The drm core currently waits 5 seconds from userspace dropping a request for vblanks to vblanks actually being disabled. This appears to be a workaround for broken hardware, but results in a mostly idle desktop generating a huge number of wakeups that are entirely unnecessary but which consume measurable amounts of power. This patchset makes the vblank timeout per-device rather than global, making it easy for drivers to override the behaviour without compromising other graphics hardware in the system. It then removes the delay on Intel hardware. I've tested this successfully on Sandybridge without any evidence of spurious or missing irqs, but I don't know how well it works on older hardware. Feedback not only welcome, but positively desired.
