What you are querying there is the "device descriptor", it's not a
dynamic variable based current conditions. It's not about the packets
ize talking over the network, it's talking to the control endpoint of
that device (aka endpoint zero).
The vendor of that device configured bMaxPacketSize to a size of 8 to
talk to endpoint zero. This is no more configurable by you, then
changing it's device class, and has nothing to do with USB-R.
FWIW, almost all HID devices (such as a sig pad) have bMaxPacketSize of
8 in the device descriptor.
On 4/25/13 11:19 AM, Karl Rossing wrote:
On 2013-04-25 11:09 AM, Craig Bender wrote:
Tuning like this is done in the application/driver for the device.
FWIW, It's not a dropped packet (USB-R, like other things that need
guaranteed delivery, use TCP), it's a timeout issue. A timeout due to
the latency of your WAN connection.
Many USB devices are coded with strict (over even just the USB
specification default) timing requirements since they assume they'll
be on a local bus. Some devices, such as isochronous devices, require
this strict timing, but most don't.
I would venture to guess that the latency of the WAN connection is >
20ms? That seems to be the magic number of death for USB devices that
have (sometimes needlessly) strict timing requirements.
Correct.
Call the sigpad vendor and see if they have a driver that has more
relaxed or configurable timeouts for use with USB over IP. Tell them
what the latency is for working and non-working scenarios. 20ms is a
lifetime compared to the latency of a local USB bus.
Before I do that, I think there still a problem on the linux side of
things.
If I do a lsusb I get a transfer type of Interrupt with a
"bMaxPacketSize0 8" and "wMaxPacketSize 0x0008 1x 8 bytes"
Am I correct in thinking that the usb packet size should be more than 8
and that may improve the performance of the signature pad?
CONFIDENTIALITY NOTICE: This communication (including all attachments) is
confidential and is intended for the use of the named addressee(s) only and
may contain information that is private, confidential, privileged, and
exempt from disclosure under law. All rights to privilege are expressly
claimed and reserved and are not waived. Any use, dissemination,
distribution, copying or disclosure of this message and any attachments, in
whole or in part, by anyone other than the intended recipient(s) is
strictly
prohibited. If you have received this communication in error, please
notify
the sender immediately, delete this communication from all data storage
devices and destroy all hard copies.
_______________________________________________
SunRay-Users mailing list
[email protected]
http://www.filibeto.org/mailman/listinfo/sunray-users
_______________________________________________
SunRay-Users mailing list
[email protected]
http://www.filibeto.org/mailman/listinfo/sunray-users
