[igt-dev] [PATCH i-g-t 2/5] tests/kms_setmode: Request the initial vbl count with RELATIVE instead of ABSOLUTE

[Chris Wilson]

Quoting Ville Syrjala (2019-03-07 21:39:23)
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Asking for the initial vblank count by specifying and absolute vblank count of 0
> doesn't make much sense. Switch to a relative query instead.
> 
> It doesn't look like we care about lining up on the first vblank boundary so
> we can just drop the NEXTONMISS flag. Only the relative timestamps of the
> events will matter.
> 
> v2: Drop the NEXTONMISS (Daniel)

No, this isn't about getting the current vblank, it's about aligning the
test to the start of the next vblank period, so that is much less of a
chance of that vblank happening during the setup. For which NEXTONMISS
is essential. You could look at the timestamp and say if within 1ms of
the next vblank, defer? Wasting 8ms is a nuisance but a pittance
compared to the ~2s runtime.
-Chris