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Date:   Fri, 14 Jun 2019 22:33:27 +0200
From:   Alexandre Belloni <>
To:     Ken Sloat <>
Cc:     Guenter Roeck <>,
        "" <>,
        "" <>,
        "" <>,
        "" <>,
        "" <>
Subject: Re: [PATCH v2 1/1] watchdog: atmel: atmel-sama5d4-wdt: Disable
 watchdog on system suspend

On 14/06/2019 18:43:22+0000, Ken Sloat wrote:
> Well I'm a little confused still because there are two separate comments
> in these statements. The first within resume implies that the init should
> be called because we might have lost register values for some reason
> unexplained.

The sama5d2 has a suspend mode where power to the core is completely
cut. Only a few IPs remain powered (in the backup power domain).
Unfortunately, the watchdog is not in that domain and may lose its

> Then within the init it says that the bootloader might have
> modified the registers so we should check them and then update it or
> otherwise disable it. I'm not trying to pick apart the logic or anything, 
> I'm just readily assuming it is good as it was already reviewed before. 

The bootloaders may have started the watchdog (this makes sense if you
really care about reliability) and so we need to be careful to keep the
proper parameters.

> So without digging into that too much, if we don't know if any of the runtime
> situations above might have occurred, then isn't it best to leave my patch
> as is? Yes this has the side effect of resetting the timer count, but if 
> the init call is needed and we don't have any way to know if any
> of the situations occurred, then we have no choice right?

Until we can differentiate between suspend modes, we have no other

Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering

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