linux-kernel - Re: [PATCH 0/3] Suspending i.MX watchdog in WAIT mode

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Message-ID: <d57f34db-2aff-f469-0146-335950c2b437@norik.com>
Date:   Thu, 20 Oct 2022 07:21:59 +0200
From:   Andrej Picej <andrej.picej@...ik.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     linux-watchdog@...r.kernel.org, shawnguo@...nel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-imx@....com, festevam@...il.com,
        kernel@...gutronix.de, s.hauer@...gutronix.de,
        wim@...ux-watchdog.org, robh+dt@...nel.org
Subject: Re: [PATCH 0/3] Suspending i.MX watchdog in WAIT mode

Hi Guenter,

On 19. 10. 22 17:30, Guenter Roeck wrote:
> On Wed, Oct 19, 2022 at 01:17:11PM +0200, Andrej Picej wrote:
>> The i.MX6 watchdog can't be stopped once started. This means that
>> special hardware suspend needs to be configured when the device enters
>> low-power modes.
>> Usually i.MX devices have two bits which deal with this:
>> - WDZST bit disables the timer in "deeper" low power modes and
>> - WDW bit disables the timer in "WAIT" mode which corresponds with
>> Linux's "freeze" low-power mode.
>>
>> WDZST bit support is already in place since 1a9c5efa576e ("watchdog: imx2_wdt: disable watchdog timer during low power mode").
>> WDW bit is not common for all imx2-wdt supported devices, therefore use
>> a new device-tree property "fsl,suspend-in-wait" which suspends the
>> watchdog in "WAIT" mode.
> 
> I think that needs to be validated using the "compatible" property;
> it should not be possible to set/accept the new flag for devices
> which don't support it.

Ok, I can add that to a v2.

Thanks,
Andrej

> 
> Thanks,
> Guenter
>