From 6c3252bc83155ae69d78fefdc7458aa64d8a87db Mon Sep 17 00:00:00 2001 From: Mario Kleiner Date: Wed, 19 Mar 2014 10:02:11 +0100 Subject: [PATCH] drm/nouveau: fix small thinko in vblank timestamping. *hpos horizontal scanout position doesn't need to be corrected to count the pixels between hactive end and htotal negative. That is only needed for *vpos to count lines until end of vblank for the vblank timestamping. Use hpos as is without correction. Removes occassional spikes in timestamps of up to 1 scanline duration, thereby improves accuracy to about +/- 2 usecs instead of +/- 12 usecs, wrt. true onset time as measured with high precision equipment on NV-A5. Signed-off-by: Mario Kleiner Signed-off-by: Ben Skeggs --- drivers/gpu/drm/nouveau/nouveau_display.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c index db19a56459f7..b1547b032150 100644 --- a/drivers/gpu/drm/nouveau/nouveau_display.c +++ b/drivers/gpu/drm/nouveau/nouveau_display.c @@ -105,7 +105,7 @@ nouveau_display_scanoutpos_head(struct drm_crtc *crtc, int *vpos, int *hpos, if (retry) ndelay(crtc->linedur_ns); } while (retry--); - *hpos = calc(args.hblanks, args.hblanke, args.htotal, args.hline); + *hpos = args.hline; *vpos = calc(args.vblanks, args.vblanke, args.vtotal, args.vline); if (stime) *stime = ns_to_ktime(args.time[0]); if (etime) *etime = ns_to_ktime(args.time[1]); -- GitLab