UAPI Re: [PATCH 1/3] drm: Add DRM_MODE_TV_MODE_MONOCHROME

[Maxime Ripard]

Hi Pekka,

On Wed, Feb 21, 2024 at 11:07:51AM +0200, Pekka Paalanen wrote:
> On Fri, 16 Feb 2024 18:48:55 +0000
> Dave Stevenson <dave.stevenson at raspberrypi.com> wrote:
> 
> > From: Nick Hollinghurst <nick.hollinghurst at raspberrypi.com>
> > 
> > Add this as a value for enum_drm_connector_tv_mode, represented
> > by the string "Mono", to generate video with no colour encoding
> > or bursts. Define it to have no pedestal (since only NTSC-M calls
> > for a pedestal).
> > 
> > Change default mode creation to acommodate the new tv_mode value
> > which comprises both 525-line and 625-line formats.
> > 
> > Signed-off-by: Nick Hollinghurst <nick.hollinghurst at raspberrypi.com>
> > Signed-off-by: Dave Stevenson <dave.stevenson at raspberrypi.com>
>
> since no-one else commented yet, I'd like to remind of the new UAPI
> requirements:
> https://dri.freedesktop.org/docs/drm/gpu/drm-uapi.html#open-source-userspace-requirements
> 
> AFAIU, adding a new value to an existing enum still counts as new UAPI.
> 
> Maybe there is no need for the full treatment here, or maybe there is,
> I'm not sure. I think you should make some statement about how the new
> UAPI requirements have been addressed.

That property was meant to provide legacy display handling, so I don't
expect any reasonably recent codebase like Weston to suppport it, ever
:)

That being said, from the beginning, that property was meant to be
handled as a "mode-setting" property, and thus handled by either the
kernel command-line, xrandr, or any similar mechanism.

I would expect that new enum variant to be handled under the same terms:
it'll probably only show up in distro scripts or configuration files,
and never in any actual code base.

Is it what you were expecting, or did you mean something else?

Maxime
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