On Wed, May 27, 2015 at 04:17:05PM +0900, Michel Dänzer wrote: > On 26.05.2015 20:48, Daniel Vetter wrote: > > On Tue, May 26, 2015 at 05:53:38PM +0900, Michel Dänzer wrote: > >> From: Michel Dänzer <michel.daenzer@xxxxxxx> > >> > >> dev->max_vblank_count contains the largest value that can be represented > >> by the hardware counter. When the hardware counter wraps around, we have > >> to add that value + 1 to get the same value as if the hardware counter > >> didn't wrap around. > >> > >> Signed-off-by: Michel Dänzer <michel.daenzer@xxxxxxx> > > > > Well there's two users of this really, one wants the max (this one here) > > and the other a mask. > > Well, this one has been around much longer. :) Looks like drm_vblank_on > added a (probably valid, see below) assumption without updating the > field name to reflect that. Yeah, might be clearer to open-code the (slower) divide just for clarity. Anyway applied this patch to drm-misc. > > And all the drivers use it as a mask. > > How so? They just assign the value, which happens to work for both > meanings above in all cases. Yeah I had the usual confusion about where exactly we start counting here ;-) I was thinking of num_vblank_counts_before_wrap vs. mask. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
