linux-kernel - Re: [PATCH 1/4] drm: Add I2C connector type

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Message-ID: <a6f267ea-7617-7d0e-06cd-7ec9c88576c3@tronnes.org>
Date:   Tue, 1 Feb 2022 14:20:10 +0100
From:   Noralf Trønnes <noralf@...nnes.org>
To:     Javier Martinez Canillas <javierm@...hat.com>,
        Sam Ravnborg <sam@...nborg.org>
Cc:     linux-fbdev@...r.kernel.org, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Emil Velikov <emil.l.velikov@...il.com>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Maxime Ripard <maxime@...no.tech>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH 1/4] drm: Add I2C connector type



Den 01.02.2022 14.06, skrev Javier Martinez Canillas:
> Hello Noralf,
> 
> On 2/1/22 13:58, Noralf Trønnes wrote:
>>
>>
>> Den 31.01.2022 21.52, skrev Sam Ravnborg:
>>> On Mon, Jan 31, 2022 at 09:12:21PM +0100, Javier Martinez Canillas wrote:
>>>> There isn't a connector type for display controllers accesed through I2C,
>>>> most drivers use DRM_MODE_CONNECTOR_Unknown or DRM_MODE_CONNECTOR_VIRTUAL.
>>>>
>>>> Add an I2C connector type to match the actual connector.
>>>>
>>>> As Noralf Trønnes mentions in commit fc06bf1d76d6 ("drm: Add SPI connector
>>>> type"), user-space should be able to cope with a connector type that does
>>>> not yet understand.
>>>>
>>
>> It turned out that I wasn't entirely correct here, mpv didn't cope with
>> unknown types. In the PR to add support Emil Velikov wondered if libdrm
>> should handle these connector names:
>> https://github.com/mpv-player/mpv/pull/8989#issuecomment-879187711
>>
> 
> I see, thanks for the information. What should we do then, just use the type
> DRM_MODE_CONNECTOR_Unknown then ?
> 

Not really, I just wanted to point out that it could be that not all
userspace will handle an unknown connector type (I just checked the DE's
at the time). I haven't seen any issues after adding the SPI type so it
can't be that many apps that has problems. Adding to that a tiny
monochrome display is limited in which applications it will encounter I
guess :) It was after adding the USB type that I discovered that mpv
didn't work.

Noralf.