On Tue, 2026-01-20 at 13:45 +0200, Jani Nikula wrote: > On Tue, 20 Jan 2026, Daniel Stone <[email protected]> wrote: > > Hi, > > > > On Tue, 20 Jan 2026 at 10:33, Michel Dänzer <[email protected]> > > wrote: > > > On 1/19/26 02:11, Tomasz Pakuła wrote: > > > > [Why] > > > > ALLM automatically puts TVs into low latency modes (gaming modes) which > > > > we basically always want for PC use, be it gaming, or using precise > > > > inputs like mice and keyboards. > > > > > > How about e.g. video playback though? > > > > > > It might make sense to let the Wayland compositor control this, e.g. via > > > the Wayland content type hint protocol. > > > > Yes, I think this should be a connector property. We'll happily > > implement support for Weston as the uAPI vehicle. > > Content type might be a useful policy hint also for content adaptive > brightness control and the like. > > Ville and I have also tossed around ideas for passing the "power mode" > to the DRM drivers (e.g. Performance, Balanced, Power Saver). There are > various cases where the drivers need to make policy decisions that would > be better decided by userspace. However, it gets complicated and > unweildy if all of them are individual knobs. A power mode input might > be useful in making the latency decisions too. > > BR, > Jani.
Hmm, looking at the wp_content_type_v1 enum, I see it was probably based on the CTA-861 Content Type information than can be supplied to the AVI info frame? The values are identical. This surely could be plumbed into drm_connector and basically directly set in the AVI info frame. But, ALLM is something different and overrides the content type info. It should be separate information, probably a simple switch to inform drm_connector if it should be used. I don't know if ALLM setting should always be exposed and let the drivers determine if it can be used, or should it appear dynamically based on EDID though that's a consideration for desktop environments. In this case, ALLM of course would always take precedence and as far as it's activation, it maybe would only be disabled when presenting fullscreen photos/video? Content type notwithstanding. Now, from a perspective of someone that actually uses PCs connected to TVs and dip his toes into more TV topics, there should be a way to force ALLM to be always on, no matter the content. I'd even advocate for it to be the default because a long standing truth is that all the special modes we have in our TVs and Monitors are garbage. They mess up the picture, boost it to high heavens and some mode forcibly turn on motion- smoothing. With a PCs, we always expect the content to already be sent in high quality, and even HTPC users prefer any post-process to be done on the PC itself. Moreover, mode picture mode switching causes jarring transitions and in same cases, toggling game mode can even blank a screen for a moment, though it's rare. We at least got Filmmaker mode as a crux, that often still need little fine tuning, but doesn't make a mess of the picture. Oftentimes TVs will detect PCs and disable most processing outright and content types can have little to no effect. Again, like always with TVs, YMMV. Game mode, sometimes merged with PC mode doesn't suck, and usually gives the picture that's the closest to what the media actually is (be it vide, HDR video, photo) and closest to selected color gamut standards like bt.709, DCI-P3, bt.2020. In many ways, it will provide best picture quality already, but maybe marketing departments wouldn't agree. I can assure you, that as soon as the TV starts changing modes based on the content, and there isn't a way to disable it, people will complain hard. All in all, if there will be a way to obtain all this information and set appropriate info in AVI/HF-VSDB, then I'm sure it will be plumbed through but for now, I think just having ALLM forced is a good idea. Maybe, just maybe a property in sysfs/module setting could be used to disable this if there's a big need. There's another thing though. amdgpu already sets the IT content type bit which already disables most if not all post-processing in sink devices (or at least should). TVs often detect this as "PC" mode. Sometimes ALLM is then needed to expose features like higher refresh rate and VRR, thus the aforementioned mode change to update the exposed EDID. Oh, and ALLM only toggles the game mode if the game mode setting on the TV is actually auto, with other values "off" and "on". It's just nice to not have to manually turn it on. Tomasz
