On Sat, 7 Aug 2010, Dave Mielke wrote: > One of our (brltty) users is reporting a problem which has begun to occur with > his braille display. It turns out that the problem is actually with how Linux > is interacting with the USB to serial adapter which he's using. dmesg reports > that Linux is using its ftdi_sio driver. > > The problem is that the ftdi_sio driver's data toggle and the ftdi_sio > adapter's data toggle are now at risk of starting out (opening of ttyUSB0) out > of sync. I'm sure this is the problem because it's seemingly random, and, when > it occurs, it corrects after a few data transfer attempts. As you'll see below, > this is a new problem which the ftdi_sio driver didn't used to have. He's > using a Debian system, so my references to kernel releases are what that > distribution calls them. > > His ftdi_sio adapter worked fine up until, and including, kernel 2.6.32-3-686. > Then, when he upgraded to kernel 2.6.32-5-686-18, the problem started to occur. > It still occurs on Debian Unstable's kernel 2.6.32-5-686-19, and it even still > occurs on Debian Experimental's kernel 2.6.35-rc6-686, so I suspect this is a > problem which hasn't been addressed yet. It would help to see a usbmon trace showing the problem, preferably from a 2.6.35 kernel. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
