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From: Guenter Roeck <linux@roeck-us.net>
To: Hans de Goede <hdegoede@redhat.com>,
	Jose Noguera <jnoguera@redhat.com>,
	wim@linux-watchdog.org, linux-watchdog@vger.kernel.org
Cc: Peter Robinson <perobins@redhat.com>
Subject: Re: [Watchdog drivers] - WDIOC_GETSUPPORT clarification
Date: Wed, 18 Aug 2021 07:53:44 -0700	[thread overview]
Message-ID: <3d7ec88a-8756-9a22-9e85-ab3b8c9953d2@roeck-us.net> (raw)
In-Reply-To: <0db70d23-d15c-e485-2600-439dc5d55d47@redhat.com>

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.

Thanks,
Guenter

> Regards,
> 
> Hans
> 


  reply	other threads:[~2021-08-18 14:53 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 [this message]
2021-09-01 11:15       ` Peter Robinson
2021-09-01 19:51         ` Guenter Roeck

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