On Thu, Aug 04, 2016 at 04:11:55PM +0200, Hans Verkuil wrote: > > > On 08/04/2016 04:03 PM, Sakari Ailus wrote: > > Hi Hans, > > > > On Mon, Aug 01, 2016 at 12:33:39PM +0200, Hans Verkuil wrote: > >> Checking the selection constraint flags is often forgotten by drivers, especially > >> if the selection code just clamps the rectangle to the minimum and maximum allowed > >> rectangles. > >> > >> This patch adds a simple helper function that checks the adjusted rectangle against > >> the constraint flags and either returns -ERANGE if it doesn't fit, or fills in the > >> new rectangle and returns 0. > >> > >> It also adds a small helper function to v4l2-rect.h to check if one rectangle fits > >> inside another. > > > > I could have misunderstood the purpose of the patch but... these flags are > > used by drivers in guidance in adjusting the rectangle in case there are > > hardware limitations, to make it larger or smaller than requested if the > > request can't be fulfillsed as such. The intent is *not* to return an error > > back to the user. In this respect it works quite like e.g. S_FMT does in > > cases an exact requested format can't be supported. > > > > <URL:https://www.linuxtv.org/downloads/v4l-dvb-apis/apb.html#v4l2-selection-flags> > > > > What can be done is rather driver specific. > > > > That's not what the spec says: > > https://hverkuil.home.xs4all.nl/spec/uapi/v4l/vidioc-g-selection.html > > ERANGE > It is not possible to adjust struct v4l2_rect r rectangle to satisfy all constraints given in the flags argument. > > It's rather unambiguous, I think. > > If you don't want an error, then just leave 'flags' to 0. That makes sense. Does it? I can't imagine a use case for that. The common section still defines these flags differently, and that's the behaviour on V4L2 sub-device interface. Do we have a driver that implements support for these flags as you described? -- Sakari Ailus e-mail: sakari.ailus@xxxxxx XMPP: sailus@xxxxxxxxxxxxxx -- 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
