[coreboot] BeagleBone Black [Master/Slave] Connection

[Haleigh Novak]

​Hello All, 

I am trying to connect a BBB (setup properly for ehci debugging) to a machine that was designed here at my work [well call it '(Cust)' for simplicity] I also have the running 'model' machine [lets call this one '(Orig)'] that the custom one was designed to mimic. I'm hoping that through this email I will reach enough people who have used the BeagleBone Black [BBB] to answer these questions based on the information below the questions. (Forgive me if the question is badly worded, its complicated to explain without visuals - let me know if you need a better explanation.)

0) Is there a way to tell 100% for certain (a query or status of some sort) which device is considered the Master/Host and which device is considered the Slave/Peripheral in a usb connection between two fully functional stand alone machines? 

1) For proper use does the BBB have to be classified as the Master/Host in the usb connection?

2) For proper use does the BBB require the connected machine (the one that ehci debugging info is desired from) to be a Master/Host, or a Slave/Peripheral device, or does it not matter; to allow successful ehci debugging?

[The above questions I have been Goggling, I have not found a strait forward, verified/well explained answer.]

3) The conversion cord I am using I strongly suspect is an OTG, and therefore as it is connected, defines the (Cust) to be the Master/Host - would this cause a 'fight' for Master/Host status that the BBB looses and is as a result classified as a Peripheral/Slave device and rendered non-functional for my needs? [p.s - I know this conversion cord works because I can plug it into (Cust) and on the other end have a peripheral (usb flash, mouse, keyboard - all tested) plugged in and utilize the peripheral without any issue.]

4) If (1) is yes, (2) is doesn't matter or slave/peripheral; is there a way to force the usb to reclassify? Say force (Cust) to be a Slave/Peripheral device and the BBB to be the Master/Host?

The BBB connects to an ehci capable port (for ehci debugging) via a MINI B connector in the BBB and a full sized usb to connect to the debug machine. Now (Orig) has full sized usb ports to which I can connect the BBB directly to and I successfully get the echi debugging information. However (Cust) only has MICRO B connectors - so I have to use a conversion cable on the end of the BBB cable to get the proper size. The ports on the respective 'debug' machines are verified ehci capable ports, both machines have coreboot - exactly the same except for the VGA Device IDs. However (Cust) will not recognize the BBB properly, and sets it up as an ohci device - rendering the BBB virtually useless. Below is the dmesg on both machines of removing and re-inserting the BBB debug cable from the equivalent port.

# DMESG addition on (Orig) after removing and re-inserting the BBB usb into the same port
usb 1-3: USB disconnect, device number 2
usb 1-3: new high speed USB device number 3 using ehci_hcd
usb 1-3: unable to read config index 0 descriptor/start: -32
usb 1-3: chopping to 0 config(s)
usb 1-3: New USB device found, idVendor=0525, idProduct=c0de
usb 1-3: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-3: no configuration chosen from 0 choices

# DMESG addition on (Cust) after removing and re-inserting the BBB usb into the same port
usb 4-1: USB disconnect, device number 2
usb 1-1: new high speed USB device number 6 using ehci_hcd
usb 1-1: device descriptor read/64, error -71
usb 1-1: device descriptor read/64, error -71
usb 1-1: new high speed USB device number 7 using ehci_hcd
usb 1-1: device descriptor read/64, error -71
usb 1-1: device descriptor read/64, error -71
usb 1-1: new high speed USB device number 8 using ehci_hcd
usb 1-1: device not accepting address 8, error -71
usb 1-1: new high speed USB device number 9 using ehci_hcd
usb 1-1: device not accepting address 9, error -71
hub 1-0:1.0: unable to enumerate USB device on port 1
usb 4-1: new full speed USB device number 3 using ohci_hcd
usb 4-1: unable to read config index 0 descriptor/start: -32
usb 4-1: chopping to 0 config(s)
usb 4-1: New USB device found, idVendor=0525, idProduct=c0de
usb 4-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 4-1: no configuration chosen from 0 choices

 Thank you for taking the time to read this. If anyone has any other suggestions as to what might be causing my issue I welcome any thoughts :).

H