Re: [PATCH] omap3isp: Use monotonic timestamps for statistics buffers

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sakari,

On Friday 14 September 2012 00:01:39 Sakari Ailus wrote:
> On Thu, Sep 13, 2012 at 09:53:23PM +0200, Laurent Pinchart wrote:
> > V4L2 buffers use the monotonic clock, while statistics buffers use wall
> > time. This makes it difficult to correlate video frames and statistics.
> > 
> > Switch statistics buffers to the monotonic clock to fix this.
> > 
> > Reported-by: Antoine Reversat <a.reversat@gmail.com>
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > ---
> > 
> >  drivers/media/platform/omap3isp/ispstat.c |    6 +++++-
> >  1 files changed, 5 insertions(+), 1 deletions(-)
> > 
> > diff --git a/drivers/media/platform/omap3isp/ispstat.c
> > b/drivers/media/platform/omap3isp/ispstat.c index b8640be..52263cc 100644
> > --- a/drivers/media/platform/omap3isp/ispstat.c
> > +++ b/drivers/media/platform/omap3isp/ispstat.c
> > @@ -253,10 +253,14 @@ isp_stat_buf_find_oldest_or_empty(struct ispstat
> > *stat)> 
> >  static int isp_stat_buf_queue(struct ispstat *stat)
> >  {
> > +	struct timespec ts;
> > +
> >  	if (!stat->active_buf)
> >  		return STAT_NO_BUF;
> > 
> > -	do_gettimeofday(&stat->active_buf->ts);
> > +	ktime_get_ts(&ts);
> > +	stat->active_buf->ts.tv_sec = ts.tv_sec;
> > +	stat->active_buf->ts.tv_usec = ts.tv_nsec / NSEC_PER_USEC;
> > 
> >  	stat->active_buf->buf_size = stat->buf_size;
> >  	if (isp_stat_buf_check_magic(stat, stat->active_buf)) {
> 
> I didn't think wall clock timestamps were used for statistics. This change
> is sure going to affect anyone using them --- which likely equates to no-one
> since I can hardly see use for wall clock timestams in such use.
> 
> How about using struct timespec instead?

Sounds good. I've tested it on ARM, x86-32 and x86-64, and both structures 
have the same size. I'll send a v2.

-- 
Regards,

Laurent Pinchart