[U-Boot] [PATCH 3/3] dt: bcm63158: watchdog should use a 50Mhz clock

[Stefan Roese]

Hi Philippe,

On 06.05.19 14:38, Philippe REYNES wrote:
> Hi Stefan,
> 
>> On 03.05.19 19:43, Philippe Reynes wrote:
>>> The watchdog should use a clock at 50 Mhz, so
>>> instead of using the clock osc (200 Mhz), we
>>> define a reference clock at 50Mhz and use it
>>> for both watchdog.
>>>
>>> Signed-off-by: Philippe Reynes <philippe.reynes at softathome.com>
>>
>> Just curious: Why is this the case? Is this also what's done in
>> the Linux DT version?
> 
>  From my understanding, in the linux kernel, the driver doesn't compute
> the timeout for the watchdog counter register. Every second, the driver
> set the maximum value in the watchdog counter register and compute a
> logical tick. If this tick decrease below zero, the watchdog isn't
> restarted, so when the watchdog counter reach zero,  the board is resetted.
> 
> In u-boot, the driver compute the expected timeout and set it
> in the watchdog register.

I see. But why "should the watchdog use a clock at 50MHz" instead of
the default 200MHz (from your commit text)?

I'm checking as this change most likely results in a DT difference in
the U-Boot vs the Linux version, which should be avoided.

Thanks,
Stefan