Internal USB Hub resetting

[ags131]

Hello, I just got my second Pi in the mail and am having problems. I hav a Lapdock that I'm running the pi on, I power the Pi by the usb backfeed. I have a 120GB SSD connected to the lapdock hub via USB,
The problem im having is the USB hub in the Pi keeps resetting, it losing connection, kernel spits out long logs of failure to connect to devices, then it starts working again and reconnects all usb devices. My other Pi with same exact SD card and plugged into same Lapdock works just fine. I have put a fresh Wheezy install on a card to verify that it wasn't my OS setup, I still lose USB connection. I have tried without USB SSD also but same results. The only USB devices connected besides the SSD are the Lapdock internal hub, mouse, and keyboard.
I have not overclocked this Pi yet so that can be ruled out.

Any Ideas? Is this just a faulty USB chip? Or something else?

[ags131]

Update:
I've got a kernel.log from Arch. I installed arch to see if it was a debian specific problem, but same exact results. (Kernel.log is the same as dmesg)
Kernel.log http://pastebin.com/raw.php?i=3VUG1BK2
If you need more info I can do limited debugging from the lapdock, but can also connect to UART for a console.

To clarify my setup, its layed out like this:
Raspi => Lapdock Internal Hub => USB SSD (Same problem without this too)
=> Lapdock USB Touchpad
=> Lapdock USB Keyboard

When USB goes wonky so does the keyboard and mouse, they stop responding at all.
I have tried unplugging and replugging the lapdock (Using a usb cable to keep power to PI) but no result.

[davidmam]

Can you measure the voltage between T1 and T2 on the Pi? It is entirely possible that you have a poor USB cable that is fine for data but not for power.

This is possibly one of the most common reasons for failure and should be the first to be checked.

[captainhooyah]

I'm having the same issue. The Pi will work fine for 1-5 minutes, then the usb goes out for a couple seconds, then it comes back, it will work for a couple seconds and go again, eventually it won't come back on.

I kept restarting it and measuring voltage at tp1 and tp2 while it did this on then off thing, and I noticed that it seemed like it started happening sooner and sooner, leading me to think that maybe it's has something to do with some thermal fuse doohickey, but I measured voltage drop across f3 and it's only 34mV.

I'm using a 2A power supply, I turned the pi on with only the mouse plugged in and it still froze, I don't think it's a power issue. The voltage between TP1 and TP2 is 4.9Vdc when the pi isn't doing anything, when it's booting up or thinking it's at 4.8. When the usb goes out it goes up to 4.9 - 5, it comes back on for a couple seconds, then it turns back off. Eventually it will go up to 5.1, and that's when you know it gave up, it never comes back on after that.

It seems as though the pi continues to run just fine afterwards, just no usb.

[ags131]

I am unable to check voltages at the moment, but same exact. Hardware and cables pluged into another pi works fine. (Same sd card and everything).

[ags131]

I am still having this issue, Checked voltages last night and the voltages never dropped below 4.8 even with USB SSD plugged in.
I've tried a huge amount of settings and stuff thats been posting in other USB fixes forums, but no luck.
As I said before, I can access serial console if anyone has any ideas, otherwise I will be requesting a replacement. :/

[captainhooyah]

Replace it bro, i got a new one mysteriously delivered to my house last night and it works perfectly. Quit tearing your hair out, iys defective.