[Intel-gfx] [RFC] Reduce idle vblank wakeups

[Andrew Lutomirski]

2011/11/16 Matthew Garrett <mjg59 at srcf.ucam.org>:
> On Wed, Nov 16, 2011 at 06:03:15PM +0100, Michel Dänzer wrote:
>
>> I thought the main reason for the delay wasn't broken hardware but to
>> avoid constantly ping-ponging the vblank IRQ between on and off with
>> apps which regularly neeed the vblank counter value, as that could make
>> the counter unreliable. Maybe I'm misremembering though.
>
> If turning it on and off results in the counter value being wrong then
> surely that's a hardware problem? I've tested that turning it on and off
> between every IRQ still gives valid counter values on sandybridge.

This, and the thread that contains it, might be interesting:

http://permalink.gmane.org/gmane.comp.video.dri.devel/53201

In summary: there was some resistance to doing this in January, but I
couldn't find any legitimate reason.

--Andy