On Mon, Aug 29, 2005 at 01:52:14PM -0400, Greg Lee wrote: > > > Currently I've made a preliminary firmware for implementing the > > > CDC-ACM interface, however as Pavel kindly pointed out for me, > > > currently only 64Kbyte/sec is achieveable with this driver. I've read > > > the archives and from the discussions, I suspect that this is > > > connected to the NO_FSBR flag.. > > > > > > Questions which popped out of my mind: > > > 1. Is there some standard way to allow for >64Kbytes/sec using the > > > 2.6.x CDC-ACM driver? (I mean without modification of the sources, but > > > setting some #defines or such) I'd not mind a reasonably slower PCI > > > bus.. > > > > I don't know. I've never heard about a 64 KB/s limitation > > for CDC-ACM. > > This conversation is worrisome, I work with a number of devices that are > accessed through usbserial and ACM (e.g. wireless/cellular modems) that have > data rates in the 1-2 Mbits/s range. There are devices coming out in the > next few months that will be in the 3-6 Mbits/s range with 13 Mbits/s a year > out. > > This discussion of possible underlying data rate limitations in the CDC-ACM > implementation is worrisome. Does anyone have a precise answer for what the > data rate limitations are of these two implementations (usbserial and ACM)?
Both of these drivers by default are not tuned for speed at all. It would only require a small bit of work to crank the data rates up for them, if needed. See some of the usb-serial (not the generic one) drivers for details on how to do this (pools of urbs, creating them on the fly, etc.) Now if someone were to send a developer a device that needed the increased speeds, that would probably get the required kernel changes done faster :) thanks, greg k-h ------------------------------------------------------- SF.Net email is Sponsored by the Better Software Conference & EXPO September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
