[SLOF] xhci in slof issues

[Nikunj A Dadhania]

Thomas Huth <thuth at redhat.com> writes:

> On 21.04.2016 12:36, Dinar Valeev wrote:
>> Hi,
>> 
>> While trying to fix my usb over vnc automated issues, I switched to
>> xhci, which helped a lot OS wise, but I see a regression in SLOF.
>> 
>> As you can see [1] we want to type an install repo url.  But at some
>> point capitalization of some characters are lost. Nope
>> openSUsE-tumbleweed instead of openSUSE-Tumbleweed.
>
> I recently also hit a problem with XHCI keyboard ... and maybe they are
> related. My problem is that "key?" is incredibly slow when using XHCI.
> For example, run the following Forth code at the SLOF prompt:
>
>  get-msecs 10 0 do key? . cr loop get-msecs swap - .d cr
>
> With XHCI, this takes more than 7.5 seconds to finish here, while with
> OHCI, this loop finishs within 400ms!
>
> Nikunj, do you have a clue what might be wrong here?

Nothing that comes out immediately, i was reviewing the code, here is
the call chain:

usb_key_available()
 ->usb_poll_key()
    ->usb_poll_intr()
      ->xhci_poll_intr()
        ->xhci_poll_event() (there is a 5sec timeout, which obviously
                             its not hitting).

                             Either this is taking around 700msec per
                             call, which looks very wierd.

Will spend some more time and debug.

Regards
Nikunj