Re: [PATCH v7 15/23] drm/modes: Introduce more named modes

[Mateusz Kwiatkowski <kfyatek@gmail.com>]

Hi Noralf,

W dniu 8.11.2022 o 10:38, Noralf Trønnes pisze:
>
> Den 07.11.2022 19.03, skrev Noralf Trønnes:
>>
>> Den 07.11.2022 15.16, skrev Maxime Ripard:
>>> Now that we can easily extend the named modes list, let's add a few more
>>> analog TV modes that were used in the wild, and some unit tests to make
>>> sure it works as intended.
>>>
>>> Signed-off-by: Maxime Ripard <maxime@cerno.tech>
>>>
>>> ---
>>> Changes in v6:
>>> - Renamed the tests to follow DRM test naming convention
>>>
>>> Changes in v5:
>>> - Switched to KUNIT_ASSERT_NOT_NULL
>>> ---
>>>  drivers/gpu/drm/drm_modes.c                     |  2 +
>>>  drivers/gpu/drm/tests/drm_client_modeset_test.c | 54 +++++++++++++++++++++++++
>>>  2 files changed, 56 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
>>> index 49441cabdd9d..17c5b6108103 100644
>>> --- a/drivers/gpu/drm/drm_modes.c
>>> +++ b/drivers/gpu/drm/drm_modes.c
>>> @@ -2272,7 +2272,9 @@ struct drm_named_mode {
>>>  
>>>  static const struct drm_named_mode drm_named_modes[] = {
>>>  	NAMED_MODE("NTSC", 13500, 720, 480, DRM_MODE_FLAG_INTERLACE, DRM_MODE_TV_MODE_NTSC),
>>> +	NAMED_MODE("NTSC-J", 13500, 720, 480, DRM_MODE_FLAG_INTERLACE, DRM_MODE_TV_MODE_NTSC_J),
>>>  	NAMED_MODE("PAL", 13500, 720, 576, DRM_MODE_FLAG_INTERLACE, DRM_MODE_TV_MODE_PAL),
>>> +	NAMED_MODE("PAL-M", 13500, 720, 480, DRM_MODE_FLAG_INTERLACE, DRM_MODE_TV_MODE_PAL_M),
>>>  };
>> I'm now having second thoughts about the tv_mode commandline option. Can
>> we just add all the variants to this table and drop the tv_mode option?
>> IMO this will be more user friendly and less confusing.
>>
> One downside of this is that it's not possible to force connector status
> when using named modes, but I think it would be better to have a force
> option than a tv_mode option. A lot of userspace treats unknown status
> as disconnected.
>
> Anyone know if it's possible to set the connector status sysfs file
> using a udev rule?
>
> Noralf.

I think that leaving named modes only would be a bit limiting. There are use
cases for custom modes, e.g. we might want progressive 240p "NTSC" (like 80s/90s
home computers and video game consoles) or the modes with non-13.5MHz pixel
clock that Geert requested with Amiga in mind.

I'm not sure if the current cmdline-to-drm_mode conversion is flexible enough
to meaningfully facilitate those, but we're at least getting the syntax down.

Best regards,
Mateusz Kwiatkowski