On Thu, 17 Sep 2009, Hunter, Jon wrote: > Hi All, > > I have been working on a USB problem that appears to be resolved by the following patch (commit a2c2706e1043c17139c2dafd171c4a5cf008ef7e) > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a2c2706e1043c17139c2dafd171c4a5cf008ef7e > > The changelog for this patch reads: > > USB: EHCI: add software retry for transaction errors > > This patch (as1204) adds a software retry mechanism to ehci-hcd. It > gets invoked when the driver encounters transaction errors on an > asynchronous endpoint. On many systems, hardware deficiencies cause > such errors to occur if one device is unplugged while the host is > communicating with another device. With the patch, the failed > transactions are retried and generally succeed the second or third > time through. > > This description "on many systems, hardware deficiencies cause such errors to occur if one device is unplugged while the host is communicating with another device" describes the problem to a tee. Such that I see a usb failure when one device busy and another is connected. > > The above mentions that "hardware deficiencies" can cause this. I am curious to know if anyone has more details on these hardware deficiencies and if there are any chipsets that are known to be problematic. All I can tell you is that several Intel chipsets are known to hav this problem. > I have seen this problem on my ubuntu laptop which has an intel usb host controller. No surprise there. 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
