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From: Guenter Roeck <linux@roeck-us.net>
To: Peter Robinson <perobins@redhat.com>
Cc: Hans de Goede <hdegoede@redhat.com>,
	Jose Noguera <jnoguera@redhat.com>,
	wim@linux-watchdog.org, linux-watchdog@vger.kernel.org
Subject: Re: [Watchdog drivers] - WDIOC_GETSUPPORT clarification
Date: Wed, 1 Sep 2021 12:51:04 -0700	[thread overview]
Message-ID: <20210901195104.GA1147939@roeck-us.net> (raw)
In-Reply-To: <2c8c29d811c470f1df69ce5bb370f3f493fc55c2.camel@redhat.com>

On Wed, Sep 01, 2021 at 12:15:23PM +0100, Peter Robinson wrote:
> On Wed, 2021-08-18 at 07:53 -0700, Guenter Roeck wrote:
> > On 8/18/21 7:49 AM, Hans de Goede wrote:
> > > Hi,
> > > 
> > > On 8/18/21 4:13 PM, Guenter Roeck wrote:
> > > > On 8/18/21 2:57 AM, Jose Noguera wrote:
> > > > > Hello all!
> > > > > 
> > > > > I’m Jose, working in Red Hat on Fedora IoT and RHEL For Edge
> > > > > related projects.
> > > > > 
> > > > > While trying to add the feature of figuring out whether the
> > > > > current boot was triggered or not by a hardware watchdog using
> > > > > wdctl, we’ve found an odd behaviour in the drivers definition
> > > > > that we would like to check with you.
> > > > > 
> > > > > Looking specifically for the flag WDIOF_CARDRESET, we can find
> > > > > 40 files that contain it:
> > > > > 
> > > > > $ grep -rl CARDRESET drivers/watchdog/ | wc -l
> > > > > 40
> > > > > 
> > > > > but only 19 of them have the flag advertised in the options
> > > > > field of the watchdog_info struct returned by the
> > > > > WDIOC_GETSUPPORT ioctl.
> > > > > 
> > > > > This leads to wdctl not showing WDIOF_CARDRESET for drivers
> > > > > like i6300esb, even when the board had been reset this way:
> > > > > 
> > > > > $ sudo wdctl
> > > > > Device: /dev/watchdog0
> > > > > Identity: i6300ESB timer [version 0]
> > > > > Timeout: 30 seconds
> > > > > Pre-timeout: 0 seconds
> > > > > 
> > > > > FLAG DESCRIPTION STATUS BOOT-STATUS
> > > > > KEEPALIVEPING Keep alive ping reply 1 0
> > > > > MAGICCLOSE Supports magic close char 0 0
> > > > > SETTIMEOUT Set timeout (in seconds) 0 0
> > > > > 
> > > > > Working with Hans (in CC), we added a little patch (BugZilla
> > > > > ticket: 1993983) on wdctl and this would be the output of the
> > > > > command when it was a card reset triggered boot:
> > > > > 
> > > > > $ sudo wdctl
> > > > > Device: /dev/watchdog0
> > > > > Identity: i6300ESB timer [version 0]
> > > > > Thank you all for your time,
> > > > > 
> > > > > Jose
> > > > 
> > > > > Timeout: 30 seconds
> > > > > Pre-timeout: 0 seconds
> > > > > 
> > > > > FLAG DESCRIPTION STATUS BOOT-STATUS
> > > > > CARDRESET Card previously reset the CPU 1 1
> > > > > KEEPALIVEPING Keep alive ping reply 1 0
> > > > > MAGICCLOSE Supports magic close char 0 0
> > > > > SETTIMEOUT Set timeout (in seconds) 0 0
> > > > > 
> > > > > So our question is, may we know what is intended to be present
> > > > > in ident.options? What should the API call WDIOC_GETSUPPORT
> > > > > return in the options field?
> > > > > 
> > > > 
> > > > Search for WDIOC_GETSUPPORT in Documentation/watchdog/watchdog-
> > > > api.rst.
> > > > I don't see any ambiguity there. Patches welcome.
> > > 
> > > Ok, so drivers which may set CARDRESET in their GETBOOTSTATUS
> > > reply, but
> > > don't advertise this in their GETSUPPORT watchdog_info.options
> > > reply
> > > are buggy and should be fixed, got it. Thanks.
> > > 
> > > I've made a note about fixing this in a possible-kernel-projects
> > > document
> > > which I keep for when people who are interested in kernel
> > > development
> > > ask me for projects.
> > > 
> > 
> > With an add-on: If the driver in question is an old-style driver,
> > anyone
> > affected by the problem should really convert the driver to support
> > the watchdog subsystem.
> 
> Would you have a link to any docs/posts outlining what needs to be done
> for conversion to the watchdog subsystem?

Documentation/watchdog/convert_drivers_to_kernel_api.rst should help.

Guenter

      reply	other threads:[~2021-09-01 19:51 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CAKu6O181WOq36RCDO0VPcsZZoUFAJ88BMqv0Hqf+qYCeZsMJtQ@mail.gmail.com>
2021-08-18 12:53 ` Hans de Goede
2021-08-18 14:13 ` Guenter Roeck
2021-08-18 14:49   ` Hans de Goede
2021-08-18 14:53     ` Guenter Roeck
2021-09-01 11:15       ` Peter Robinson
2021-09-01 19:51         ` Guenter Roeck [this message]

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