EDID solutions for resolutions above 5K

[violetInCorner]

Hi! I need to get a resolution that is above 5K and has a good compatibility for iPhone、iPad、Android、laptop with Integrated graphics、laptop with discrete graphics card.

Test method：My monitor is using a Lontium chip. I can write an EDID with 256 bytes in the chip. And i can read the video timing data from the chip, and judge
the compatibility by checking if the timing data is consistent with the EDID i wrote before.

Now i have the following problems:
(1) Is my test method correct ?
(2) I use the CRU to generate a correct 5K resolution as image. But sometime it didn't work. Here is my test condition:

(A)Alienware taptop M15R4, NVIDIA GeForce RTX 3070, win11, Thunderbolt3

(B)Huawei taptop MetaBook D14, ryzen 4700u, win10, HDMI,

©iPad pro 2021, Apple M1, Thunderbolt3

when in A case, it works, but it will firstly use EDID's resolution, and i need go to the NVIDIA control panel to set the 5K resolution. If here any method to set the 5K resolution as default?
when in B case, it didn't work at all. I use the AMD software: Adrenalin Edition to
create the corresponding resolution, it won't work well. I suspect that win10 has the limit with EDID which has a DisplayID 2.0 extension.
when in C case, it also didn't work. My classmate suspects it's arm firmware chip's question. But i am really not familiar with Arm chips.

Thanks!

[ToastyX]

A) You can delete all the other resolutions. Then it will only use the 5120x1620 resolution.

B) HDMI needs an HDMI data block in a CTA-861 extension block, which should be the first extension block, but then you won't have room for the DisplayID extension block with only 256 bytes. You'll need 384 bytes for two extension blocks. The max TMDS clock in the HDMI data block should also be enabled and set to 340 MHz. If the monitor has DisplayPort and the laptop has a USB-C port that can support a display, you can use a USB-C to DisplayPort cable instead of HDMI. Windows 10 shouldn't be a problem.

C) I don't know how iPad handles external displays. DisplayID 1.3 might work better. The chip shouldn't matter. The graphics driver handles the displays.