Re: [Linux-usb-users] reset low speed USB device using uhci_hcd (fwd)

Re: [Linux-usb-users] reset low speed USB device using uhci_hcd (fwd)

[Alan Stern]

Take a look at the message below.  It turned out that the USB errors went 
away when Claas removed a USB extension cable, but that doesn't explain 
the peculiar keyboard-mouse interaction -- especially since it's a PS/2 
keyboard.  Any ideas?

Alan Stern

---------- Forwarded message ----------
Date: Fri, 16 Mar 2007 10:43:22 +0100
From: Claas Langbehn <claas@rootdir.de>
To: linux-usb-users@lists.sourceforge.net
Subject: Re: [Linux-usb-users] reset low speed USB device using uhci_hcd

Hello,

I've got the same problem. I get this message a lot in dmesg:
usb 2-2: reset low speed USB device using uhci_hcd and address 3

$ lsusb
Bus 003 Device 001: ID 0000:0000 
Bus 002 Device 003: ID 046d:c001 Logitech, Inc. N48/M-BB48 [FirstMouse Plus]
Bus 002 Device 002: ID 03f0:0317 Hewlett-Packard LaserJet 1200
Bus 002 Device 001: ID 0000:0000 
Bus 004 Device 001: ID 0000:0000 
Bus 001 Device 001: ID 0000:0000

I already recompiled my kernel to not use CONFIG_PREEMPT_NONE=y, but that
did not help.

My mainboard is a VIA EPIA-EX15000G with the CX700M2 chipset, see:
$ lspci | grep USB
00:10.0 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 
Controller (rev 90)
00:10.1 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 
Controller (rev 90)
00:10.2 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 
Controller (rev 90)
00:10.4 USB Controller: VIA Technologies, Inc. USB 2.0 (rev 90)

$ dmesg | grep -i USB
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
USB Universal Host Controller Interface driver v3.0
uhci_hcd 0000:00:10.0: new USB bus registered, assigned bus number 1
usb usb1: configuration #1 chosen from 1 choice
hub 1-0:1.0: USB hub found
uhci_hcd 0000:00:10.1: new USB bus registered, assigned bus number 2
usb usb2: configuration #1 chosen from 1 choice
hub 2-0:1.0: USB hub found
uhci_hcd 0000:00:10.2: new USB bus registered, assigned bus number 3
usb usb3: configuration #1 chosen from 1 choice
hub 3-0:1.0: USB hub found
ehci_hcd 0000:00:10.4: new USB bus registered, assigned bus number 4
ehci_hcd 0000:00:10.4: USB 2.0 started, EHCI 1.00, driver 10 Dec 2004
usb usb4: configuration #1 chosen from 1 choice
hub 4-0:1.0: USB hub found
usb 2-1: new full speed USB device using uhci_hcd and address 2
usb 2-1: configuration #1 chosen from 1 choice
usb 2-2: new low speed USB device using uhci_hcd and address 3
usb 2-2: configuration #1 chosen from 1 choice
drivers/usb/class/usblp.c: usblp0: USB Bidirectional printer dev 2 if 0 
alt 1 proto 2 vid 0x03F0 pid 0x0317
usbcore: registered new interface driver usblp
drivers/usb/class/usblp.c: v0.13: USB Printer Device Class driver
usbcore: registered new interface driver hiddev
input: USB HID v1.00 Mouse [Logitech] on usb-0000:00:10.1-2
usbcore: registered new interface driver usbhid
drivers/usb/input/hid-core.c: v2.6:USB HID core driver
usb 2-2: reset low speed USB device using uhci_hcd and address 3
usb 2-2: reset low speed USB device using uhci_hcd and address 3 (this 
message is repeated a lot of times!)


Another problem I have is:
When pressing and releasing a key, the computer 
<http://forums.viaarena.com/messageview.aspx?catid=28&threadid=76926&enterthread=y#> 
does not realize the key release and therefore the key is repeated until 
I press a key again. That's very annoying. My keyboard is connected 
using PS/2. I know it's not USB, but I read that Gordon Messmer has the 
same problems, so maybe mentioning it may be useful.


I am using kernel 2.6.21-rc3 with 
x86_64-mm-add-an-option-for-the-via-c7-which-sets-appropriate-l1-cache.patch.

I am going to post usbmon outputs with a second email (after a reboot)


Claas

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Re: [Linux-usb-users] reset low speed USB device using uhci_hcd (fwd)

[Dmitry Torokhov]

On 3/16/07, Alan Stern <stern@rowland.harvard.edu> wrote:
> Take a look at the message below.  It turned out that the USB errors went
> away when Claas removed a USB extension cable, but that doesn't explain
> the peculiar keyboard-mouse interaction -- especially since it's a PS/2
> keyboard.  Any ideas?
>

Going on a limb here - faulty USB cable causes USB resets which throws
off legacy emulation (which is done in SMM as well as KBC controller)
which causes KCB to lose bytes. I would expect also seeing some
keypresses not being registered but losing release is much more
visible...

-- 
Dmitry

Re: [Linux-usb-users] reset low speed USB device using uhci_hcd (fwd)

[Alan Stern]

On Fri, 16 Mar 2007, Dmitry Torokhov wrote:

> On 3/16/07, Alan Stern <stern@rowland.harvard.edu> wrote:
> > Take a look at the message below.  It turned out that the USB errors went
> > away when Claas removed a USB extension cable, but that doesn't explain
> > the peculiar keyboard-mouse interaction -- especially since it's a PS/2
> > keyboard.  Any ideas?
> >
> 
> Going on a limb here - faulty USB cable causes USB resets which throws
> off legacy emulation (which is done in SMM as well as KBC controller)
> which causes KCB to lose bytes. I would expect also seeing some
> keypresses not being registered but losing release is much more
> visible...

It's possible.  But the USB drivers try to take control of the host 
controllers away from the SMM BIOS.  How could legacy support work with 
both SMM and the Linux USBHID system trying to handle it?

Alan Stern

Re: [Linux-usb-users] reset low speed USB device using uhci_hcd (fwd)

[Claas Langbehn]

Hello!

>> Going on a limb here - faulty USB cable causes USB resets which throws
>> off legacy emulation (which is done in SMM as well as KBC controller)
>> which causes KCB to lose bytes. I would expect also seeing some
>> keypresses not being registered but losing release is much more
>> visible...
>>     
>
> It's possible.  But the USB drivers try to take control of the host 
> controllers away from the SMM BIOS.  How could legacy support work with 
> both SMM and the Linux USBHID system trying to handle it?
>   
Please tell me what I can do to help to debug this strange behaviour.
Repuducing the USB resets is easy, but reproducing the PS/2 influence
takes long, since its hardly visible.


many regards,
claas

Re: [Linux-usb-users] reset low speed USB device using uhci_hcd (fwd)

[Alan Stern]

On Fri, 16 Mar 2007, Claas Langbehn wrote:

> Hello!
> 
> >> Going on a limb here - faulty USB cable causes USB resets which throws
> >> off legacy emulation (which is done in SMM as well as KBC controller)
> >> which causes KCB to lose bytes. I would expect also seeing some
> >> keypresses not being registered but losing release is much more
> >> visible...
> >>     
> >
> > It's possible.  But the USB drivers try to take control of the host 
> > controllers away from the SMM BIOS.  How could legacy support work with 
> > both SMM and the Linux USBHID system trying to handle it?
> >   
> Please tell me what I can do to help to debug this strange behaviour.
> Repuducing the USB resets is easy, but reproducing the PS/2 influence
> takes long, since its hardly visible.

My advice is don't do anything and don't worry about it.  It really isn't 
an important problem.

Alan Stern