linux-kernel - Re: [PATCH 2/2] watchdog: Add Apple SoC watchdog driver

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Message-ID: <ca52e4ee-b5f3-b892-1ba5-7c5656e45fdd@marcan.st>
Date:   Thu, 2 Dec 2021 14:14:21 +0900
From:   Hector Martin <marcan@...can.st>
To:     Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Sven Peter <sven@...npeter.dev>
Cc:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Kettenis <mark.kettenis@...all.nl>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-watchdog@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/2] watchdog: Add Apple SoC watchdog driver

On 14/11/2021 22.18, Alyssa Rosenzweig wrote:
>>>> + * This HW block has three separate watchdogs. WD0 resets the machine
>>>> + * to recovery mode and is not very useful for us. WD1 and WD2 trigger a normal
>>>> + * machine reset. WD0 additionally supports a configurable interrupt.
>>>
>>> Do we have any idea what the difference between WD1 and WD2 is?
>>
>> I've never seen macOS write to WD2 when running in our hypervisor and only
>> found that one when I was looking at the rest of the MMIO region.
>> >From what I can tell it works exactly like WD1.
> 
> Makes sense, thanks.
> 

Are any of these watchdogs active when we boot, and are we leaving them 
like that? I'm pretty sure at least some of the coprocessors have their 
own watchdog (SMC...), which might be one of these. We should make sure 
we don't clobber that.

-- 
Hector Martin (marcan@...can.st)
Public Key: https://mrcn.st/pub