Re: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE ioctls

[Ville Syrjälä]

On Thu, Jul 06, 2017 at 09:28:40AM -0700, Keith Packard wrote:
> Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> writes:
> 
> > Maybe, or maybe we want to turn the interrupt on in that case? That's
> > what the old ioctl does.
> 
> That's what I suggested in my reply to Daniel's review. Even if we add
> the accurate function, we'll still need the interrupt-enable case as a
> fallback for drivers which don't support the accurate path, right?

TBH I didn't even consider that case, but yeah makes sense. Otherwise
the counter won't start to tick and the result of the query is pretty
much useless.

I was mostly thinking of the 'seq = query(); wait(seq + n);' pattern
where we can avoid doing the full update more than once if we enable
the interrupt already during the query.

-- 
Ville Syrjälä
Intel OTC