On Thu, 12 Feb 2004, Guennadi Liakhovetski wrote:

> Hello, Alan
> 
> And thanks for rememberring about this problem. Have you got any
> additional information about the VIA specifics?

A contact at VIA says that this particular error occurs only in USB 
controllers with revision number < 5.  I think your experience proves that 
he is wrong.

> Short:
> 00:07.2 USB Controller: VIA Technologies, Inc. UHCI USB (rev 16)
> 00:07.3 USB Controller: VIA Technologies, Inc. UHCI USB (rev 16)
> 
> Long (-vv) attached at the end (don't think it's needed, just in case).
> The EHCI card in the other PC has revision 50 and, as reported before, has
> the same problem.

Unless your camera is a high-speed device, when you plug it into an EHCI 
controller it will be automatically handed off to the companion full-speed 
controller -- which is probably also a VIA UHCI.

At the moment, the only way we have for preventing these problems is to
not allow them to happen in the first place.  That means making certain
that all reads from a USB device request a multiple of the maximum packet
size, even if the amount of data expected is smaller.  That way a babble 
error is impossible unless the USB device is _really_ broken.

If you feel up to it, you could try editing the gphoto2 source.  Find the
part that handles the file listing transfers, and round the transfer
length up to the next multiple of the maxpacket size (probably 64 but
check in /proc/bus/usb/devices).

Alan Stern



-------------------------------------------------------
SF.Net is sponsored by: Speed Start Your Linux Apps Now.
Build and deploy apps & Web services for Linux with
a free DVD software kit from IBM. Click Now!
http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click
_______________________________________________
[EMAIL PROTECTED]
To unsubscribe, use the last form field at:
https://lists.sourceforge.net/lists/listinfo/linux-usb-devel

Reply via email to