On Mon, 2016-03-14 at 13:41 +0100, Lukas Wunner wrote:
<snip>
So I'd push DIGD to the switch sysfs entry on boot. But I'm guessing that won't turn off the other output we're not interested in.
IGD and DIGD switch to the integrated GPU and also turn off the discrete GPU. However if the machine is already switched to the integrated GPU, the commands are no-ops and the discrete GPU is not turned off.
In other words you need to check (by reading the switch file) which GPU the machine is switched to. If it's the integrated GPU, write OFF to the switch file. If it's the discrete GPU, write DIGD to the switch file.
Once runtime pm works, writing DIGD is sufficient.
I tested the runtime patches for Radeon on top of 4.6.0-rc2, and writing DIGD failed. I also saw a number of messages with the vga_switcheroo core in the kernel trying to switch GPUs but failed because "client 1" was keeping it busy.
Is there any way to see what this "client 1" actually is? I'm guessing plymouth. In any case, once I'm logged in, the "DIS" is powered and used, and the IGD is powered as well.
Cheers