On Wed, May 23, 2018 at 06:41:35PM +0100, Marc Zyngier wrote: > Back around the 4.13 timeframe, we tried to address a rather bad issue > with the Renesas uPD72020x USB3 controller family. They have trouble > with the programming of the base addresses which tend to stick on XHCI > reset. This makes transitionning from 64bit to 32bit addresses > completely unsafe. This was observed on a fairly popular arm64 > platform (AMD Opteron 1100, which has all of its memory above 4GB). > > The fix was to perform a PCI reset of the device, but we have had > multiple reports that this generated regressions (the controller not > being usable after the patch was applied). > > This series reverts the problematic patch, and tries to address it in > a more constrained way. If the controller is behind an IOMMU (and only > in that case), we zero its base addresses before reseting it. In the > affected configuration, this has the effect of putting the device in a > state where the XHCI reset will be effective. > > It must be noted that in the absence of an IOMMU (and maybe even in > its presence), this device is completely unsafe, and may silently > corrupt memory. Mathias, any objections for me queueing these up now for 4.18-rc1? thanks, greg k-h -- 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
