Hi Harry,
Il giorno lun 7 ago 2023 alle ore 11:02 Harry Waschkeit <
harry.waschk...@conplement.de> ha scritto:
> Hi,
>
> I have a RaspberryPi 4 where on one USB port a Sierra Wireless LTE
> module (EM7455) is attached via an PCIe-to-USB adapter.
> The boot image I use gets built by Yocto with the help of poky
> (kirkstone) and meta-raspberry (beside a few other layers) which
> incorporates U-Boot 22.01.
>
> When I apply power to the board it will come up until scanning USB
> devices (for potential boot devices), but then throw a BUG end reset the
> board.
Do you need USB boot devices? If not, I would build U-Boot without USB
support.
Massimo
> This continues as long as the modem is unplugged.
> The exact error message is:
>
> scanning bus xhci_pci for devices... WARN halted endpoint, queuing URB
> anyway.
> Unexpected XHCI event TRB, skipping... (3af519b0 00000004 13000000
> 02008401)
> BUG at drivers/usb/host/xhci-ring.c:503/abort_td()!
> BUG!
> resetting ...
>
> Some internet research brought up a patch (1) for
> drivers/usb/host/xhci-ring.c where halted devices simply get ignored
> during enumeration:
>
> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> index acf437104a..6d995f446e 100644
> --- a/drivers/usb/host/xhci-ring.c
> +++ b/drivers/usb/host/xhci-ring.c
> @@ -227,7 +227,8 @@ static int prepare_ring(struct xhci_ctrl *ctrl,
> struct xhci_ring *ep_ring,
> puts("WARN waiting for error on ep to be cleared\n");
> return -EINVAL;
> case EP_STATE_HALTED:
> - puts("WARN halted endpoint, queueing URB anyway.\n");
> + puts("WARN halted endpoint.\n");
> + return -EPIPE;
> case EP_STATE_STOPPED:
> case EP_STATE_RUNNING:
> debug("EP STATE RUNNING.\n");
>
> The driver file itself stems from the Linux sources, so I'm pretty sure
> that it is correct in that context.
> Even though I'm not really into USB stuff and therefore I cannot not
> really follow the discussion for the proposed change, in my eyes the
> patch could be reasonable for U-Boot nevertheless given that a) in my
> experience driver code is often used in a simplified way in U-Boot
> compared to Linux kernel, and b) it's all about board start-up only and
> not about full OS use with all bells, whistles and full error handling.
>
> Of course, I might be wrong while missing some important other use or
> corner cases, so I wanted to check here :-)
>
> At least, what I can say: with this patch I see a bunch of these warning
> messages but the board comes up and is usable in the end by Linux.
>
> fwiw: my internet search also showed another patch labelled in the first
> place "[PATCH] pi4: fix crash when issuing usb reset" (2) that didn't
> make it into the particular U-Boot 22.01 but was integrated right after
> that version in commit "Prepare v2022.04" with hash
> e4b6ebd3de982ae7185dbf689a030e73fd06e0d2 (3).
> As I first hoped I could address my problem by just adding this patch I
> got promptly disappointed. The only thing I gained was to now get
> endless error messages followed by retries until I power-cycled the
> board (causing to start all over):
>
> USB XHCI 1.00
> scanning bus xhci_pci for devices... WARN halted endpoint, queueing URB
> anyway.
> Unexpected XHCI event TRB, skipping... (3afd6b30 00000004 13000000
> 02008401)
> XHCI abort timeout
> WARN halted endpoint, queueing URB anyway.
> Unexpected XHCI event TRB, skipping... (3afd6b40 00000004 13000000
> 02008401)
> XHCI abort timeout
> WARN halted endpoint, queueing URB anyway.
> Unexpected XHCI event TRB, skipping... (3afd6b50 00000004 13000000
> 02008401)
> XHCI abort timeout
> WARN halted endpoint, queueing URB anyway.
> [...]
>
> To me it means that this specific PCIe-to-USB bridge might misbehave
> somehow,
> but the final question is: what are the odds to get that patch into
> official U-boot, or any other fix/quirk to make my hardware combo working?
>
> And also interesting: if I cannot hope for an upstream change, what
> potential risks I would have to accept when keeping my patch?
>
> Regards,
> Harry
>
> (1)
>
> https://linux-usb.vger.kernel.narkive.com/VW4VTVDU/patch-usb-host-xhci-fix-halted-endpoint-handling
> (2)
> https://lore.kernel.org/all/3d4ece94-932a-25dd-ef29-0ddfb4a51...@denx.de/T/
> (3)
>
> https://source.denx.de/u-boot/u-boot/-/commit/e4b6ebd3de982ae7185dbf689a030e73fd06e0d2
>
> --
> i.A. Harry Waschkeit
> Senior Embedded Engineer
> conplement AG
> Südwestpark 92
> 90449 Nürnberg
>
> Handelsregister: HRB 22863
> Registergericht: Nürnberg
> Vertreten durch: Britta Waligora und Thomas Wahle
> Vorsitzender des Aufsichtsrates: Lorenz von Schröder
>
>
