Greetings,
On Tuesday 30 October 2001 00:20, [EMAIL PROTECTED] wrote
> Hi David, Nemosoft,
>
> First of all thanks for your answers. I hope we can get to the bottom of
> this weirdness!
>
> I applied the patch to pwc-if.c and enabled CONFIG_DEBUG_SLAB. I hope the
> resulting messages file means more to you than it does to me ;-)
[snip]
[excerpt from log]
Oct 29 23:53:24 wereldvreemd kernel: usb-ohci.c: USB-error/status: 8 :
c167d180
Oct 29 23:53:24 wereldvreemd kernel: usb-ohci.c: USB-error/status: 8 :
c167d140
Oct 29 23:53:24 wereldvreemd kernel: usb-ohci.c: RET URB:[9cc2] dev: 3,ep:
4-I,type:ISOC,flags: 2,len:6208/9600,stat:0(0)
Oct 29 23:53:24 wereldvreemd kernel: usb-ohci.c: data(6208/9600): db 8f 21
2a d4 38 42 23 09 0d 24 34 92 d0 40 42... stat:0
Oct 29 23:53:24 wereldvreemd kernel: pwc Iso frame 0 of URB has error -18
Oct 29 23:53:24 wereldvreemd kernel: pwc Iso frame 1 of URB has error -18
Hmm, this is kinda weird... When the URB is returned to the user driver
handler, it's state is 0 (no error), yet two (and often one) TD has an
error. -18 is -EXDEV. This status is set in 2 places in usb-ohci.c, around
line 500 (just before the driver callback handler is called), and line 600,
in sohci_submit_urb():
for (i = 0; i < urb->number_of_packets; i++) {
urb->iso_frame_desc[i].actual_length = 0;
urb->iso_frame_desc[i].status = -EXDEV;
}
I got a hunch... I'm using a circular linked list of 2 URBs, and it is my
guess the auto-urb submission is too late, or out of sync with the TD
pointer; in effect, the chip starts filling data before the URB is actually
linked into the TD structure, leaving the status for the first one or two
TDs at -EXDEV.
Try changing the status value about to something weird, like -200 and see
if that shows up in the log. If so, we have at least narrowed the problem
down a bit.
Second, in pwc.h try to change MAX_ISO_BUFS to 3, in stead of 2. Maybe 2
URBs is simply too little for this chip, and it needs a bit more headroom.
Mind you, I know next to nothing about the OHCI chip and its architecture;
I'm just making educated guesses :)
- Nemosoft
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