Hi Aurel, sorry for the long delay.
On Thursday 24 January 2008, Aurel Gabris wrote: > Hi Laurent, > > First of all, it seems that I have a problem with my on-board usb 2.0 > controller. Even after upgrading the BIOS to the most recent one, the USB > 2.0 host writes this into the syslog: > usb 4-2: new high speed USB device using ehci_hcd and address 3 > usb 4-2: unable to read config index 0 descriptor/start > usb 4-2: chopping to 0 config(s) > usb 4-2: string descriptor 0 read error: -71 > usb 4-2: string descriptor 0 read error: -71 > usb 4-2: string descriptor 0 read error: -71 > usb 4-2: no configuration chosen from 0 choices > > (the camera is plugged directly into a port on the motherboard, using the > cable that came with the monitor) > > I've spent hours searching the web for a solution, but no success... I > have upgraded to latest kernel, latest BIOS: nothing. Interestingly, it > does seem to work in Windows! Anyway, I just thought I'll mention this, > perhaps you have some ideas... You should really raise this issue on the linux-usb-devel mailing list. There are a few USB gurus there. > On the other hand, I tested the webcam with another machine (where USB 2.0 > worked). I tested both with and without the ehci-hcd module. With USB 2.0 > enabled everything was working fine: > luvcview (0.2.1) > amsn (0.97b) > ekiga (2.0.11) > > When I unloaded ehci-hcd and left the USB only with ohci-hcd, I was > receiving the same errors as I've reported in my last post. So, in > nutshell luvcview and ekiga was basically usable, but amsn mostly died. > > > There's one strange thing you may be interested in: > > With USB 2.0, luvcview can only use the yuv format: jpg dies with "Unable > to set format: 22". > > With USB 1.1, it behaves the contrary: only "-f jpg" works. > > I wonder if this is on purpose. If not, I could send you some trace logs. That's indeed interesting. If you look at the USB descriptors you posted, you will notice that the camera reports different frame formats depending on the USB version. With USB 2.0 (EHCI) it reports uncompressed formats only, and with USB 1.1 (OHCI) it reports compressed formats only. This is completely legal, but it's the first time I see a device that disables MJPEG when used with a USB 2.0 controller (most devices just disable YUV in USB 1.1 mode). > So, in summary you can probably include this webcam on the supported list > (limited support with USB 1.1). Done. Thanks. > I'm going to copy here the full outputs of > 'lsusb -v' both when the EHCI module was loaded, and when I used it with > OHCI. The latter may be interesting for you if you'd like to go into the > yuv<->jpg format issue. Best regards, Laurent Pinchart _______________________________________________ Linux-uvc-devel mailing list Linux-uvc-devel@lists.berlios.de https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
