writing custom driver for VGA emulation ?

[Alex Deucher]

On Tue, Feb 18, 2020 at 2:56 AM Yusuf Altıparmak
<yusufalti1997 at gmail.com> wrote:
>
> Hello AMD team;
>
> I have E 9171 GPU and want to use it on a embedded system which has limited MMIO space on PCIe bus (MAX 512 MB).
>
> I received feedbacks that I can only use VGA emulation with this memory space. I was unable to get 'amdgpu' driver working with Xorg due to I had many errors(firmwares are not loading) in each step and tired of solving them one by one.
>
> I want to write a simple custom driver for this GPU with kernel version 4.19.
> Is it possible to print some colors on screen with a custom driver over PCIe communication ? or writing some words on screen as VGA ?
>
> If answer is yes, then which code pieces (on amdgpu driver folder) or reference documentation should I use? I have Register Reference Guide.pdf.
>
> I will be appreciated for your guidance.

That is not going to do what you want on your platform.  The VGA
emulation requires that you set up the card first to enable it, which
in turn requires MMIO access and thus you are back to square one.

Alex