Re: [Linux-uvc-devel] [SVN] Added preliminary pan/tilt support for Quickcam Orbit MP

[Laurent P. <lau...@sk...>]

> The pantilt reset now work fine , but the pan tilt relative, not really
> like i need  :)
> as i did not really understand, how the signed value are in the 4 char
> array, i have try to set up one union like that :
> union pantilt {
> 	struct {
> 		short pan;
> 		short tilt;
> 	} s16;
> 	int value;
> } pantilt;
> so i expect s16.pan reffer to the signed value of pan  and
> s16.tilt to the tilt value.
> as a result the sign of relative goes right, tilt and pan is not mixed and
> i can scan min to max or max to min , but difficukt to stop the scan
> between :(

I just noticed that there's an endianess problem in the driver. Please try the 
following code.

-----------------------------------------------------------------------------
union pantilt {
	unsigned char bytes[4];
	int value;
} pantilt;

pantilt.bytes[0] = (pan >> 0) & 0xff;
pantilt.bytes[1] = (pan >> 8) & 0xff;
pantilt.bytes[2] = (tilt >> 0) & 0xff;
pantilt.bytes[3] = (tilt >> 8) & 0xff;

ctrl.value = pantilt.value;
-----------------------------------------------------------------------------

This will only work on little endian platforms. Please note that the interface 
will probably change as soon as I find time to rework the controls handling 
code.

Laurent Pinchart