Hi Brandon, On Friday 12 October 2007, Brandon Philips wrote: > Hello- > > I don't know if I like the idea of needing a udev/hotplug script to map > my camera features.
Alternative ideas are welcome. I thought about ways to solve the extension units controls problem for a while and couldn't come with a better solution. Hardcoding all controls in the drivers is not a long term solution. > However, I reviewed dynctrl.txt it seems reasonable. > > I just had one question: > > __u32 flags See below > > > > * struct uvc_xu_control_info flags field > > > > UVC_CONTROL_SET_CUR Control is writable. > > UVC_CONTROL_GET_CUR Control is readable. > > UVC_CONTROL_GET_MIN Control supports GET MIN queries. > > UVC_CONTROL_GET_MAX Control supports GET MAX queries. > > UVC_CONTROL_GET_RES Control supports GET RES queries. > > UVC_CONTROL_GET_DEF Control supports GET DEF queries. > > UVC_CONTROL_RESTORE Control should be restored when resuming from > > sleep. > > Quoting the UVC spec: > > "All controls supported by the Extension Unit must support the following > requests: GET_CUR, GET_MIN, GET_MAX, GET_RES, GET_INFO, GET_DEF, > GET_LEN" > > And the driver can find out about SET_CUR via GET_INFO. So, besides > RESTORE what is this flag field needed for? GET_MIN, GET_MAX, GET_RES and GET_DEF are used internally. XU controls are handled like other controls, so the driver needs to remember which requests are supported for every control, including the XU controls. UVCIOC_CTRL_ADD sets the GET_MIN, GET_MAX, GET_RES and GET_DEF flags. The current implementation allows applications to add control definitions without a corresponding device plugged in the system. This means the driver won't be able to query the control using GET_INFO at the time it is added, hence the need to set GET_CUR and SET_CUR manually. This is an internal implementation issue and I'll try to get rid of it. > Thanks, > > Brandon > > P.S. Is there a Logitech XU spec sheet somewhere? It would be nice to > have information on the controls on my device. There is no public document. I'll see if I can get them to release their internal spec, or at least part of them. Best regards, Laurent Pinchart _______________________________________________ Linux-uvc-devel mailing list [email protected] https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
