[PATCH] usb: xhci: fix event trb handling missed

[Bin Meng]

Hi Ran,

On Tue, Nov 10, 2020 at 1:30 PM Bin Meng <bmeng.cn at gmail.com> wrote:
>
> Hi Ran,
>
> On Tue, Sep 22, 2020 at 1:02 PM Ran Wang <ran.wang_1 at nxp.com> wrote:
> >
> > In functiion xhci_bulk_tx(), when buffer cross 64KB boundary, it will
>
> typo: function
>
> > send request in more than 1 Transfer TRB by chaining them, but then handle
> > only 1 event TRB to mark request completed.
> >
> > However, on Layerscape platforms (LS1028A, LS1088A, etc), we observe xhci
> > controller will generated more than 1 event TRB sometimes, this cause that
>
> I am not sure if it's fair to say this is Layerscape specific
> behavior. Based on the xHCI spec, the spec indicates 1 event trb
> should be generated when IOC/ISP flag is set to 1 or an error occurs.

Ah, ISP flag is set if the pipe is from an IN endpoint. Currently we have:

        /* Only set interrupt on short packet for IN endpoints */
        if (usb_pipein(pipe))
            field |= TRB_ISP;

Can you verify that if removing the above codes, and without your
changes in this patch, the original issue can be resolved on LS1028?

> I will see if I can reproduce your issue on an x86 board.
>

Note this patch does not apply on top of u-boot/master. Please rebase.

> > function mishandle event TRB in next round call, then system hang due to
> > BUG() checking.
> >
> > This patch adds a loop to make sure the event TRB for last Transfer TRB has
> > to be handled in time.
> >
> > Signed-off-by: Ran Wang <ran.wang_1 at nxp.com>
> > ---
> >  drivers/usb/host/xhci-ring.c | 17 ++++++++++++++---
> >  1 file changed, 14 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> > index 092ed6e..d77e058 100644
> > --- a/drivers/usb/host/xhci-ring.c
> > +++ b/drivers/usb/host/xhci-ring.c
> > @@ -578,10 +578,13 @@ int xhci_bulk_tx(struct usb_device *udev, unsigned long pipe,
> >         int ret;
> >         u32 trb_fields[4];
> >         u64 val_64 = virt_to_phys(buffer);
> > +       void *last_transfer_trb_addr;
> > +       int available_length;
> >
> >         debug("dev=%p, pipe=%lx, buffer=%p, length=%d\n",
> >                 udev, pipe, buffer, length);
> >
> > +       available_length = length;
> >         ep_index = usb_pipe_ep_index(pipe);
> >         virt_dev = ctrl->devs[slot_id];
> >
> > @@ -701,7 +704,7 @@ int xhci_bulk_tx(struct usb_device *udev, unsigned long pipe,
> >                 trb_fields[2] = length_field;
> >                 trb_fields[3] = field | (TRB_NORMAL << TRB_TYPE_SHIFT);
> >
> > -               queue_trb(ctrl, ring, (num_trbs > 1), trb_fields);
> > +               last_transfer_trb_addr = queue_trb(ctrl, ring, (num_trbs > 1), trb_fields);
> >
> >                 --num_trbs;
> >
> > @@ -714,6 +717,7 @@ int xhci_bulk_tx(struct usb_device *udev, unsigned long pipe,
> >
> >         giveback_first_trb(udev, ep_index, start_cycle, start_trb);
> >
> > +again:
> >         event = xhci_wait_for_event(ctrl, TRB_TRANSFER);
> >         if (!event) {
> >                 debug("XHCI bulk transfer timed out, aborting...\n");
> > @@ -722,14 +726,21 @@ int xhci_bulk_tx(struct usb_device *udev, unsigned long pipe,
> >                 udev->act_len = 0;
> >                 return -ETIMEDOUT;
> >         }
> > -       field = le32_to_cpu(event->trans_event.flags);
> >
> > +       if ((void *)event->trans_event.buffer != last_transfer_trb_addr) {
>
> This should be:
>
> if ((void *)le64_to_cpu(event->trans_event.buffer) != last_transfer_trb_addr)
>
> > +               available_length -=
> > +                       (int)EVENT_TRB_LEN(le32_to_cpu(event->trans_event.transfer_len));
> > +               xhci_acknowledge_event(ctrl);
> > +               goto again;
> > +       }
> > +
> > +       field = le32_to_cpu(event->trans_event.flags);
> >         BUG_ON(TRB_TO_SLOT_ID(field) != slot_id);
> >         BUG_ON(TRB_TO_EP_INDEX(field) != ep_index);
> >         BUG_ON(*(void **)(uintptr_t)le64_to_cpu(event->trans_event.buffer) -
> >                 buffer > (size_t)length);
> >
> > -       record_transfer_result(udev, event, length);
> > +       record_transfer_result(udev, event, available_length);
> >         xhci_acknowledge_event(ctrl);
> >         xhci_inval_cache((uintptr_t)buffer, length);
> >

Regards,
Bin