[ltp] Thinkcentre M51 USB hotplug issue

Nate Bargmann linux-thinkpad@linux-thinkpad.org
Mon, 15 Nov 2010 06:27:38 -0600


* On 2010 15 Nov 03:20 -0600, Dmitry E. Mikhailov wrote:
> On Sunday 14 November 2010 18:55, Nate Bargmann wrote:
> > ThinkCentre M51
> 
> It's a Pentium4 on an Intel chipset.
> 
> ALL intel chipset P4 mobos this defect: insufficient ESD protection on 
> Southbridge's USB ports. Intel is to blame.
> 
> It means that sooner or later when you insert a USB device, something bad 
> happens:
> 1)USB controller damage - it works somewhat, but has problems
> 2)USB controller burnout - it's seen by the system, but the connected devices 
> doesn't
> 3)Southbridge burnout - motherboard is dead.
> 
> You have the 1st. It's going to progress if you try to use MoBo's USB ports. 
> Disable USB in BIOS and use your PCI controller.

That is interesting and not following hardware all that closely, not
something I knew about.  It certainly acts like a hardware issue as the
kernel never gives an indication of a hotplug event being seen upon
insertion into any of the mobo USB ports.  Still, I would think that if
the USB ports had suffered hardware damage that they would be dead all
around.  In this system any device inserted at system start in any port
is recognized and usable.  So what is different when Linux starts that
it sees the devices compared to later during hotplug that it can't?  Is
there some kind of hardware initialization at work here?

- Nate >>

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