# port disabled by hub (EMI?), re-enabling... (USB problems)

## Xaid

Hi,

I'm having some strange issues with one of my USB devices, its a Belkin UPS (connected directly not through an external USB hub).

When its plugged in, its detected by the kernel (this is shown as below):

```

usb 3-2: new low speed USB device using uhci_hcd and address 5

hiddev96: USB HID v1.11 Device [Belkin UPS] on usb-0000:00:1d.1-2

```

but after a few minutes, the device gets disconnected and reconnected again for no apparent reason,

here's the entry from dmesg:

```

hub 2-0:1.0: port 1 disabled by hub (EMI?), re-enabling...

usb 2-1: USB disconnect, address 9

usb 2-1: new low speed USB device using uhci_hcd and address 10

hiddev96: USB HID v1.11 Device [Belkin UPS] on usb-0000:00:1d.0-1

```

The kernel version I'm running is gentoo-hardened-2.6.11-r15 and I'm using udev.

I have all the USB drivers needed compiled into the kernel.

does anyone else have this problem? any known fix for it?

Edit: changed title.Last edited by Xaid on Thu Aug 04, 2005 4:16 am; edited 1 time in total

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## Xaid

I think I know what the problem is, it seems that connecting a slow USB device and a fast one on the same hub doesn't work very well, I had a USB2 scanner connected besides that Belkin UPS which is USB1 and I was seeing those disconnections, if I plug only one of them, I have no problems.

They're not connected to an external hub but to my box directly, but it seems that doesn't matter.

If anyone knows of a fix for this situation (beside having just one device plugged in at any time) then I'd appreciate any tips on how you got it working.

Edit: I think another workaround is to disable EHCI (USB 2) but that only makes sense if all your USB devices are USB 1 or if you don't mind the major speed difference.

Edit2: I just noticed that I got this error again when looking at dmesg output, but the interval is a lot longer, before, it was a disconnection per 30 mins - 1 hour, but now its just this one in 4 hours, so its definately less, but it still happens. I doubt its a hardware problem, but I'm not sure where the problem is.

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## d4rkwingduck

Hi i am also experiencing this problem with my laptop. Basically after a fresh boot everything seems to be working fine, but after a while when the temperature is high i get that error message every second  :Sad: . I've just tried to disable all usb support but i still get it ... anyways i am too tired at the moment to check it furture ill continue tomorrow.

EDIT:Sorry was booting wrong kernel   :Embarassed: 

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## bbe

I too get this error, it seems to be my mouse. I also get hardlocks sometimes shortly after this has happened, though this might be RAM related. And I agree that it seems to be temperature related. Did anyone solve this issue?

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## drekka

Hi all, I have been having this problem as well, ever since I upgraded to Gentoo 2005.1 so I'm wondering if it is an issues with the 2.6 kernels.

Hardware:

Asus A7N8X mobo

Happy hacking Lite KB

M$ Intellimouse Explorer 3

I've tried a number of different arrangements I.e. keyboard and mouse seperate into box, mouse into keyboard into box etc. Nothing seems to stop the random crashing. Box temps look fine to me.

This is a serious issue.

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## drekka

Found this in the usb code:

```

/*

             * EM interference sometimes causes bad shielded USB devices to 

             * be shutdown by the hub, this hack enables them again.

             * Works at least with mouse driver. 

             */

            if (!(portstatus & USB_PORT_STAT_ENABLE) && 

                (portstatus & USB_PORT_STAT_CONNECTION) && (dev->children[i])) {

               err("already running port %i disabled by hub (EMI?), re-enabling...",

                  i + 1);

               usb_hub_port_connect_change(hub, i, portstatus, portchange);

            }

         }

```

It sounds like the error is being generated by a recovery routine. However I don't know enough about the kernel drivers and this one in particular to figure out the issue. Perhaps a C wizard can take a look at this and give us a better understanding of the problem.

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