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

[Heiko Schocher <hs@denx.de>]

Hello Lukasz,

Am 17.03.2015 16:16, schrieb 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@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.

Maybe, I must check this ...

>>>>> 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?

I mean, the code must trigger the WDT somewhere in this while(1).
If not, the WDT resets 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.

Why?

So you can test this behaviour. Do not disable the WDT and start
the dfu command ... the board should reset when you start the dfu
command (without starting dfu-util on the host, and if ctrl() does not
call WATCHDOG_RESET for your hw) ... with my patch it should work ...

BTW: I could not disable the WDT on this board, once it is enabled.
So disabling the WDT is no option ... :-(

> 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?

Yes, because the WDT gets not triggered in this while(1). And maybe
if you start the dfu command with connected cable, but not starting
dfu-util on the host also, but I have not yet running the usb gadget
on this at91 board (at91sam9g20 based) ...

bye,
Heiko
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