Den 29.07.2022 18.34, skrev Maxime Ripard: > Hi, > > Here's a series aiming at improving the command line named modes support, > and more importantly how we deal with all the analog TV variants. > > The named modes support were initially introduced to allow to specify the > analog TV mode to be used. > > However, this was causing multiple issues: > > * The mode name parsed on the command line was passed directly to the > driver, which had to figure out which mode it was suppose to match; > > * Figuring that out wasn't really easy, since the video= argument or what > the userspace might not even have a name in the first place, but > instead could have passed a mode with the same timings; > > * The fallback to matching on the timings was mostly working as long as > we were supporting one 525 lines (most likely NSTC) and one 625 lines > (PAL), but couldn't differentiate between two modes with the same > timings (NTSC vs PAL-M vs NSTC-J for example); > > * There was also some overlap with the tv mode property registered by > drm_mode_create_tv_properties(), but named modes weren't interacting > with that property at all. > > * Even though that property was generic, its possible values were > specific to each drivers, which made some generic support difficult. > > Thus, I chose to tackle in multiple steps: > > * A new TV norm property was introduced, with generic values, each driver > reporting through a bitmask what standard it supports to the userspace; > > * This option was added to the command line parsing code to be able to > specify it on the kernel command line, and new atomic_check and reset > helpers were created to integrate properly into atomic KMS; > > * The named mode parsing code is now creating a proper display mode for > the given named mode, and the TV standard will thus be part of the > connector state; > > * Two drivers were converted and tested for now (vc4 and sun4i), with > some backward compatibility code to translate the old TV mode to the > new TV mode; > > Unit tests were created along the way. Nouveau, ch7006 and gud are > currently broken for now since I expect that work to be reworked fairly > significantly. I'm also not entirely sure about how to migrate GUD to the > new property. > I have looked at gud and I think the future proof solution is to add a new TV_NORM property to the GUD protocol and add backwards compatibility for the GUD_TV_MODE property (just for the modes that Raspberry Pi supports since the gadget driver is out of tree). I don't bother supporting the tv.mode property in userspace (I haven't seen anything that uses the property). I have written up most of the host driver changes but I have to do the gadget side as well to make sure it works. I'll post some patches when I'm done. In hindsight I should have used a bitmask for the TV standards in the first place ;) Noralf.
