[PATCH] board: mediatek: disable watchdog on BananaPi R2

Matthias Brugger mbrugger at suse.com
Mon Jan 11 16:44:53 CET 2021 


On 11/01/2021 09:57, Heinrich Schuchardt wrote:
> On 11.01.21 08:48, Stefan Roese wrote:
>>
>>
>> On 11.01.21 08:17, Heinrich Schuchardt wrote:
>>> Am 11. Januar 2021 08:02:12 MEZ schrieb Stefan Roese <sr at denx.de>:
>>>> Added Heinrich to Cc.
>>>>
>>>> On 10.01.21 19:44, Matthias Brugger wrote:
>>>>> On 09/01/2021 15:57, Stefan Roese wrote:
>>>>>> On 09.01.21 03:32, Matthias Brugger wrote:
>>>>>>> On 08/01/2021 08:39, Stefan Roese wrote:
>>>>>>>> On 07.01.21 16:36, matthias.bgg at kernel.org wrote:
>>>>>>>>> From: Matthias Brugger <mbrugger at suse.com>
>>>>>>>>>
>>>>>>>>> Watchdog timeout comes in before we are able to load the
>>>>>>>>> kernel and reset the watchdog. Disable the watchdog late in the
>>>> boot
>>>>>>>>> process to be able to boot the board.
>>>>>>>>
>>>>>>>> Can't you change the WDT reset timeout instead to a higher value?
>>>>>>>>
>>>>>>>
>>>>>>> I tried that, but the HW has a max timeout of 15984 ms.
>>>> Unfortunately that's not
>>>>>>> enough.
>>>>>>
>>>>>> Nearly 16 seconds is not enough to boot into Linux so that the Linux
>>>>>> watchdog daemon can take control?
>>>>>>
>>>>>
>>>>> Exactly. I'm using a standard distro image. I think the main problem
>>>> is, that it
>>>>> needs 14 seconds for the EFI stub to actually boot the kernel.
> 
> Hello Matthias,

Hi Heinrich :)

> 
> I observed that on some recent version Linux before 5.10 booting seemed
> to be delayed by dozens of seconds on many boards. On which Linux
> version did you see the problem?
> 

I think it started on 5.9 or 5.10. Right now I'm seeing it with 5.10 and 5.11-rc2.

>>>>
>>>> I've not much experience (yet) with the "EFI stub". But if it takes
>>>> this
>>>> long, wouldn't it make sense that this stub also supports the WDT?
>>>
>>> efi_timer_check() calls WATCHDOG_RESET() trying to avoid that the
>>> hardware watchdog is triggered.
>>
>> So efi_timer_check() is called quite frequently and should be enough
>> to reset the U-Boot WDT while residing in EFI? Not sure, why the reset
>> occurs in Matthias's case then.
> 
> efi_timer_check() is only invoked, if the UEFI API is invoked.
> Especially if the problem occurs after ExitBootServices() it is not
> called anymore.
> 
>>
>>> There is a software watchdog
>>> defaulting to 5 minutes in efi_watchdog.c which can be modified
>>> via the EFI API.
>>>
>>> Is there a U-Boot API to disable the hardware watchdog?
>>
>> Yes:
>>
>> /*
>>  * Stop the timer, thus disabling the Watchdog. Use wdt_start to start
>> it again.
>>  *
>>  * @dev: WDT Device
>>  * @return: 0 if OK, -ve on error
>>  */
>> int wdt_stop(struct udevice *dev);
> 
> It would be interesting to understand if your problem occurs before or
> after efi_exit_boot_services() is called. You could you add printf()
> statements after EFI_ENTRY() and before EFI_EXIT() to see if it is reached.
> 

It happens after EFI_EXIT():
[2021-01-11 14:06:04.621] EFI stub: Booting Linux Kernel...
[2021-01-11 14:06:04.624] EFI stub: Using DTB from configuration table
[2021-01-11 14:06:04.628] EFI stub: Exiting boot services and installing virtual
address map...
[2021-01-11 14:06:04.637] efi_exit_boot_services EFI_ENTRY
[2021-01-11 14:06:04.641] efi_exit_boot_services EFI_EXIT
[2021-01-11 14:06:20.972]
[2021-01-11 14:06:20.973] [USBD] USB PRB0 LineState: 40

So reboot after around 16 seconds.

> Could you further, please, test if adding wdt_stop() to the start of
> do_bootefi() in cmd/bootefi.c solves your problem.

Yes, that works. Do you want me to disable watchdog for all EFI boot cases?

Regards,
Matthias

> 
> Best regards
> 
> Heinrich
> 
>>
>> Thanks,
>> Stefan
>>
>>> Best regards
>>>
>>> Heinrich
>>>
>>>
>>>>
>>>> Thanks,
>>>> Stefan
>>>>
>>>>> I've already the
>>>>> watchdog timer as build-in (which is not the best to do, taking into
>>>> account
>>>>> that we don't want to bloat our distro kernel with random board
>>>> specific drivers
>>>>> build-in. If we I had the watchdog driver as kernel module it would
>>>> take forever
>>>>> to get that loaded.
>>>>>
>>>>> You can find a serial log with timestamp from the moment U-Boot got
>>>> loaded until
>>>>> the kernel actually boots here:
>>>>> https://paste.opensuse.org/98390849
>>>>>
>>>>> Regards,
>>>>> Matthias
>>>>>
>>>>>> Thanks,
>>>>>> Stefan
>>>>>>
>>>>>>> Regards,
>>>>>>> Matthias
>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Stefan
>>>>>>>>
>>>>>>>>> Signed-off-by: Matthias Brugger <mbrugger at suse.com>
>>>>>>>>>
>>>>>>>>> ---
>>>>>>>>>
>>>>>>>>>      board/mediatek/mt7623/mt7623_rfb.c | 8 ++++++++
>>>>>>>>>      configs/mt7623n_bpir2_defconfig    | 1 +
>>>>>>>>>      2 files changed, 9 insertions(+)
>>>>>>>>>
>>>>>>>>> diff --git a/board/mediatek/mt7623/mt7623_rfb.c
>>>>>>>>> b/board/mediatek/mt7623/mt7623_rfb.c
>>>>>>>>> index 984e75ccaf..22120be412 100644
>>>>>>>>> --- a/board/mediatek/mt7623/mt7623_rfb.c
>>>>>>>>> +++ b/board/mediatek/mt7623/mt7623_rfb.c
>>>>>>>>> @@ -5,6 +5,7 @@
>>>>>>>>>        #include <common.h>
>>>>>>>>>      #include <mmc.h>
>>>>>>>>> +#include <watchdog.h>
>>>>>>>>>        DECLARE_GLOBAL_DATA_PTR;
>>>>>>>>>      @@ -40,3 +41,10 @@ int mmc_get_env_dev(void)
>>>>>>>>>          return mmc_get_boot_dev();
>>>>>>>>>      }
>>>>>>>>>      #endif
>>>>>>>>> +
>>>>>>>>> +#ifdef CONFIG_BOARD_LATE_INIT
>>>>>>>>> +int board_late_init(void)
>>>>>>>>> +{
>>>>>>>>> +    wdt_stop(gd->watchdog_dev);
>>>>>>>>> +}
>>>>>>>>> +#endif
>>>>>>>>> diff --git a/configs/mt7623n_bpir2_defconfig
>>>> b/configs/mt7623n_bpir2_defconfig
>>>>>>>>> index 9177c17dff..fe0b6259dd 100644
>>>>>>>>> --- a/configs/mt7623n_bpir2_defconfig
>>>>>>>>> +++ b/configs/mt7623n_bpir2_defconfig
>>>>>>>>> @@ -14,6 +14,7 @@ CONFIG_FIT_VERBOSE=y
>>>>>>>>>      CONFIG_BOOTDELAY=3
>>>>>>>>>      CONFIG_SYS_CONSOLE_IS_IN_ENV=y
>>>>>>>>>      CONFIG_DEFAULT_FDT_FILE="mt7623n-bananapi-bpi-r2.dtb"
>>>>>>>>> +CONFIG_BOARD_LATE_INIT=y
>>>>>>>>>      # CONFIG_DISPLAY_BOARDINFO is not set
>>>>>>>>>      CONFIG_SYS_PROMPT="U-Boot> "
>>>>>>>>>      CONFIG_CMD_BOOTMENU=y
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Viele Grüße,
>>>>>>>> Stefan
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> Viele Grüße,
>>>>>> Stefan
>>>>>>
>>>>>
>>>>
>>>>
>>>> Viele Grüße,
>>>> Stefan
>>>
>>
>>
>> Viele Grüße,
>> Stefan
>>
>

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