Re: [PATCH 3/3] usb: xhci: Unify duplicate inc_enq() code

[Mathias Nyman]

On 24.2.2025 23.01, Michał Pecio wrote:
> On Mon, 24 Feb 2025 13:49:29 +0200, Mathias Nyman wrote:
> > Interesting, I wonder if setting the link TRB chain bit would
> > also help with the TRB prefetch issue on VIA VL805 hosts.
>
> Good idea, but unfortunately not.
>
> With xhci_hcd quirks=1, which is XHCI_LINK_TRB_QUIRK:
>
> [    0.543465] pci 0000:0a:00.0: [1106:3483] type 00 class 0x0c0330 PCIe Endpoint
>
> [  406.745905] xhci_hcd 0000:0a:00.0: xHCI Host Controller
> [  406.745916] xhci_hcd 0000:0a:00.0: new USB bus registered, assigned bus number 11
> [  406.747265] xhci_hcd 0000:0a:00.0: hcc params 0x002841eb hci version 0x100 quirks 0x0000000000000891
>
> [  407.475672] usb 11-1.4: Found UVC 1.00 device USB2.0 Camera (1e4e:0103)
>
> [  407.697768] usb 11-1.4: Selecting alternate setting 12 (3060 B/frame bandwidth)
> [  407.700432] usb 11-1.4: Allocated 5 URB buffers of 32x3060 bytes each
> [  407.732047] xhci_hcd 0000:0a:00.0: AMD-Vi: Event logged [IO_PAGE_FAULT domain=0x0005 address=0xffccc000 flags=0x0000]
> [  407.732122] xhci_hcd 0000:0a:00.0: WARNING: Host System Error
> [  407.732133] xhci_hcd 0000:0a:00.0: AMD-Vi: Event logged [IO_PAGE_FAULT domain=0x0005 address=0xffccc000 flags=0x0000]
> [  407.732151] xhci_hcd 0000:0a:00.0: AMD-Vi: Event logged [IO_PAGE_FAULT domain=0x0005 address=0xffccc000 flags=0x0000]
>
> Link TRBs from debugfs:
>
>   0 0x00000000ffccbff0: LINK 00000000ffcca000 intr 0 type 'Link' flags i:C:t:C
>   1 0x00000000ffccaff0: LINK 00000000ffccb000 intr 0 type 'Link' flags i:C:T:c

It was worth a shot,
thanks for trying it out

I'll send the original fix to Greg

-Mathias