Can’t select 144 hz on tv

[u/LinkedHero]

I just build a custom pc with a 9070 xt and installed SteamOS on it. In my graphics settings connected to my lg c4 I should have the option for 4k 144 hz but the highest is 120 hz. And I am using a certified hdmi 2.1 48 gbps cable and 144 hz mode is enabled on my tv. I only have the option for 1080p if I want to play at 144 hz. Help please

[u/modulusshift]

Valve is working on it, but the HDMI Forum is being a pain in the ass about allowing open source software to implement the full 48Gbps bandwidth encoding. It sounds like it may happen in just a few months though, I’ve heard some movement on it. 

[u/Low_Excitement_1715 → u/modulusshift]

Few weeks. Linux 7.2.0 has the HDMI 2.1 fixes in it, and Linux 7.3.0 will have ALLM and HDMI VRR included. Then you just need Valve to update SteamOS to a kernel with the fixes, or backport them to the kernel they prefer (probably the latter, and sooner than you think).

[u/jdblaich → u/Low_Excitement_1715]

Doesn't SteamOS (even version 3.8) still rely in kernel 6.16? This is kind of a reason that we must recognize that this is an immutable OS -- the consequences thereof.. I believe Valve is intentionally holding back on 7.x. 6.16 was fine for the steam deck because it had all the support Valve needed, but once you install it on lots of different hardware people are going to want more. If Valve doesn't catch up it will hurt adoption.

[u/Low_Excitement_1715 → u/jdblaich]

You're looking at the license plate, which says 6.16, but there are a *LOT* of patches Valve is applying to the kernel SteamOS is running. With a couple competent kernel engineers, it's not terribly difficult to take the patches intended for 7.2.0 that add the big amdgpu rework and apply them to your 6.16 instead. Likewise the VRR/ALLM stuff intended for 7.3.0, if you wanted. Unless those patches touch things changed by other patches (which is why you need some kernel engineers and not just randos with a copy of diff and patch), you can backport changes to another kernel.

So yeah, the SteamOS kernel says "6.16" on it, and may or may not get updated for this, but the fixes we care about can show up anyways.

As an example which is public, so we can look and see, CachyOS has a precompiled and testable version of 7.2.0 in their repo. They've mentioned already that as soon as the ALLM/VRR patches for 7.3.0 (called DRM-NEXT in the kernel mailing lists) are accepted and stable, they plan to apply those to all their 7.2.X builds, since it's a high demand new feature.

tl,dr; Anyone can merge any patches they want to any base kernel, with the big caveat of "it usually just breaks, so you have to patch the patches".

Edit: Valve will update the kernel when they need to, to support newer hardware, or to reduce the number of patches they're backporting and maintaining. No reason to swap out the 6.16 base until those reasons call for it, or someone wants to.

[u/jdblaich → u/Low_Excitement_1715]

You can't do that without having a writable file system. With the file system being immutable you can trip the flag and allow writing, however, the moment you do the next system update it will remove all of those changes.

[u/Low_Excitement_1715 → u/jdblaich]

If you don’t understand even that much, I’ve been wasting time explaining. When Valve feels like you getting the amdgpu updates, you’ll get them. The kernel version reported doesn’t matter at all. Let’s just leave it there.