gpu/vga_switcheroo: add driver control power feature. (v3)

Hello, Dave!

I have a hybrid muxless laptop with intel+radeon:
#lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09) 01:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Cape Verde [Radeon HD 7700M Series]

I have some questions related to this series of patches.
When I power down discrete card by vgaswitcheroo, restart X server and turn on radeon card again, xrandr doesn't recognize my discrete card and only shows the intel one. Is this a bug or a feature of X server? And how would this behavior change with this patch?

Also sometimes I have the following configuration:

# cat /sys/kernel/debug/vgaswitcheroo/switch
0:DIS: :Pwr:0000:01:00.0
1:IGD:+:Pwr:0000:00:02.0

In this case if I do

# echo OFF > /sys/kernel/debug/vgaswitcheroo/switch
the system hangs and doesn't respond (ssh, magic keys etc.).

In the meantime for a

# cat /sys/kernel/debug/vgaswitcheroo/switch
0:IGD:+:Pwr:0000:00:02.0
1:DIS: :Pwr:0000:01:00.0

# echo OFF > /sys/kernel/debug/vgaswitcheroo/switch
powers down discrete card successfully.

Would it be resolved with these patches?

Hohahiu

PS. Should I open bug report for these issues?

Yes this with radeon support will save you having to power down things yourself, so would just make it all happen dynamically and you'd never see it.

However if the machine dies on power down that could be fun to solve with these patches as well.

Dave.