Comment 318 for bug 752542

On the Dell Vostro 3550, for which info is already attached, the ACPI call \_SB.PCI0.PEG0.PEGP._OFF successfully disables the onboard radeon card, or at least claims to and reduces power use dramatically.

After this acpi call is made, there's about a 10 second delay during resume from sleep as the radeon driver hunts around for the card. It looks like the intel video bios doesn't like the card disappearing either, complaining:

[ 238.692874] [drm:atom_op_jump] *ERROR* atombios stuck in loop for more than 5secs aborting
[ 238.692878] [drm:atom_execute_table_locked] *ERROR* atombios stuck executing CCB4 (len 62, WS 0, PS 0) @ 0xCCD0
[ 238.692881] [drm:atom_execute_table_locked] *ERROR* atombios stuck executing B9C8 (len 1036, WS 4, PS 0) @ 0xBAC5
[ 238.692884] [drm:atom_execute_table_locked] *ERROR* atombios stuck executing B95E (len 76, WS 0, PS 8) @ 0xB966

then repeatedly

[ 244.058077] [drm:atom_op_jump] *ERROR* atombios stuck in loop for more than 5secs aborting
[ 244.058080] [drm:atom_execute_table_locked] *ERROR* atombios stuck executing CCB4 (len 62, WS 0, PS 0) @ 0xCCD0

.... so be careful when turning off secondary video hardware.