Comment 54 for bug 1749961

I tried with iommu=off when I last looked at this and the problem
persisted.

On Tue, Jun 23, 2020, 12:25 AM Mikko Rantalainen <email address hidden>
wrote:

> Could somebody that is seeing this problem try to boot with kernel flag
> "iommu=off". Some hardware that used to work with older kernels may be
> broken and fails to work with modern kernels which default to using
> IOMMU.
>
> Note that disabling IOMMU is a heavy handed workaround, not a proper
> fix. For more information about IOMMU, see https://heiko-sieger.info
> /iommu-groups-what-you-need-to-consider/
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1749961
>
> Title:
> xhci_hcd: TRB DMA errors reported with ASMedia ASM1142 USB 3.1
> Controller
>
> Status in linux package in Ubuntu:
> In Progress
> Status in linux source package in Trusty:
> Won't Fix
> Status in linux source package in Xenial:
> In Progress
> Status in linux source package in Bionic:
> In Progress
> Status in linux source package in Focal:
> Confirmed
> Status in linux package in Debian:
> Confirmed
>
> Bug description:
> It was observed that while trying to use a 4K USB webcam connected to
> USB port provided by ASMedia ASM1142 USB 3.1 Controller, the webcam
> does not work and kernel log shows the following messages:
>
> [431.928016] xhci_hcd 0000:12:00.0: ERROR Transfer event TRB DMA ptr not
> part of current TD ep_index 2 comp_code 13
> [431.928021] xhci_hcd 0000:12:00.0: Looking for event-dma
> 0000003f3330e020 trb-start 0000003f3330e000 trb-end 0000003f3330e000
> seg-start 0000003f3330e000 seg-end 0000003f3330eff0
> [431.928024] xhci_hcd 0000:12:00.0: ERROR Transfer event TRB DMA ptr not
> part of current TD ep_index 2 comp_code 13
> [431.928026] xhci_hcd 0000:12:00.0: Looking for event-dma
> 0000003f3330e030 trb-start 0000003f3330e000 trb-end 0000003f3330e000
> seg-start 0000003f3330e000 seg-end 0000003f3330eff0
> [431.928027] xhci_hcd 0000:12:00.0: ERROR Transfer event TRB DMA ptr not
> part of current TD ep_index 2 comp_code 13
> [431.928029] xhci_hcd 0000:12:00.0: Looking for event-dma
> 0000003f3330e050 trb-start 0000003f3330e000 trb-end 0000003f3330e000
> seg-start 0000003f3330e000 seg-end 0000003f3330eff0
> [431.928386] xhci_hcd 0000:12:00.0: ERROR Transfer event TRB DMA ptr not
> part of current TD ep_index 2 comp_code 13
>
> A similar issue was already reported on Launchpad:
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1667750
>
> The fix to this issue seems to be the following patch:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9da5a109
>
> Tests in our scenario with this patch proved still broken. Our next
> approach is to modify the patch a bit and re-test.
>
> This LP will be used to document our progress in the investigation.
>
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>