linuxaudio.org

On 05/13/2012 07:45 PM, plutek wrote:

quoted text
> From: Robin Gareus

> Date: Sun, 13 May 2012 08:57:26 +0200

>

>> On 05/13/2012 03:13 AM, plutek wrote:

>>> From: Karsten Wiese

>>> Date: Sat, 12 May 2012 23:18:22 +0200

>>>

>>>> 2012/5/12 Clemens Ladisch :

>>>>> plutek wrote:

>>>>>> i've been running AVLinux5.0.3 on a ThinkPad T61p for a while now....

>>>>>> with an ART USB Dual Tube Pre, i can run Jack at 64 frames, 2 periods

>>>>>>

>>>>>> now i've got a new ThinkPad T520, and if i start jack on USB at 64*2

>>>>>> i get hundreds of xruns in seconds.

>>>>>

>>>>> Both machines run (I assume) the same software?  Then the problem is

>>>>> with the hardware, or its drivers.

>>>>>

>>>>> Please show the output of lspci and the contents of /proc/interrupts.

>>>>>

>>>>

>>>> Thinkwiki says its got a QM67. That does USB 1.1 via the "Rate

>>>> matching hub" and EHCI.

>>>> I guess linux's hub driver is the culprit.

>>>

>>> hmmmm.... shame.... lenovo specs said, of course, "USB 2.0".

>>> mrph.

>>>

>>> any way around this currently?

>>

>> yes,

>>

>> http://lists.linuxaudio.org/pipermail/linux-audio-dev/2010-October/02951...

>

> after i do:

>

> # cd /sys/bus/pci/drivers/ehci_hcd/

> # echo -n 0000:00:1d.0 > unbind

>

> ...the USB audio device no longer shows up in qjackctl.

>

> did i misunderstand?

No, not that I can tell. "0000:00:1d.0" is the USB hub/controller, right?
The idea is to use the uhci_hcd (USB1) driver instead of ehci_hcd

(USB2). -- Maybe the module is not loaded?
 `lsmod | grep  uhci_hcd`

 `ls /sys/bus/pci/drivers/uhci_hcd/`
If they're modules: `rmmod ehci_hcd; modprobe uhci_hcd`; that'll force

all USB ports into 1.X mode; may be worth a try before playing with

dedicated per port bindings.
Anyway, there might be something else going on: as both Karsten and

Clemens noted, these "Intel Corporation Cougar Point [..] controllers

use a different driver" and "There have been fixes recently.  Try

updating the kernel."
robin

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