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

[Daniel Vetter]

On Tue, Sep 03, 2019 at 11:19:19AM +0200, Heinrich Fink wrote:
> 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.

It's the same script, but I think CI uses some different options/flags. I
generally ignore these, but also generally good to stick to the style.

$ dim checkpatch

in our maintainer-tools should give you the drm flavoured checkpatch.
-Daniel

> 
> - 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

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch