[coreboot] USB 2.0 EHCI debug dongle doesn't print logs (at Lenovo G505S)

[Nico Huber]

Hi Ivan,

On 9/28/18 11:50 PM, Ivan Ivanov wrote:
> Thank you for spkmodem comments, now I'm trying out a more reliable
> way - FT232H dongle - to extract the logs from AMD Lenovo G505S. I
> plug it into the correct port - USB 2.0 at laptop's right side.
> However it doesn't print anything except this short test message:
> --- /* Perform a small write. */
> --- ret = dbgp_bulk_write_x(&pipe[DBGP_CONSOLE_EPOUT], "USB\r\n", 5);
> ------ line 322 of ./coreboot/src/drivers/usb/gadget.c
> 
> Thinking that it breaks during the relocation from romstage to
> ramstage (migrate_ehci_debug function at ehci_debug.c ?) , I disabled
> CONFIG_USBDEBUG_IN_ROMSTAGE - but the results are the same: only "USB"
> message. I could see
> --- dprintk(BIOS_INFO, "Test write done\n");
> ------ line 328 of ./coreboot/src/drivers/usb/gadget.c
> at cbmem logs, but even that doesn't get copied to FT232H output.

the purpose of dprintk() here is to only print when EHCI debug is _not_
activated yet. Otherwise the code trying to print something would be
called recursively. But it might actually work at this early point,
with proper configuration (see below).

> 
> Please could you take a look at my coreboot .config and cbmem logs,
> what if this FT232H dongle doesn't get selected as console output for
> some reason? CONFIG_CONSOLE_CBMEM is still enabled, but maybe I should
> disable it?

You are missing CONFIG_CONSOLE_USB.

Nico