[nycbug-talk] Soekris/PCEngines-ALIX USB Bug
Miles Nordin
carton at Ivy.NET
Fri Aug 8 14:21:44 EDT 2008
AIUI, disabling ehci just makes it usb 1.x speed.
If you look at how the ports attach, usb 2.0 controllers pretend to be
two chips, a 2.0 controller and a 1.x controller. They then pervert
the tree of controllers, hubs, hubs, devices before presenting it to
the drivers. Depending on the speed of the device plugged to a single
port, that device will appear to attach to the hub tree rooted at
either one controller or the other.
I think it is weirder than that, or not exactly as I've said. The two
sides are not mirror images. On one side they pretend to be one
controller with a 4-port hub attached, and on the other side to be 4
controllers with no hub attached. :/
i don't know why the Central Committe Controlling USB pulled all this
nonsense. maybe it helps the keyboard work at boot without forcing
the chinese to rewrite their fragile BIOS's?
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