[Arm-netbook] Monitor support

Stefan Monnier monnier at iro.umontreal.ca
Tue Dec 27 19:59:35 GMT 2016

> I wonder, does EOMA68-A20 support these commands, especially without
> proprietary firmware for it's Mali GPU?

This has nothing to do with MALI: a GPU is a (co)processor which lets
you do computations often useful for graphics (but nowadays also used
for other things), so it is usually wired such that it can write
directly onto the framebuffer memory.

But the GPU itself sees the framebuffer as some chunk of memory, writes
to it, and that's it.  It has nothing to do with bringing this chunk of
memory to an LCD or some other display, which is instead done by some
other circuitry (called the "display engine" (DE) on the A20).
The same goes for the video-decode accelerator (aka VPU), which
is usually also a completely independent piece of hardware, BTW, which
also just writes to the framebuffer.

In the x86 world, since the graphics cards include both the GPU, the
VPU, and the "display engine", those notions are usually conflated,
but technically, they are independent, and in the ARM world they tend to
be clearly separate.

So, the question in your case is if the DE can handle your timings and
if the `xrandr` thingy will be able to properly configure the hardware.
AFAIK the A20's hardware should have no trouble with a 1600x1200x85Hz
timing, so the question is more on the software side.

For the "vanilla" kernels, I know there's some "sunxi-drm" module
available (tho AFAIK it still hasn't been merged into Linus's tree), so
some of the infrastructure is available but you still need an Xorg server
on top (presumably the `modesetting` driver might do the trick).


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