On 03/18/2013 03:06 PM, Greg Kroah-Hartman wrote: > 3.8-stable review patch. If anyone has any objections, please let me know. This patch causes reboot/shutdown to fail on Tegra-based systems in 3.9-rc3. I reported this at: http://www.spinics.net/lists/linux-usb/msg82518.html although there's been no discussion there yet, and I haven't had time to investigate exactly what the problem is. > ------------------ > > From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> > > commit 6402c796d3b4205d3d7296157956c5100a05d7d6 upstream. > > This patch (as1660) works around a hardware problem present in some > (if not all) Intel EHCI controllers. After a QH has been unlinked > from the async schedule and the corresponding IAA interrupt has > occurred, the controller is not supposed access the QH and its qTDs. > There certainly shouldn't be any more DMA writes to those structures. > Nevertheless, Intel's controllers have been observed to perform a > final writeback to the QH's overlay region and to the most recent qTD. > For more information and a test program to determine whether this > problem is present in a particular controller, see > > http://marc.info/?l=linux-usb&m=135492071812265&w=2 > http://marc.info/?l=linux-usb&m=136182570800963&w=2 > > This patch works around the problem by always waiting for two IAA > cycles when unlinking an async QH. The extra IAA delay gives the > controller time to perform its final writeback. > > Surprisingly enough, the effects of this silicon bug have gone > undetected until quite recently. More through luck than anything > else, it hasn't caused any apparent problems. However, it does > interact badly with the path that follows this one, so it needs to be > addressed. > > This is the first part of a fix for the regression reported at: > > https://bugs.launchpad.net/bugs/1088733 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html