Steam Deck OLED

[UnidentifiedTag]

could the steam deck oled have rebar enabled ?

a cmos reset according to the Internet can be done by

hold down the Volume Down button, the Three-dot button, and Power button at the same time

as this doesn’t sound like a hardware kind of cmos reset and the only way to recover from a failed flash would be to pull out a usb programmer and de-solder the bios chip, I’ll probably avoid this It’s always nice to be 1st.

[terminatorul]

dmesg shows ReBAR is enabled with 1 GiB BAR size, but lspci does not show any BAR with 1 GiB size. Can you link the full output from lspci -t -vvv ?

[UnidentifiedTag]

Maybe this is what you was on about when you said 1gb?

there’s no option for resize bar or above 4g decoding

Just this frame buffer thing at 1gb

[UnidentifiedTag]

so are you saying i could try and compile a rebar file for bios file and that would likely work but the v3 auto thing you made wont

[terminatorul]

Oh, UMA ... !

This is a custom GPU chip where the video RAM (vRAM) and system RAM (or DRAM) are the same. Like a very large iGPU.

Yes, I think this is what dmesg output shows.

With unified memory, I don't know if ReBAR is still relevant for the GPU. It does not have the effect it has with a discrete GPU. I guess it can still help, but very likely it is not worth loosing system RAM over the pseuo-BAR size. I don't have such a system and I can not be sure, but I hear for iGPUs it is just better to let the GPU driver use the unified memory directly as a large BAR.

[UnidentifiedTag]

Let’s say I want to go ahead, would you’re 0.3v work or would I need to use the compile option for the module, get my numbers from cpuid like you would with any system and go down it that way. If I do have to compile 0.1v doesn’t support sleep, could you change that? leaving only the need for hard coded numbers?

[terminatorul]

NvStrapsReBar would not work because the Steam Deck has an AMD GPU (so not an NVIDIA Turing GPU).

I never found the documentation with the address for the straps bits for AMD GPUs. And I did not look for it, because for AMD they are not needed to enable ReBAR. AMD GPUs can enable ReBAR with a registry key.

[UnidentifiedTag]

What about ReBarDxe.ffs by @xCuri0

Is that the one that supports all graphics cards, I was under the impression that NvStrapsReBar by yourself @terminatorul supported everything? So that’s maybe something else I need to document that your rebar method only supports Nvidia? Is that right? Bit confused now to be honest?

[xCuri0]

@UnidentifiedTag I don't see Resizable BAR capability so I don't think it would work

I know AMD has BAR straps too but they aren't really documented.

You should check the GPU-Z Vulkan memory thing to see if the driver is actually using 1024mb I'm sure there's a way to do it on Linux