On Mon, Sep 06, 2010 at 03:01:27PM +0900, Takahiro Nishikawa wrote:
> Hi,
>
> I am trying to use the usb xhci driver on powerpc(P2020RDB) board.
> But I experience the same problem "devices are not detected".
> It was posted in July on this ML.
>
> Does anyone try to fix the problem?
Hi Nishikawa,
The xHCI driver currently doesn't work on big-endian systems. It's a
known bug, but I haven't had time to look into it. Patches are welcome.
> It seems to be correct until "Finished xhci_run".
> In "In xhci_handle_event" it does not handle the event correctly.
>
> if ((event->event_cmd.flags & TRB_CYCLE) !=
> xhci->event_ring->cycle_state) {
> xhci->error_bitmask |= 1 << 2;
> return;
> }
>
> The bit0 of event->event_cmd.flags is not set though the bit0 of xhci->event_ring->cycle_state is set. The handler returns with the error, and receives the same event again and again.
>
> I cannot find the reason why event_cmd.flags is zero.
The xHCI host controller will write a little endian value into the
32-bit flags portion of the event. But I wonder if the math is correct
on a big endian system. When xhci->event_ring->cycle_state is first
written, does it need to be wrapped in a cpu_to_le() call? Also, does
the TRB_CYCLE need to be wrapped?
Sarah Sharp
xHCI driver maintainer
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