linux-kernel - Re: [PATCH v3 3/4] watchdog: simatic-ipc-wdt: add new driver for Siemens Industrial PCs

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Message-ID: <e36d8b9f-42a1-0d8c-a4cc-f497acd155fe@roeck-us.net>
Date:   Wed, 7 Apr 2021 05:17:12 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Henning Schild <henning.schild@...mens.com>
Cc:     "Enrico Weigelt, metux IT consult" <lkml@...ux.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux LED Subsystem <linux-leds@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        linux-watchdog@...r.kernel.org,
        Srikanth Krishnakar <skrishnakar@...il.com>,
        Jan Kiszka <jan.kiszka@...mens.com>,
        Gerd Haeussler <gerd.haeussler.ext@...mens.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Mark Gross <mgross@...ux.intel.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Pavel Machek <pavel@....cz>
Subject: Re: [PATCH v3 3/4] watchdog: simatic-ipc-wdt: add new driver for
 Siemens Industrial PCs

On 4/7/21 1:53 AM, Andy Shevchenko wrote:
> On Tue, Apr 6, 2021 at 5:56 PM Henning Schild
> <henning.schild@...mens.com> wrote:
>>
>> Am Thu, 1 Apr 2021 18:15:41 +0200
>> schrieb "Enrico Weigelt, metux IT consult" <lkml@...ux.net>:
>>
>>> On 29.03.21 19:49, Henning Schild wrote:
>>>
>>> Hi,
>>>
>>>> This driver adds initial support for several devices from Siemens.
>>>> It is based on a platform driver introduced in an earlier commit.
>>>
>>> Where does the wdt actually come from ?
>>>
>>> Is it in the SoC ? (which SoC exactly). SoC-builtin wdt is a pretty
>>> usual case.
>>>
>>> Or some external chip ?
>>
>> I guess external chip, but again we are talking about multiple
>> machines. And the manuals i read so far do not go into that sort of
>> detail. In fact on some of the machines you will have two watchdogs,
>> one from the SoC and that "special" one.
>> That has several reasons, probably not too important here. The HW guys
>> are adding another wd not just for fun, and it would be nice to have a
>> driver.
>>
>>> The code smells a bit like two entirely different wdt's that just have
>>> some similarities. If that's the case, I'd rather split it into two
>>> separate drivers and let the parent driver (board file) instantiate
>>> the correct one.
>>
>> Yes, it is two. Just like for the LEDs. One version PIO-based another
>> version gpio/p2sb/mmio based.
> 
> I tend to agree with Enrico that this should be two separate drivers.
> 

Agreed.

Guenter

>> In fact the latter should very likely be based on that gpio pinctl,
>> whether it really needs to be a separate driver will have to be seen.
>> There are probably pros and cons for both options.
> 
>