[RFC 4/4] drm: add support for raw monotonic vblank timestamps

Michel Dänzer michel at daenzer.net
Fri Oct 5 06:55:11 PDT 2012

On Fre, 2012-10-05 at 16:37 +0300, Imre Deak wrote: 
> In practice we never want the timestamps for vblank and page flip events
> to be affected by time adjustments, so in addition to the gettimeofday
> timestamps we used so far add support for raw monotonic timestamps.
> For backward compatibility use flags to select between the old and new
> timestamp format.
> Note that with this change we will save the timestamp in both formats,
> for cases where multiple clients are expecting an event notification in
> different time formats.

I wonder if all this trouble is really necessary. I honestly can't
imagine any user of this API requiring non-monotonic timestamps and
breaking with monotonic ones. I think it was simply a mistake that we
didn't make them monotonic in the first place (or maybe it wasn't even
possible when this API was first introduced).

Earthling Michel Dänzer           |                   http://www.amd.com
Libre software enthusiast         |          Debian, X and DRI developer

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