MSP430 failed to response Get Device Descriptor

[hathach]

Operating System

Linux

Board

msp_exp430f5529lp

Firmware

examples/device/cdc_msc

What happened ?

Failed to enumerate on both Linux and Windows. The root cause is msp430 responses with incorrect data, basically using the control request instead of the device descriptor payload.

How to reproduce ?

1. Run cdc_msc
2. PC will complain with read device descriptor error

[89841.141609] usb 3-2.1: new full-speed USB device number 45 using xhci_hcd
[89846.329389] usb 3-2.1: device descriptor read/64, error 8

Debug Log

After 3 attempts, host issue bus reset and it loops over

USBD init
CDC init
MSC init
USBD Bus Reset : Full Speed

USBD Setup Received 80 06 00 01 00 00 40 00 
  Get Descriptor Device
  Queue EP 80 with 8 bytes ...
USBD Xfer Complete on EP 80 with 8 bytes
  Queue EP 00 with 0 bytes ...
USBD Xfer Complete on EP 00 with 0 bytes

USBD Setup Received 80 06 00 01 00 00 40 00 
  Get Descriptor Device
  Queue EP 80 with 8 bytes ...
USBD Xfer Complete on EP 80 with 8 bytes
  Queue EP 00 with 0 bytes ...
USBD Xfer Complete on EP 00 with 0 bytes

USBD Setup Received 80 06 00 01 00 00 40 00 
  Get Descriptor Device
  Queue EP 80 with 8 bytes ...
USBD Xfer Complete on EP 80 with 8 bytes
  Queue EP 00 with 0 bytes ...
USBD Xfer Complete on EP 00 with 0 bytes
USBD Bus Reset : Full Speed

Screenshots

screenshot where 8 bytes DATA is same with setup request (with wlength changed from 64 to 8 bytes).

[hathach]

It is probably buffer overflow and/or mis-management somewhere. Could try to do some checkout and bisect to narrow down the changes.

[cr1901]

@hathach Would you be willing to handle this for me? If not, I'll take a look in the coming days.

Is that screenshot first transaction that happens after bus reset (i.e. beginning of enumeration)? If so, that looks somewhat (see italics) normal to me.

MSP430 is hardcoded for control endpoint to xfer 8 bytes at a time. I know the first xfer an OS will send should be 64 bytes, and the OS should notice that the MSP430 only responded w/ 8 bytes. MSP430 responding by echoing the setup packet is incorrect, but I don't understand why that particular transaction should fail. I would expect the OS to ignore the device payload, and then set the EP0 packet size appropriately.

I would then expect subsequent SETUPs to fail because of what you describe:

The root cause is msp430 responses with incorrect data, basically using the control request instead of the device descriptor payload.

[hathach]

@cr1901 no worries, I will try to fix this whenever I got time (currently I am focusing on esp32 work). This issue is discovered when testing #1102 (for ref #1096 (comment)) , and is reminder for me since I have a bad memory :)

dcd msp430 isn’t modified for a while. It is probably recent changes since it work flawlessly previously.