[U-Boot] [PATCH] dfu: cmd: trigger watchdog before calling usb_gadget_handle_interrupts

[Lukasz Majewski]

Hi Heiko,

> Hello Lukasz,
> 
> Am 17.03.2015 13:56, schrieb Lukasz Majewski:
> > Hi Heiko,
> >
> >> Hello Lukasz,
> >>
> >> Am 17.03.2015 10:52, schrieb Lukasz Majewski:
> >>> Hi Heiko,
> >>>
> >>>> trigger watchdog before calling usb_gadget_handle_interrupts()
> >>>> This prevents board resets when calling dfu command on boards
> >>>> which have a watchdog.
> >>>>
> >>>> Signed-off-by: Heiko Schocher <hs at denx.de>
> >>>> ---
> >>>>
> >>>>    common/cmd_dfu.c | 2 ++
> >>>>    1 file changed, 2 insertions(+)
> >>>>
> >>>> diff --git a/common/cmd_dfu.c b/common/cmd_dfu.c
> >>>> index e975abe..46af4cf 100644
> >>>> --- a/common/cmd_dfu.c
> >>>> +++ b/common/cmd_dfu.c
> >>>> @@ -9,6 +9,7 @@
> >>>>     */
> >>>>
> >>>>    #include <common.h>
> >>>> +#include <watchdog.h>
> >>>>    #include <dfu.h>
> >>>>    #include <g_dnl.h>
> >>>>    #include <usb.h>
> >>>> @@ -64,6 +65,7 @@ static int do_dfu(cmd_tbl_t *cmdtp, int flag,
> >>>> int argc, char * const argv[]) if (ctrlc())
> >>>>    			goto exit;
> >>>>
> >>>> +		WATCHDOG_RESET();
> >>>>    		usb_gadget_handle_interrupts();
> >>>>    	}
> >>>>    exit:
> >>>
> >>> It seems strange for me, that we must reset watchdog when looping
> >>> in the dfu.
> >>
> >> Hmm.. maybe I overlook something, but If you look into this
> >> while(1) loop, there is no trigger of the watchdog ... and if I
> >> start the dfu command without a USB cable on the board, what
> >> triggers the boards watchdog?
> >
> > So the problem is when cable is not attached to the board and you
> > call dfu command to execute?
> 
> Yes.

For UMS gadget there is defined g_dnl_board_usb_cable_connected()
function.

However, it is not yet supported in dfu and requires working MUIC
block, which might be not available at your board.

> 
> >>> What is the WATCHDOG interval on the affected board?
> >>
> >> ~5 seconds
> >>
> >> Ah, this is on an at91 board .. and in the
> >> drivers/serial/atmel_usart.c atmel_serial_tstc() is no
> >> WATCHDOG_RESET...
> >>
> >> So ctrlc() does not trigger the watchdog
> >
> > Could you be a bit more specific here. Does your board expect
> > ctrlc() to update watchdog, so it won't reset?
> 
> I do not know, if ctrlc() must trigger the WDT ... I just looked into
> the while(1) loop in common/cmd_dfu.c. There is only ctrlc() which
> could trigger the WDT... and on at91 it does not trigger it ...

By trigger you mean reset WDT core and don't reset the board?

> 
> If dfu transfer is started there is some output on the console, which
> triggers the WDT too ... do you have a board with a running WDT?

On trats/trats2 we disable WDT when we enter the u-boot.

I can imagine following situation when WDT is enabled when u-boot
starts (its timeout is ~5sec) and then you start dfu transfer with not
connected cable.
Then 5sec pass since cable is not connected and no transfer is ongoing.
This causes board reset by WDT.

Am I right?

> 
> bye,
> Heiko



-- 
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group