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Old 01-17-2010, 09:36 PM   #1
damien_d
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Limiting USB speed to 12Mbps ("USB 1.1")


Hello all,

I'm currently investigating what we suspect is a USB signal integrity issue (on an embedded board) and we're looking at a way that we can limit the USB speed to 12Mbps for a particular device.

According to the Linux USB FAQ, we can limit the speed of the entire lot by removing the EHCI module, but if possible I'd like to do this on a per-port basis?

Doe anyone know of a method to do this, for example, some value in the sys filesystem, or any modprobe parameters?

[edit] I should mention that the devices that I want to slow down are downstream of a High-speed hub [/edit]

-- Damien

Last edited by damien_d; 01-17-2010 at 11:58 PM.
 
Old 01-18-2010, 10:46 AM   #2
zordrak
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Wouldn't the use of a USB1 hub allow you to do your investigation without such a low-level manipulation of the OS?
 
Old 01-19-2010, 12:30 AM   #3
damien_d
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Quote:
Originally Posted by zordrak View Post
Wouldn't the use of a USB1 hub allow you to do your investigation without such a low-level manipulation of the OS?
The hub is soldered onto the board, and there are some soldered USB slaves downstream of the hub that we want to test.
 
  


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