On Sun, Oct 28, 2018 at 9:25 AM Akinobu Mita <akinobu.mita@xxxxxxxxx> wrote:
>
> 2018年10月28日(日) 12:49 Matt Ranostay <matt.ranostay@xxxxxxxxxxxx>:
> >
> > On Sat, Oct 20, 2018 at 7:26 AM Akinobu Mita <akinobu.mita@xxxxxxxxx> wrote:
> > >
> > > Add macro to compare two v4l2_fract values in v4l2 common internal API.
> > > The same macro FRACT_CMP() is used by vivid and bcm2835-camera. This just
> > > renames it to V4L2_FRACT_COMPARE in order to avoid namespace collision.
> > >
> > > Cc: Matt Ranostay <matt.ranostay@xxxxxxxxxxxx>
> > > Cc: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > > Cc: Hans Verkuil <hansverk@xxxxxxxxx>
> > > Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
> > > Acked-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > > Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
> > > ---
> > > * v4
> > > - No changes from v3
> > >
> > > include/media/v4l2-common.h | 5 +++++
> > > 1 file changed, 5 insertions(+)
> > >
> > > diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h
> > > index cdc87ec..eafb8a3 100644
> > > --- a/include/media/v4l2-common.h
> > > +++ b/include/media/v4l2-common.h
> > > @@ -384,4 +384,9 @@ int v4l2_g_parm_cap(struct video_device *vdev,
> > > int v4l2_s_parm_cap(struct video_device *vdev,
> > > struct v4l2_subdev *sd, struct v4l2_streamparm *a);
> > >
> > > +/* Compare two v4l2_fract structs */
> > > +#define V4L2_FRACT_COMPARE(a, OP, b) \
> > > + ((u64)(a).numerator * (b).denominator OP \
> > > + (u64)(b).numerator * (a).denominator)
> > > +
> >
> > Noticed a few issues today when testing another thermal camera that
> > can do 0.5 fps to 64 fps with this macro..
>
> I expect your new thermal camera's frame_intervals will be something
> like below.
>
> static const struct v4l2_fract frame_intervals[] = {
> { 1, 64 }, /* 64 fps */
> { 1, 4 }, /* 4 fps */
> { 1, 2 }, /* 2 fps */
> { 2, 1 }, /* 0.5 fps */
> };
>
> > 1) This can have collision easily when numerator and denominators
> > multiplied have the same product, example is 0.5hz and 2hz have the
> > same output as 2
>
> I think V4L2_FRACT_COMPARE() can correctly compare with 0.5hz and 2hz.
>
> V4L2_FRACT_COMPARE({ 1, 2 }, <=, { 2, 1 }); // --> true
> V4L2_FRACT_COMPARE({ 2, 1 }, <=, { 1, 2 }); //--> false
>
> > 2) Also this doesn't reduce fractions so I am seeing 4000000 compared
> > with 4 for instance with a 4hz frame interval.
>
> I think this works fine, too.
>
> V4L2_FRACT_COMPARE({ 1, 4000000 }, <=, { 1, 4 }); //--> true
> V4L2_FRACT_COMPARE({ 1, 4 }, <=, { 1, 4000000 }); //--> false
>
> Or, do I misunderstand your problem?
Probably not! I didn't think of them having to be sorted in a certain
way, but will test and probably will work.
Couldn't hurt to have that noted in a comment some where as well.
- Matt
