Re: determine whether USB port is an internal Hub port

On Tue, 11 Dec 2007, Elias Humbolt wrote:

> I would need a way to determine which of my USB ports are actual native
> ports and which are internal USB hub ports. How can I achieve that
> easily?

What you're asking isn't clear.  What's supposed to be the difference
between a "native" port and an "internal hub" port?  Is an "internal"  
port supposed to be one that is permanently connected to a device
internal to the computer's case?

> The reason being is, that I want to investigate a theory to this bug:
> 
> ---
> Certain USB devices do not work properly, or do not work at all, while
> the ehci_hcd module is loaded.
> 
> A solution is to unload the ehci_hcd module, which is loaded every time
> the computer starts, using the command 'sudo modprobe -r ehci_hcd'. This
> works fine but unfortunatly ehci-hcd is necessary for using USB 2.0, so
> you lose USB 2.0 features.
> 
> Get more info at https://bugs.launchpad.net/bugs/88746

That bug report contains submissions from at least a dozen different 
people, reporting different problems with different symptoms and 
generally contradicting one another.  It's very hard to make any sense 
out of it.

In any case, your basic premise is wrong.  EHCI works just fine on my 
computers.

> ---
> 
> This bug is bugging me for about a year now. However, this bug is not
> showing up on all my USB ports. As this problem has be reported to show
> up particularly on USB Hubs, I suspect it might only show up on those of
> my USB ports that are actually internal USB Hub ports. I would like to
> verify that theory but would need advice on how to do that.
> 
> Maybe somebody could also have a look at the bug report mentioned. This
> bug has been reported beginning of this year in the Ubuntu bug tracker.
> Up till now, it does not seem like anybody has laid hand on it yet.
> 
> I also have no idea if this bug report even made it upstream. Does
> Ubuntu/Launchpad have a facility to escalate bugs to the kernel bug
> tracker? I am somehow loosing faith in the whole Launchpad approach.
> Maybe you could advise if I should rather report kernel specific bugs
> directly to the kernel bug tracker instead of hoping the Ubuntu guys
> will take care of channeling it upstream.

I have no idea what facilities Unbuntu/Launchpad has for escalating 
bugs.  If you want to report a problem to the kernel developers, the 
best approach is for you to do it yourself.

You can begin by using a vanilla kernel (one obtained directly from 
www.kernel.org) instead of a distribution kernel.  Let us know what 
version it is (don't use anything earlier than 2.6.23).  Be sure to 
enable CONFIG_USB_DEBUG when building the kernel.  In your report, 
include the output from dmesg showing the problem as it occurs.

Alan Stern


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