, from the viewpoint of the *result*.
The merged patch results in a 'side-by-side' implement and boilerplate added
into drm bridges subsystem, the results doesn't change no matter what the
reason is, right?