Hi Alan, Oliver,
On Mon, Jul 20, 2009 at 4:40 PM, Alan Stern<stern@xxxxxxxxxxxxxxxxxxx> wrote:
> On Mon, 20 Jul 2009, Oliver Neukum wrote:
>
>> Am Montag, 20. Juli 2009 09:56:48 schrieb Manuel Lauss:
>> > Hi Oliver,
>> >
>> > While testing a CDC-ACM usb device I encoutered these warnings when
>> > closing the ttyACM device:
>> >
>> > WARNING: at linux-2.6.git/drivers/usb/host/ehci-hcd.c:908
>> > ehci_urb_dequeue+0x190/0x198()
>> > Modules linked in:
>> > Call Trace:
>> > [<80107158>] dump_stack+0x8/0x34
>> > [<8012a468>] warn_slowpath_common+0x70/0xb0
>> > [<802e3968>] ehci_urb_dequeue+0x190/0x198
>> > [<802ced70>] usb_hcd_unlink_urb+0xc0/0xf4
>> > [<802d0320>] usb_kill_urb+0x54/0xfc
>> > [<802ec9d8>] acm_port_down+0x21c/0x278
>> > [<802ecd94>] acm_tty_close+0x5c/0xb8
>> > [<8025f314>] tty_release_dev+0x17c/0x580
>> > [<8025f728>] tty_release+0x10/0x20
>> > [<8018f078>] __fput+0xf4/0x248
>> > [<8018af78>] filp_close+0x68/0x98
>> > [<8018b054>] sys_close+0xac/0xd8
>> > [<80102260>] stack_done+0x20/0x3c
>>
>> This points to an ehci problem. Alan?
>
> Yes indeed. This appears to have been caused by a recent change I
> made. Previously the WARN_ON could never be triggered, but now it can
> and I didn't realize it.
>
> Let me guess: This CDC-ACM device runs at full speed and it is behind a
> high-speed hub, right?
Correct.
> The patch below will certainly remove the warning; the question is
> whether ehci-hcd will continue to work correctly. Some testing would
> be appreciated. In particular, try to set up the conditions that would
> cause the warning, and afterward do "rmmod ehci-hcd". That should
> cause any remaining errors to surface.
This is what I get. Additionally, after re-inserting ehci-hcd I get no more
responses from the ACM device, although it is correctly detected. Other
devices (mouse, usb storage) continue to work.
# rmmod ehci_hcd
au1xxx-ehci au1xxx-ehci.0: remove, state 1
usb usb2: USB disconnect, address 1
usb 2-1: USB disconnect, address 2
usb 2-1.2: USB disconnect, address 3
au1xxx-ehci au1xxx-ehci.0: dma_pool_destroy ehci_qtd, 8714f000 busy
au1xxx-ehci au1xxx-ehci.0: dma_pool_destroy ehci_qh, 871b9000 busy
au1xxx-ehci au1xxx-ehci.0: USB bus 2 deregistered
# modprobe ehci-hcd
ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
Platform driver 'au1xxx-ehci' needs updating - please use dev_pm_ops
au1xxx-ehci au1xxx-ehci.0: Au1xxx EHCI
au1xxx-ehci au1xxx-ehci.0: new USB bus registered, assigned bus number 1
au1xxx-ehci au1xxx-ehci.0: irq 37, io mem 0x14020200
au1xxx-ehci au1xxx-ehci.0: USB 0.0 started, EHCI 1.00
usb usb1: configuration #1 chosen from 1 choice
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 2 ports detected
usb 1-1: new high speed USB device using au1xxx-ehci and address 2
usb 1-1: configuration #1 chosen from 1 choice
hub 1-1:1.0: USB hub found
hub 1-1:1.0: 4 ports detected
usb 1-1.2: new full speed USB device using au1xxx-ehci and address 3
usb 1-1.2: configuration #1 chosen from 1 choice
cdc_acm 1-1.2:1.0: ttyACM0: USB ACM device
Thanks!
Manuel Lauss
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
