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

Andrew Lutomirski luto at mit.edu
Wed Nov 16 09:53:00 PST 2011

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:


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


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