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

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Message-ID: <50006160-f82b-4ec1-91a4-2ebbd7752e1d@linux.dev>
Date:   Thu, 16 Nov 2023 18:29:39 +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 2023/11/15 00:30, Dmitry Baryshkov wrote:
>> @@ -703,14 +704,32 @@ static int it66121_bridge_attach(struct drm_bridge *bridge,
>>                                   enum drm_bridge_attach_flags flags)
>>   {
>>          struct it66121_ctx *ctx = bridge_to_it66121(bridge);
>> +       struct drm_bridge *next_bridge = ctx->next_bridge;
>> +       struct drm_encoder *encoder = bridge->encoder;
>>          int ret;
>>
>> -       if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR))
>> -               return -EINVAL;
>> +       if (next_bridge) {
>> +               if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)) {
>> +                       WARN_ON(1);
> Why? At least use WARN() instead

If (next_bridge) is true, it says that the driver *already* known that
it66121 have a next bridges attached. Then it66121 driver should certainly
attach it, no matter what it is. Either a connector or another display bridge.
It also says that this is a DT-based system on such a case. CallingWARN_ON(1) here helps to see(print) which DC driver is doing the wired 
things. Ok, I will remove the WARN_ON(1)  on the next version.