Re: Generic USB 2.0 hub showing up as USB 1.1

"VanguardLH" <VanguardLH@[EMAIL PROTECTED]
> wrote in message 
news:Ob$f3XtSIHA.1184@[EMAIL PROTECTED]
> "Yousuf Khan" <bbbl67@[EMAIL PROTECTED]
> wrote in message 
> news:ipSdnROWzJM6I-vaRVn_vwA@[EMAIL PROTECTED]
>>I have two generic 4-****t USB hubs that are supposed to be USB 2.0 
>>compliant. The older one is fine, works as advertised. Meanwhile the
newer 
>>one sometimes shows up under the USB 2.0 root hub (i.e. "Standard
Enhanced 
>>PCI to USB Host Controller"), or usually it shows up under the slower 
>>"Standard OpenHCD USB Host Controller" (USB 1.1).
>>
>> My motherboard (Asus M2NPV-VM) USB ****ts are all USB 2.0 compliant, and

>> they individually auto-detect whether they need to switch down to USB
1.1 
>> speeds. I'm using a Microsoft tool called UVCView under Windows XP to 
>> display the details of the USB devices, including the hubs and
roothubs.
>>
>> According to UVCView, the older hub and newer hub seem to have the same

>> chipset vendor (idVendor = "Genesys Logic, Inc."), although externally 
>> they look quite different and have different brand names. So I'm not
sure 
>> why one would be consistently USB 2.0 compliant, while the other one is

>> not.
>>
>> Now another interesting thing I noticed is that the inconsistent hub
will 
>> only show up as USB 2.0-compliant after I boot into Windows after
having 
>> previously rebooted from Ubuntu 7.10 Linux (dual-boot system). So maybe

>> Linux does something to the device that puts it right. But when I list 
>> the devices while in Linux I see that it is listed under USB 1.1 just 
>> like when in Windows. I have no idea why Linux leaves the hub fixed for

>> Windows, but doesn't fix it for itself?!
>>
>> Any idea what's going on with this hub?
>>
>> Yousuf Khan
>
>
> Are both of these a self-powered hub (i.e., they have a power adapter)
or 
> a low-power hub that relies on the current supplied from the USB 
> controller at the motherboard?  If they are bus-powered hubs, they
CANNOT 
> be on the same USB controller.  Each controller provides 2 ****ts 
> (channels) but these 2 ****ts still share the same controller and so both

> are limited by a total amperage that can be supplied by the same 
> controller.

Sorry, but that isn't true.  Bus powered hubs are deliberately limited to 
100mA per ****t precisely so that they don't exceed the 500mA available
from 
the root hub ****t.  You can connect 8 of them to the 8 ****ts of the USB2 
enhanced root ****ts if you want to.  The current available from any root 
****t is 500mA per ****t regardless of what is connected to the others.  In 
practice you can get a bit more than that before the over current
protection 
kicks in.   Current not used on one ****t does not become available to the 
others because the over current protection is implimented on a per ****t 
basis.

Of course, what you can't do is to *cascade* bus powered hubs.