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 <mario.kleiner.de@gmail.com> Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
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@ -105,7 +105,7 @@ nouveau_display_scanoutpos_head(struct drm_crtc *crtc, int *vpos, int *hpos,
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if (retry) ndelay(crtc->linedur_ns);
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} while (retry--);
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*hpos = calc(args.hblanks, args.hblanke, args.htotal, args.hline);
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*hpos = args.hline;
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*vpos = calc(args.vblanks, args.vblanke, args.vtotal, args.vline);
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if (stime) *stime = ns_to_ktime(args.time[0]);
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if (etime) *etime = ns_to_ktime(args.time[1]);
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