[U-Boot] USB works (or not) depending on SYS_BOOT (with TPS65920)

[Orjan Friberg <of@flatfrog.com>]

Hi,

I'm seeing some weird behaviour with host mode USB on the OTG port in 
u-boot (2011.03), and just wondering if anyone else seen this.

Booting from NAND after a power cycle, host mode USB doesn't work (the 
'usb reset' command times out).

However, if I change the boot order (external button) to go through USB 
and UART before NAND it does work (it enters host mode, and devices are 
discovered).

After that, USB continues to work after warm-resetting the board.  It's 
not until after a cold reset/power cycle that it stops working again.


It seems the boot rom must be doing some initialization of the USB phy 
(this is with a TPS65920).  Dumping the I2C regs of the USB phy in 
u-boot shows a lot of differences between the two boot modes.

This is on a custom board, BeagleBoard derived but with a 3730.


Any ideas?

Thanks,
Orjan

-- 
Orjan Friberg
FlatFrog Laboratories AB