Re: [Qce-ga-discussion] Problem using qce-ga or qc-usb with 2 cams

[Tuukka T. <tu...@ee...>]

On Sun, 15 Feb 2004, vincent Morin wrote:

>quickcam: probe of HDCS1000 sensor = 08 00 id: 08
>quickcam: HDCS1000 sensor detected
>USB Quickcam Class ff SubClass ff idVendor 46d idProduct 840
>USB Quickcam camera found using: $Id: quickcam.c,v 1.102 2002/03/25 22:22:34
>jfclere Exp $
>quickcam: probe of HDCS1000 sensor = 08 00 id: 08
>quickcam: HDCS1000 sensor detected

I'd be happier to see qc-usb logs since I understand it better. However, I
think I can guess what's the problem.

USB bus has 12 Mbit/s limit and you can run only one camera with one bus.
Motherboards with two USB connectors typically have both connected to the
same bus.

Motherboards with four connectors likely have two busses, so you could
then run two cameras. It works here.

You could obtain more busses by buying PCI-based USB interface cards.

>hub.c: already running port 2 disabled by hub (EMI?), re-enabling...

I heard that this could mean "power overload". Maybe some of the cameras
are using more power than is available on the USB bus. For example, I had a
system that worked fine with two simple Quickcam Expressed but whenever I
tried to run Quickcam Web (which probably takes more power) I couldn't get
any other camera to work simultaneously even on different USB bus.

>quickcam: HDCS1000 sensor detected

Also qce-ga has a bug which makes two cameras, one with HDCS-1020 and one
with HDCS-1000 sensor not to work. But this doesn't seem to be your case,
and it's fixed in qc-usb.

>     May I operate correctly the quickcam driver with several cams, in what
>conditions

Yes, if they don't take too much power and if they are in separate USB
busses.