I've got an x86 tablet (Dere D10). It works fine, except the screen reports portait resolutions (1200x1920, 768x1024, 600x800, etc.) which causes bootloaders (windows recovery menu, grub, ventoy, etc.) to be in portait-left. Linux behaves similarly: during early boot (efifb driver, i suppose) it's in portait-left, then it switches to portait-right (when it switches to i915, probably).

Ofc I can rotate the screen in tty and the desktop environment but that's not a solution. I can't rotate bootloaders (I sometimes edit text in them, so I need them to display normally) and some applications (e.g. ncurses), and also this causes the touchscreen to be inverted in X and Y, thus unusable.

So, I disassembled the device. The lcd driver bord is small and doesn't seem to have any rom chips on it. It connects directly to the motherboard with a wide thin flat flex cable. So, I assume everything, incl. edid is in the bios rom on the motherboard. This is the only chip that looks like a rom chip.

So I took a dump of the bios. I have a hex editor but I don't understand anything in these byte sections, not to mention the bytes themselves. Maybe someone can explain it to me? Or maybe there is resources that I can start with?


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