On Fri, 20 Nov 2009, Stephan Diestelhorst wrote: > Am Dienstag, 17. November 2009 16:04:14 schrieb Oliver Neukum: > > Am Dienstag, 17. November 2009 12:11:39 schrieb Stephan Diestelhorst: > > > Alan Stern wrote: > > > > On Wed, 11 Nov 2009, Stephan Diestelhorst wrote: > > > > > > > This issue is with the built-in Bison web cam in an MSI Wind > > > > > > > U100. Once the camera is enabled (via hotkey), the entire USB > > > > > > > subsystem is not responding anymore, causing non-detection of > > > > > > > freshly attached USB devices and prevents suspending the box. > > > > > > > > > Several volunteers and me have experimented with the udelay values. > > > See > > > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/435352/comments/167 > > > > > > It seems that a delay of 400 usec fixes the thing, and that we're > > > nowhere near the requested 50 usecs. > > > > > > Seems like someone either adds the udelay(400) or introduces a proper > > > fix (with timers). I am too inexperienced in USB things to fully > > > understand the negative implications of the former or do the latter. > > > > as this affects only buggy chipsets, I'd prefer to just add the required > > udelay conditional on a chipset quirk. Do you concur? Do you want me > > to do it and close this bug? > > Thanks for looking into this Oliver! Have you had any chance to work > on this, yet? Ditto. It's kind of surprising to see such a blatant bug in an Intel chipset. Is the 82801G family used in anything other than these netbooks? Do the same problems occur? Alan Stern P.S.: Sarah, is Intel aware of this problem? Is there somebody we should report it to? Basically, the EHCI controller on these computers has a bug: If you enable the periodic schedule and then try to disable it too quickly thereafter (i.e., less than 400 us but after the PSS bit in the status register has turned on), it remains enabled. -- 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
