Re: prototype of a USB v4l2 driver? gspca?

[Andrea <audetto@tiscali.it>]

Hans de Goede wrote:
> Andrea wrote:
> 
> What kind of device, I think that for webcams you;re best using gspca, 
> (now merged in mecurial), that handles all the usb specific stuff, 
> buffer management, etc. In general it makes it easy to write a webcam 
> driver allowing you to focus on the interaction with the cam, rather 
> then having to worry about looking, usb specifics, buffer management etc.
> 

I've had a quick look at the structure of gspca, and it seems that any subdriver should just (easier 
to say that to do) fill one of those structures

struct sd_desc {
/* information */
	const char *name;	/* sub-driver name */
/* controls */
	const struct ctrl *ctrls;
	int nctrls;
/* operations */
	cam_cf_op config;	/* called on probe */
	cam_op open;		/* called on open */
	cam_v_op start;		/* called on stream on */
	cam_v_op stopN;		/* called on stream off - main alt */
	cam_v_op stop0;		/* called on stream off - alt 0 */
	cam_v_op close;		/* called on close */
	cam_pkt_op pkt_scan;
/* optional operations */
	cam_v_op dq_callback;	/* called when a frame has been dequeued */
	cam_jpg_op get_jcomp;
	cam_jpg_op set_jcomp;
	cam_qmnu_op querymenu;
};

1) providing ctrls (+ functions to handle settings)
2) functions to open/stream/close etc...

It does not seem too bad.

The a natural question that comes to me:

Shouldn't many more USB drivers be implemented as subdrivers of gspca?
But I guess there is much more I don't know under the apparent easy interface.

Andrea

--
video4linux-list mailing list
Unsubscribe mailto:video4linux-list-request@redhat.com?subject=unsubscribe
https://www.redhat.com/mailman/listinfo/video4linux-list