Created attachment 122654 [details]
dmesg using tentative fix

Alexandre, using the tentative fix you uploaded it switches GPUs properly now.
Here is the dmesg from that since there are still some errors related to power
state in it. Also, for some reason lshw is returning this for the nVidia GPU
now:

*-generic
                description: Unassigned class
                product: Illegal Vendor ID
                vendor: Illegal Vendor ID
                physical id: 0
                bus info: pci@0000:01:00.0
                version: ff
                width: 32 bits
                clock: 66MHz
                capabilities: bus_master vga_palette cap_list rom
                configuration: driver=nouveau latency=255 maxlatency=255
mingnt=255
                resources: irq:129 memory:dc000000-dcffffff
memory:b0000000-bfffffff memory:c0000000-c1ffffff ioport:e000(size=128)
memory:dd000000-dd07ffff

I don't know if that's related to this at all but before, if I set runpm=0 and
run lshw, it would return the proper description (running it without runpm
would cause the system to hang)