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Message-ID: <50006160-f82b-4ec1-91a4-2ebbd7752e1d@linux.dev>
Date:   Thu, 16 Nov 2023 18:29:39 +0800
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Subject: Re: [PATCH 8/8] drm/bridge: it66121: Allow link this driver as a lib
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To:     Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc:     Phong LE <ple@baylibre.com>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        Maxime Ripard <mripard@kernel.org>,
        Sui Jingfeng <suijingfeng@loongson.cn>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Thomas Zimmermann <tzimmermann@suse.de>
References: <20231114150130.497915-1-sui.jingfeng@linux.dev>
 <20231114150130.497915-9-sui.jingfeng@linux.dev>
 <CAA8EJprQq3aDhzE+yKGZ2-nsuHWcptzMvApsyOi9D63PgeiZ3w@mail.gmail.com>
From:   Sui Jingfeng <sui.jingfeng@linux.dev>
In-Reply-To: <CAA8EJprQq3aDhzE+yKGZ2-nsuHWcptzMvApsyOi9D63PgeiZ3w@mail.gmail.com>
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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.