2 out of 4 usb sockets work

[Robert P. J. Day]

On Sun, 27 Jan 2008, William Murray wrote:

>
>   Hello all,
>           I am trying to understand a laptop with 4 USB ports,
> apparently identical, but all 4 work under windows and only 2 under F8.
> If I look in 'hwbrowser' I see 3 controllers, (2 UHCI and 1 EHCI I
> think)  but no 'USB UHCI #n' entries like I expect.
>   cat /proc/bus/usb/devices shows up 3 controllers, and the USB mouse I
> have plugged in.
>   It ALSO shows a device "0baa 0158", which is somehow a Realtek disk (I
> don't think there IS one) but not "0bda 8187" (or is it 8189) that I
> think the wireless card should be registered as.

  i'm thinking this would be a good time for someone to point us at a
decent tutorial on USB under linux since, as i was poking around, i
began to get a bit confused.

  i have a gateway laptop with 4 USB ports (all 4 of which work under
f8, bwahahahaha!!).  currently plugged in:

* io/magic 250G HD
* keyboard
* logitech optical mouse
* brother printer

all fully functional.

  the USB-related output from "lspci":

...
00:1d.0 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #1 (rev 02)
00:1d.1 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #2 (rev 02)
00:1d.2 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #3 (rev 02)
00:1d.3 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #4 (rev 02)
00:1d.7 USB Controller: Intel Corporation 82801G (ICH7 Family) USB2 EHCI Controller (rev 02)
...

  my first (admittedly uneducated) guess was that each of those UHCI
controllers was associated with a distinct port.  but:

$ lsusb -t
Bus#  5
`-Dev#   1 Vendor 0x0000 Product 0x0000
Bus#  4
`-Dev#   1 Vendor 0x0000 Product 0x0000
Bus#  3
`-Dev#   1 Vendor 0x0000 Product 0x0000
  |-Dev#   4 Vendor 0x04f9 Product 0x0028
  `-Dev#   3 Vendor 0x046d Product 0xc00e
Bus#  2
`-Dev#   1 Vendor 0x0000 Product 0x0000
  `-Dev#   3 Vendor 0x413c Product 0x2005
Bus#  1
`-Dev#   1 Vendor 0x0000 Product 0x0000
  `-Dev#   4 Vendor 0x067b Product 0x2506
$

  so bus 1 and bus 2 each have one of the devices, but bus 3 controls
two of them.  i guess i'm just not conversant enough with how USB
devices are allocated to busses and devices.  is there a decent online
page that explains how that allocation works?  especially how it might
differ when devices are already attached at boot time versus what
happens when they're hot-plugged?  thanks.

rday
--

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Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA

Home page:                                         http://crashcourse.ca
Fedora Cookbook:    http://crashcourse.ca/wiki/index.php/Fedora_Cookbook
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