On Fri November 16 2012 16:20:03 Sakari Ailus wrote: > Hi Hans, > > Thanks for the comments! > > On Fri, Nov 16, 2012 at 02:51:29PM +0100, Hans Verkuil wrote: > > On Thu November 15 2012 23:06:44 Sakari Ailus wrote: > > > diff --git a/Documentation/DocBook/media/v4l/io.xml b/Documentation/DocBook/media/v4l/io.xml > > > index 7e2f3d7..d598f2c 100644 > > > --- a/Documentation/DocBook/media/v4l/io.xml > > > +++ b/Documentation/DocBook/media/v4l/io.xml > > > @@ -938,6 +938,31 @@ Typically applications shall use this flag for output buffers if the data > > > in this buffer has not been created by the CPU but by some DMA-capable unit, > > > in which case caches have not been used.</entry> > > > </row> > > > + <row> > > > + <entry><constant>V4L2_BUF_FLAG_TIMESTAMP_MASK</constant></entry> > > > + <entry>0xe000</entry> > > > + <entry>Mask for timestamp types below. To test the > > > + timestamp type, mask out bits not belonging to timestamp > > > + type by performing a logical and operation with buffer > > > + flags and timestamp mask.</tt> </entry> > > > + </row> > > > + <row> > > > + <entry><constant>V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN</constant></entry> > > > + <entry>0x0000</entry> > > > + <entry>Unknown timestamp type. This type is used by > > > + drivers before Linux 3.8 and may be either monotonic (see > > > + below) or realtime. Monotonic clock has been favoured in > > > + embedded systems whereas most of the drivers use the > > > + realtime clock.</entry> > > > > Isn't 'wallclock time' a better expression? It is probably a good idea as > > well to add the userspace call that gives the same clock: gettimeofday or > > clock_gettime(CLOCK_REALTIME) for the wallclock time and > > clock_gettime(CLOCK_MONOTONIC) for the monotonic time. That way apps can > > do the same call and compare it to the timestamp received. > > I'll add a reference to clock_gettime() and change realtime to wall clock > time. I wonder if I should also add that the unknown timestamp means either > of the two, or can we allow different kinds of unknown timestamps in the > future. No. UNKNOWN should never be used in the future. It is specific to the pre timestamp flag era where the timestamp is really only one of two options. Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
