On Tue, 19 Mar 2013, Ben Hutchings wrote: > On Mon, 2013-03-18 at 04:22 +0000, Ben Hutchings wrote: > > 3.2-stable review patch. If anyone has any objections, please let me know. > > > > ------------------ > > > > From: Alan Stern <st...@rowland.harvard.edu> > > > > commit feca7746d5d9e84b105a613b7f3b6ad00d327372 upstream. > > > > This patch (as1661) fixes a rather obscure bug in ehci-hcd. In a > > couple of places, the driver compares the DMA address stored in a QH's > > overlay region with the address of a particular qTD, in order to see > > whether that qTD is the one currently being processed by the hardware. > > (If it is then the status in the QH's overlay region is more > > up-to-date than the status in the qTD, and if it isn't then the > > overlay's value needs to be adjusted when the QH is added back to the > > active schedule.) > > > > However, DMA address in the overlay region isn't always valid. It > > sometimes will contain a stale value, which may happen by coincidence > > to be equal to a qTD's DMA address. Instead of checking the DMA > > address, we should check whether the overlay region is active and > > valid. The patch tests the ACTIVE bit in the overlay, and clears this > > bit when the overlay becomes invalid (which happens when the > > currently-executing URB is unlinked). > > > > This is the second part of a fix for the regression reported at: > > > > https://bugs.launchpad.net/bugs/1088733 > > Alan, the first part (commit 6402c796d3b4 aka as1660) didn't apply and I > couldn't see how to adapt it for 3.2. Does this second part have any > value without the first? Or, if you could provide a backport of the > first part, that would be very much appreciated.
Without the first part, the second part can actually be dangerous. Under the circumstances, I think it is best to apply neither. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
