As the topic described, I didn’t realize five years later we still can’t do 4k120 from HDMI expansion card. I don’t want to be rude but this needs to be a thing yesterday…
At least now we have dp2.1 from intel core ultra 3, it would be easier to do the conversion.
Problem is that HDMI forum hates open source, not sure how framework is affected but I guess they’re not better off than AMD. Just two articles I found by quick googling that describe the problem.
https://www.howtogeek.com/hdmi-forum-open-source-drivers-hdmi-2-1/
https://www.makeuseof.com/hdmi-forum-is-holding-back-linux-and-its-getting-worse/
DP1.4 with DSC can allready do 4k120 HDMI with an active adabter, I have used a 20$ chinesium one with a usb-c to dp adabter onm y 7840u fw13 just fine. They’d just need to stick one of those in an expansion card to cover that though it would likely get a bit cramped in there.
The hdmi forum is cancer but that isn’t the problem here as you’d need an active converter anyway, same way the intel gpus got around the hdmi forum limitation on linux (and probably to avoid having to deal with hdmi in the first place too).
Re: HDMI 2.1 on Linux
Fortunately, this is changing.
Kernel 7.2 includes the first HDMI 2.1 support from AMD, with more in 7.4 on the way to a “full implementation”, pending compliance testing.
Intel HDMI 2.1 “native” FRL is in progress too
I have not heard confirmation of what changed that allowed the open-source 2.1 driver support to be released now, but it has been speculated that the HDMI Forum decided the succeeding 2.2 development and release in June allowed 2.1 to be unfettered. Intentionally being held back a generation would be a disappointing precedent for future versions. Others suggest additional pressure from Valve may have contributed.
Like @Adrian_Joachim noted above though, none of this actually impacts the Framework HDMI expansion card. FW’s laptop mainboards use only the GPU DP output over USB-C DP alt mode. The HDMI cards then use a Parade PS186 PCON to convert to HDMI. We’d probably need someone from Framework to comment on why they haven’t made an HDMI 2.1 version.
All AMD APUs used by Framework support DP 2.1 as well.
The apus do but the redrivers used on at least the 7x40u ones limit it to DP1.4, still enough for 4k120 with an active adabter though.
There’s a stealth release with the Framework 12 of a 4th gen HDMI module that’s 2.1 compliant
yep, just noticed this too: https://frame.work/gb/en/products/hdmi-expansion-card-4th-gen?v=FRACDEBZ04
Well that’s tragic.
From the block diagram on the GH repo, I see the 7040U boards use both the KB8002 (UHBR10, but only DP 1.4) and the ANX7493 (also UHBR10, but DP 2.0). What do each of the retimers do? I guess the output is limited limited by the KB8002?
The AI 300 boards seem to use a PS8835 (DP 2.1) instead of the KB8002? Is this board also not actually capable of DP 2.1?
UHBR10 is only a little faster than UHBR3, the real improvement in DP2 is UHBR20 and the new way it does mst so I am glad they aren’t calling it DP2.
According to this the AI300 ones have some ports capable of DP2 with UHBR20.