Re: [PATCH v4 1/3] drm/uapi: Add USB connector type

From: Thomas Zimmermann <tzimmermann@suse.de>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: hudson@trmm.net, markus@raatikainen.cc,
	Sam Ravnborg <sam@ravnborg.org>,
	USB list <linux-usb@vger.kernel.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	Tyler Hardin <th020394@gmail.com>,
	Lubomir Rintel <lkundrak@v3.sk>,
	pontus.fuchs@gmail.com, peter@stuge.se
Subject: Re: [PATCH v4 1/3] drm/uapi: Add USB connector type
Date: Thu, 21 Jan 2021 11:01:11 +0100	[thread overview]
Message-ID: <1ea4e6e4-0806-dba1-a424-47f178dc882f@suse.de> (raw)
In-Reply-To: <CAKMK7uHiQ3i-Rz_y_3joR2Zi3fA=1qp8MdGZ9w9PUcGoWT3urw@mail.gmail.com>

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Hi

Am 21.01.21 um 09:27 schrieb Daniel Vetter:
> On Thu, Jan 21, 2021 at 8:45 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>>
>> Hi Noralf,
>>
>> glad to hear from you! Welcome back!
>>
>> Am 20.01.21 um 18:42 schrieb Daniel Vetter:
>>> On Wed, Jan 20, 2021 at 6:10 PM Noralf Trønnes <noralf@tronnes.org> wrote:
>>>>
>>>> Add a connector type for USB connected display panels.
>>>>
>>>> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
>>>> ---
>>>>    include/uapi/drm/drm_mode.h | 1 +
>>>>    1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
>>>> index fed66a03c7ae..33024cc5d26e 100644
>>>> --- a/include/uapi/drm/drm_mode.h
>>>> +++ b/include/uapi/drm/drm_mode.h
>>>> @@ -367,6 +367,7 @@ enum drm_mode_subconnector {
>>>>    #define DRM_MODE_CONNECTOR_DPI         17
>>>>    #define DRM_MODE_CONNECTOR_WRITEBACK   18
>>>>    #define DRM_MODE_CONNECTOR_SPI         19
>>>> +#define DRM_MODE_CONNECTOR_USB         20
>>
>> I would not call it USB. I could imagine that at some point a generic
>> USB protocol could serve simple displays (i.e. in the sense of USB HID
>> or data or imaging). (Maybe Thunderbold already counts.) Anyway, USB
>> should be reserved for this case.
> 
> We end up calling those DisplayPort, since that's what's being
> transported over thunderbolt or usb-C. So the usb connector would be
> called usb-C. I think the reason we don't do fancy connector names is
> that adding them is a bit a pain. Plus drm/i915 specifically has some
> very quirky connector enumerating that doesn't match much with reality
> unfortunately anyway :-/

In the case of the other USB drivers, IIRC we use the connector type 
that is at the output (i.e., HDMI in the case of udl). I think we should 
do the same here. Or use 'Unknown'.

Best regards
Thomas

> -Daniel
> 
>>
>> Best regards
>> Thomas
>>
>>>
>>> Beware, new connector types have in the past resulted in userspace
>>> burning&crashing. Maybe it's become better ...
>>>
>>> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>>>>
>>>>    /**
>>>>     * struct drm_mode_get_connector - Get connector metadata.
>>>> --
>>>> 2.23.0
>>>>
>>>> _______________________________________________
>>>> dri-devel mailing list
>>>> dri-devel@lists.freedesktop.org
>>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>>
>>>
>>>
>>
>> --
>> Thomas Zimmermann
>> Graphics Driver Developer
>> SUSE Software Solutions Germany GmbH
>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>> (HRB 36809, AG Nürnberg)
>> Geschäftsführer: Felix Imendörffer
>>
> 
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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