[PATCH v2] drm: Add high-precision time to vblank trace event

[Heinrich Fink]

On Tue, 3 Sep 2019 at 09:46, Daniel Vetter <daniel at ffwll.ch> wrote:
>
> On Mon, Sep 02, 2019 at 04:24:12PM +0200, Heinrich Fink wrote:
> > Store the timestamp of the current vblank in the new field 'time' of the
> > vblank trace event. If the timestamp is calculated by a driver that
> > supports high-precision vblank timing, set the field 'high-prec' to
> > 'true'.
> >
> > User space can now access actual hardware vblank times via the tracing
> > infrastructure. Tracing applications (such as GPUVis, see [0] for
> > related discussion), can use the newly added information to conduct a
> > more accurate analysis of display timing.
> >
> > v2 Fix author name (missing last name)
> >
> > [0] https://github.com/mikesart/gpuvis/issues/30
> >
> > Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> > Signed-off-by: Heinrich Fink <heinrich.fink at daqri.com>
>
> Applied, thanks.

thanks! One question: After sending v2, I got an email from patchwork
pointing at some failed style checks (CHECK:PARENTHESIS_ALIGNMENT,
CHECK:COMPARISON_TO_NULL). Just so I know for the future, are these
checks mandatory to be addressed? I haven't had a chance to address
them yet. FWIW, linux-tree/scripts/checkpatch.pl did not complain.

- Heinrich

> -Daniel
>
> > ---
> >  drivers/gpu/drm/drm_trace.h  | 14 ++++++++++----
> >  drivers/gpu/drm/drm_vblank.c |  3 ++-
> >  2 files changed, 12 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_trace.h b/drivers/gpu/drm/drm_trace.h
> > index 471eb927474b..11c6dd577e8e 100644
> > --- a/drivers/gpu/drm/drm_trace.h
> > +++ b/drivers/gpu/drm/drm_trace.h
> > @@ -13,17 +13,23 @@ struct drm_file;
> >  #define TRACE_INCLUDE_FILE drm_trace
> >
> >  TRACE_EVENT(drm_vblank_event,
> > -         TP_PROTO(int crtc, unsigned int seq),
> > -         TP_ARGS(crtc, seq),
> > +         TP_PROTO(int crtc, unsigned int seq, ktime_t time, bool high_prec),
> > +         TP_ARGS(crtc, seq, time, high_prec),
> >           TP_STRUCT__entry(
> >                   __field(int, crtc)
> >                   __field(unsigned int, seq)
> > +                 __field(ktime_t, time)
> > +                 __field(bool, high_prec)
> >                   ),
> >           TP_fast_assign(
> >                   __entry->crtc = crtc;
> >                   __entry->seq = seq;
> > -                 ),
> > -         TP_printk("crtc=%d, seq=%u", __entry->crtc, __entry->seq)
> > +                 __entry->time = time;
> > +                 __entry->high_prec = high_prec;
> > +                     ),
> > +         TP_printk("crtc=%d, seq=%u, time=%lld, high-prec=%s",
> > +                     __entry->crtc, __entry->seq, __entry->time,
> > +                     __entry->high_prec ? "true" : "false")
> >  );
> >
> >  TRACE_EVENT(drm_vblank_event_queued,
> > diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
> > index fd1fbc77871f..c99feda25dea 100644
> > --- a/drivers/gpu/drm/drm_vblank.c
> > +++ b/drivers/gpu/drm/drm_vblank.c
> > @@ -1731,7 +1731,8 @@ static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe)
> >               send_vblank_event(dev, e, seq, now);
> >       }
> >
> > -     trace_drm_vblank_event(pipe, seq);
> > +     trace_drm_vblank_event(pipe, seq, now,
> > +                     dev->driver->get_vblank_timestamp != NULL);
> >  }
> >
> >  /**
> > --
> > 2.23.0.rc1
> >
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch