linux-kernel - Re: [PATCH] selftests: watchdog: Add optional file argument

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Date:   Thu, 29 Aug 2019 17:28:52 +0200
From:   Eugeniu Rosca <erosca@...adit-jv.com>
To:     "George G. Davis" <george_davis@...tor.com>
CC:     Shuah Khan <shuah@...nel.org>,
        Jerry Hoemann <jerry.hoemann@....com>,
        Colin Ian King <colin.king@...onical.com>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Eugeniu Rosca <erosca@...adit-jv.com>,
        Eugeniu Rosca <roscaeugeniu@...il.com>
Subject: Re: [PATCH] selftests: watchdog: Add optional file argument

On Thu, Aug 29, 2019 at 04:38:14PM +0200, Eugeniu Rosca wrote:
> Hi George,
> 
> On Thu, Aug 29, 2019 at 12:39:25AM -0400, George G. Davis wrote:
> > Some systems have multiple watchdog devices where the first device
> > registered is assigned to the /dev/watchdog device file.
> 
> Confirmed on R-Car H3-Salvator-X:
> 
> root@...r-gen3:~# ls -al /dev/watchdog*
> crw-------    1 root     root       10, 130 Aug 21 09:38 /dev/watchdog
> crw-------    1 root     root      247,   0 Aug 21 09:38 /dev/watchdog0

Based on [1], I think this patch is actually helpful when there
is at least a /dev/watchdog1 in the system. Particularly on R-Car3,
this happens when enabling softdog in addition to the standard RWDT:

root@...r-gen3:~# ls -al /dev/watchdog*
crw-------    1 root     root       10, 130 Aug 21 09:38 /dev/watchdog
crw-------    1 root     root      247,   0 Aug 21 09:38 /dev/watchdog0
crw-------    1 root     root      247,   1 Aug 21 09:38 /dev/watchdog1

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/watchdog/watchdog-kernel-api.rst?h=v5.3-rc6#n71
  ----8<----
id 0 is special. It has both a
/dev/watchdog0 cdev (dynamic major, minor 0) as well as the old
/dev/watchdog miscdev.
  ----8<----

-- 
Best Regards,
Eugeniu.