On Mon, 9 Dec 2024 at 15:05, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > > Hi, > > On 14-Nov-24 8:10 PM, Ricardo Ribalda wrote: > > Compound controls cannot e reliable clamped. There is plenty of space > > for interpretation for the device manufacturer. > > > > When we write a compound control, let the camera do the clamping and > > return back to the user the value used by the device. > > > > Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> > > --- > > drivers/media/usb/uvc/uvc_ctrl.c | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c > > index 0dae5e8c3ca0..72ed7dc9cfc1 100644 > > --- a/drivers/media/usb/uvc/uvc_ctrl.c > > +++ b/drivers/media/usb/uvc/uvc_ctrl.c > > @@ -2339,6 +2339,18 @@ int uvc_ctrl_set(struct uvc_fh *handle, struct v4l2_ext_control *xctrl) > > > > ctrl->dirty = 1; > > ctrl->modified = 1; > > + > > + /* > > + * Compound controls cannot reliable clamp the value when they are > > + * written to the device. Let the device do the clamping and read back > > + * the value that the device is using. We do not need to return an > > + * error if this fails. > > + */ > > + if (uvc_ctrl_mapping_is_compound(mapping) && > > + uvc_ctrl_is_readable(V4L2_CTRL_WHICH_CUR_VAL, ctrl, mapping)) > > + uvc_mapping_get_xctrl_compound(chain, ctrl, mapping, > > + V4L2_CTRL_WHICH_CUR_VAL, xctrl); > > + > > I do not believe that this actually works / does what you want it to do. > > At this point we have only updated in memory structures for the control > and not send anything to camera. > > Querying the control to return the actual achieved values to userspace > only makes sense after uvc_ctrl_commit() has succeeded, unless I am > missing something ? You are absolutely correct. Sorry about that. Let's drop it for now. Thanks! > > Regards, > > Hans > > -- Ricardo Ribalda
