On 09/10/2017 17:22, Mathias Nyman wrote: > On 08.10.2017 17:03, Hao Wei Tee wrote: >> Hi, >> >> I've been having DMA read faults with my VL805 xHCI controller when the Intel IOMMU >> is turned on: >> >> xhci_hcd 0000:03:00.0: xHCI Host Controller >> xhci_hcd 0000:03:00.0: new USB bus registered, assigned bus number 2 >> DMAR: DRHD: handling fault status reg 3 >> DMAR: [DMA Read] Request device [03:00.0] fault addr de28a000 [fault reason 01] Present bit in root entry is clear >> <snip many identical DMAR faults> >> xhci_hcd 0000:03:00.0: can't setup: -110 >> xhci_hcd 0000:03:00.0: USB bus 2 deregistered >> xhci_hcd 0000:03:00.0: init 0000:03:00.0 fail, -110 >> xhci_hcd: probe of 0000:03:00.0 failed with error -110 >> >> The controller works fine, as far as I can tell, when the IOMMU is off. >> >> I've tracked it down to where CMD_RESET is sent to the controller in xhci_reset, >> [1] called from xhci_gen_setup in xhci.c. It seems that when the command register >> is being polled in the xhci_handshake after that, the controller tries to do a >> DMA read from an address that is apparently invalid (?). Eventually xhci_handshake >> times out. >> >> I've tried setting the XHCI_NO_64BIT_SUPPORT quirks flag as someone suggested in >> an earlier thread here [2] about a similar/the same(?) device, but that doesn't >> seem to have worked. >> >> Help, please. I have no idea how to debug this further. >> > > Could it maybe be related to a iommu/vt-d: Fix scatterlist offset handling fix: > https://lists.linuxfoundation.org/pipermail/iommu/2017-September/024371.html > > Can you check if that patch is included? I applied that patch on top of current stable (v4.13.5) and mainline (v4.14-rc4) but it doesn't appear to have changed anything. Hmm. Further searching shows that this probably isn't an IOMMU bug but rather some quirk of the controller itself, probably (?). This bug on Red Hat's bugtracker shows AMD IOMMU faults with the VL805 too. [1]: https://bugzilla.redhat.com/show_bug.cgi?id=1409098 > The author Robin Murphy (CC) Also had some recent issues with a VIA VL805 controller > > https://marc.info/?l=linux-usb&m=150730678304383&w=2 Yeah, that looks like the same thing.. Robin, any luck with your VL805 card? Thanks. > -Mathias -- Hao Wei -- 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
