Cheap USB-hub - crashes USB when alone


GuSec

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Dec 29, 2008
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Hi there, I'm one of the new pandora-owners (but an old preorderer)!


Yesterday I went on a hunt after an OTG-cable. Since it proved impossible to find (mini-A is NOT standard anymore) and my own soldering plans got ruined once i found out that my cable lacked pin 4 entirely, I decided to buy a very cheap USB 2.0 2-port hub.


When I came home i discovered that it didn't work. It was not listed by lsusb and attaching devices turned on no lights (it has got one diode per port). These attached devices were not discovered by my Pandora either.


I tried and then after a while I found a solution. All I had to do was attach the unit WITH devices attached! The lights were on and all devices worked perfectly with my Pandora. The frustrating fact is that if I by mistake insert it without any devices the USB-port stops functioning entirely and I must reboot the Pandora before even an ordinary USB 2.0 device will be discovered again (TOTAL silence from dmesg). This is also the case if I remove both devices while the hub is connected.


So it seems that one port must always be occupied at all times the USB-hub is connected. So my question is of course how this can be and if there is anything I can do to fix it? Finally, I would very much appreciate some help on how I can restart the USB-modules and whatnot from the terminal to not have to do a complete reboot!


lsusb before hub:

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub


Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub


dmesg right after I only connect the hub:

[ 586.598388] usb 1-2: new high-speed USB device number 9 using ehci-omap


[ 586.755676] usb 1-2: New USB device found, idVendor=1a40, idProduct=0101


[ 586.755706] usb 1-2: New USB device strings: Mfr=0, Product=1, SerialNumber=0


[ 586.755706] usb 1-2: Product: USB 2.0 Hub


[ 586.758819] hub 1-2:1.0: USB hub found


[ 586.759063] hub 1-2:1.0: 4 ports detected


then checking with lsusb:

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub


Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub


back to dmesg:

[ 602.918731] usb 1-2: USB disconnect, device number 9


The USB is now ruined, so I reboot and then check dmesg after I connect the hub with both a mouse and a keyboard already attached:

[ 207.848358] usb 1-2: new high-speed USB device number 2 using ehci-omap


[ 208.005828] usb 1-2: New USB device found, idVendor=1a40, idProduct=0101


[ 208.005859] usb 1-2: New USB device strings: Mfr=0, Product=1, SerialNumber=0


[ 208.005859] usb 1-2: Product: USB 2.0 Hub


[ 208.008758] hub 1-2:1.0: USB hub found


[ 208.009185] hub 1-2:1.0: 4 ports detected


[ 208.293792] usb 1-2.1: new full-speed USB device number 3 using ehci-omap


[ 208.415191] usb 1-2.1: New USB device found, idVendor=09da, idProduct=0080


[ 208.415222] usb 1-2.1: New USB device strings: Mfr=1, Product=2, SerialNumber=0


[ 208.415222] usb 1-2.1: Product: USB Mouse


[ 208.415252] usb 1-2.1: Manufacturer: A4Tech


[ 208.425048] input: A4Tech USB Mouse as /devices/platform/usbhs-omap.0/ehci-omap.0/usb1/1-2/1-2.1/1-2.1:1.0/input/input8


[ 208.429229] generic-usb 0003:09DA:0080.0001: input: USB HID v1.11 Mouse [A4Tech USB Mouse] on usb-ehci-omap.0-2.1/input0


[ 208.512359] usb 1-2.3: new low-speed USB device number 4 using ehci-omap


[ 208.635437] usb 1-2.3: New USB device found, idVendor=0b38, idProduct=0003


[ 208.635467] usb 1-2.3: New USB device strings: Mfr=0, Product=1, SerialNumber=0


[ 208.635467] usb 1-2.3: Product: USB-compliant keyboard


[ 208.645416] input: USB-compliant keyboard as /devices/platform/usbhs-omap.0/ehci-omap.0/usb1/1-2/1-2.3/1-2.3:1.0/input/input9


[ 208.651458] generic-usb 0003:0B38:0003.0002: input: USB HID v1.10 Keyboard [uSB-compliant keyboard] on usb-ehci-omap.0-2.3/input0


[ 208.676177] input: USB-compliant keyboard as /devices/platform/usbhs-omap.0/ehci-omap.0/usb1/1-2/1-2.3/1-2.3:1.1/input/input10


[ 208.677307] generic-usb 0003:0B38:0003.0003: input: USB HID v1.10 Mouse [uSB-compliant keyboard] on usb-ehci-omap.0-2.3/input1


lsusb:

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub


Bus 001 Device 002: ID 1a40:0101 TERMINUS TECHNOLOGY INC.


Bus 001 Device 003: ID 09da:0080 A4 Tech Co., Ltd


Bus 001 Device 004: ID 0b38:0003


Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub


Everything works! Removing the keyboard and then dmesg:

[ 390.477722] usb 1-2.3: USB disconnect, device number 7


lsusb:

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub


Bus 001 Device 005: ID 1a40:0101 TERMINUS TECHNOLOGY INC.


Bus 001 Device 006: ID 09da:0080 A4 Tech Co., Ltd


Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub


I can now attach the keyboard again without a problem and remove the mouse, but I can't detach both! Strange problem, huh?
 
Last edited by a moderator:
I think its a pandora-bug that makes the USB system jam when given an empty hub, rather than anything dto do with your hub.


For other information, wait for one of the devs to come along :)


You might want to put spoiler tags round those long quotes, like so:



Code:
[spoiler] foo bar [/spoiler]
 
Last edited by a moderator:
This has been reported with other hubs when plugged in without a device.. Until it can be fixed, just remember to plug the devices in before you plug in the hub to the Pandora.
 
Yes, I'm going to put them in spoilers instead of quotes in the future, thank you! Ah, great that it's a known issue, i'll just wait for a fix then. Thank you for the quick answers!
 
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