On Fri, 25 Sep 2009, Joris van Rantwijk wrote: > Hi, > > When reading data from a high speed device with usbserial.ko, I sometimes > get corruct data. > > For example, the device sends a bulk packet of 73 bytes. > The host receives 73 bytes of which the first 69 are good but the last > 4 bytes are wrong. It looks very much like those last 4 bytes are old > content still in the URB buffer from a previous packet. This happens > about once per 1000 transfers. > > This problem does not occur when I use cdc-acm instead of usbserial. > But cdc-acm uses coherent DMA mappings (whatever that means) unlike > usbserial. > > Has anyone seen this before? > Is this a DMA problem in my EHCI controller? Have you tried using your device on a different computer with a different sort of motherboard? If the problem still occurs then most likely it's in the device, not in the computer hardware. 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
