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

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Hi

Am 21.01.21 um 09:27 schrieb Daniel Vetter:
> On Thu, Jan 21, 2021 at 8:45 AM Thomas Zimmermann <tzimmermann@xxxxxxx> 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@xxxxxxxxxxx> wrote:
> > > > Add a connector type for USB connected display panels.
> > > >
> > > > Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx>
> > > > ---
> > > >    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@xxxxxxxx>
> > > >    /**
> > > >     * struct drm_mode_get_connector - Get connector metadata.
> > > > --
> > > > 2.23.0
> > > >
> > > > _______________________________________________
> > > > dri-devel mailing list
> > > > dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > > > 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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