Thanks again Alex! Some comments inlined below:
On 09/12/2021 15:06, Alex Deucher wrote:
Not really in a generic way. It's asic and platform specific. In addition most modern displays require link training to bring up the display, so you can't just save and restore registers.
Oh sure, I understand that. My question is more like: is there a way, inside amdgpu driver, to save this state before taking over/overwriting/reprogramming the device? So we could (again, from inside the amdgpu driver) dump this pre-saved state in the shutdown handler, for example, having the device in a "pre-OS" state when the new kexec'ed kernel starts.
The drivers are asic and platform specific. E.g., the driver for vangogh is different from renoir is different from skylake, etc. The display programming interfaces are asic specific.
Cool, that makes sense! But if you (or anybody here) know some of these GOP drivers, e.g. for the qemu/qxl device, I'm just curious to see/understand how complex is the FW driver to just put the device/screen in a usable state.
Cheers,
Guilherme