linux-kernel - Re: [PATCH v1 4/4] watchdog: npcm: sets card ext1 and ext2 bootstatus during probe

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Message-ID: <998cedf4-82cb-be1b-699f-608ea7a21064@roeck-us.net>
Date:   Sun, 1 Mar 2020 08:10:44 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Tomer Maimon <tmaimon77@...il.com>
Cc:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Joel Stanley <joel@....id.au>,
        Avi Fishman <avifishman70@...il.com>,
        Tali Perry <tali.perry1@...il.com>,
        Nancy Yuen <yuenn@...gle.com>,
        Benjamin Fair <benjaminfair@...gle.com>,
        linux-watchdog@...r.kernel.org,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>
Subject: Re: [PATCH v1 4/4] watchdog: npcm: sets card ext1 and ext2 bootstatus
 during probe

On 3/1/20 8:08 AM, Tomer Maimon wrote:
> Sorry Guenter probebly I didnt explain it well.
> 
> 
> On Sun, 1 Mar 2020 at 12:48, Guenter Roeck <linux@...ck-us.net <mailto:linux@...ck-us.net>> wrote:
> 
>     On 3/1/20 1:40 AM, Tomer Maimon wrote:
>     > During probe NPCM watchdog sets the following bootstatus flags:
>     >       - WDIOF_CARDRESET represent power and core reset.
>     >       - WDIOF_EXTERN1 represent watchdog 0-2 reset.
>     >       - WDIOF_EXTERN2 represent software 1-4 reset.
>     >
>     > Each flag is representing a group of bootstatus.
>     > The user can configure through the device treethe exact reset
>     > to each flag group.
>     >
> 
>     Sorry, this doesn't make sense to me. I could understand reporting
>     the above, but it looks to me like devicetree is used to associate
>     a reset bit from the controller with one of the above.
>     Devicetree only seems to be used to associate reset status bits
>     from the controller with WDIOF_CARDRESET, WDIOF_EXTERN1, or
>     WDIOF_EXTERN2. That adds a lot of complexity for little if any
>     gain. 
> 
>      
> 
>     It would make sense to set the bootstatus bits as suggested above,
>     but that doesn't require devicetree properties.
> 
>     More comments inline.
> 
>     Guenter 
> 
>  
> 
> In the NPCM750 we have the following reset types:
> 
>  1. board reset (Power on reset, Core reset)
>  2. WD reset (0-2 WD reset).
>  3. SW reset (1-4 SW reset).
> 
> 
> Each board can use different reset types, because in the WD status bit there is not enough bits to represent the entire NPCM750 resets.
> 
> The NPCM750 reset groups are represent as follow:
> 
>  - WDIOF_CARDRESET represent power and core reset.
>  - WDIOF_EXTERN1 represent watchdog 0-2 reset.
>  - WDIOF_EXTERN2 represent software 1-4 reset.
> 
Exactly, and I don't see a need to be more specific than that.
This can be implemented without all the DT complexity.

Guenter