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

[Heiko Schocher]

Hello Lukasz,

Am 18.03.2015 08:44, schrieb Lukasz Majewski:
> Hi Heiko,
>
>> 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 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.
>>
>> 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 ... :-(
>
> Ok, I see. Then I will apply the proposed patch.

great!

>>> 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) ...
>
> Thanks for explanation. I just wanted to have bigger picture of the
> problem.

all right.

bye,
Heiko
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