Hi Guennadi,

On Tuesday 30 August 2011 10:55:08 Guennadi Liakhovetski wrote:
> On Mon, 29 Aug 2011, Laurent Pinchart wrote:
> > On Monday 29 August 2011 14:34:53 Guennadi Liakhovetski wrote:
> > > On Mon, 29 Aug 2011, Laurent Pinchart wrote:
> > > > On Monday 29 August 2011 14:18:50 Guennadi Liakhovetski wrote:
> > > > > On Sun, 28 Aug 2011, Laurent Pinchart wrote:
> > > > > 
> > > > > [snip]
> > > > > 
> > > > > > > @@ -774,17 +839,27 @@ static int ov5642_s_fmt(struct
> > > > > > > v4l2_subdev *sd,
> > > > > > > 
> > > > > > >   ov5642_try_fmt(sd, mf);
> > > > > > > 
> > > > > > > + priv->out_size.width            = mf->width;
> > > > > > > + priv->out_size.height           = mf->height;
> > > > > > 
> > > > > > It looks like to me (but I may be wrong) that you achieve
> > > > > > different resolutions using cropping, not scaling. If that's
> > > > > > correct you should implement s_crop support and refuse changing
> > > > > > the resolution through s_fmt.
> > > > > 
> > > > > As the patch explains (I think) on several occasions, currently
> > > > > only the 1:1 scale is supported, and it was our deliberate choice
> > > > > to implement this using the scaling API
> > > > 
> > > > If you implement cropping, you should use the crop API, not the
> > > > scaling API
> > > > 
> > > > :-)
> > > 
> > > It's changing both - input and output sizes.
> > 
> > Sure, but it's still cropping.
> 
> Why? Isn't it a matter of the PoV?

No it isn't. Cropping is cropping, regardless of how you look at it.

> It changes the output window, i.e., implements S_FMT. And S_FMT is by far
> more important / widely used than S_CROP. Refusing to change the output
> window and always just returning the == crop size wouldn't be polite, IMHO.

If your sensor has no scaler the output size is equal to the crop rectangle. 
There's no way around that, and there's no reason to have the driver behave 
otherwise.

> Don't think many users would guess to use S_CROP.

Users who want to crop use S_CROP.

> Standard applications a la mplayer don't use S_CROP at all.

That's because they don't want to crop. mplayer expects the driver to perform 
scaling when it calls S_FMT, and users won't be happy if you crop instead.

-- 
Regards,

Laurent Pinchart
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