linux-kernel - Re: [PATCH] watchdog: qcom: Start the watchdog in probe

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Message-ID: <cfaaed23-8f59-4447-af0b-b94b35ce68ba@quicinc.com>
Date: Wed, 31 Jan 2024 11:46:44 +0530
From: Pavan Kondeti <quic_pkondeti@...cinc.com>
To: Guenter Roeck <linux@...ck-us.net>
CC: Pavankumar Kondeti <quic_pkondeti@...cinc.com>,
        Bjorn Andersson
	<andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        "Wim Van
 Sebroeck" <wim@...ux-watchdog.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-watchdog@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Mukesh Ojha
	<quic_mojha@...cinc.com>
Subject: Re: [PATCH] watchdog: qcom: Start the watchdog in probe

On Tue, Jan 30, 2024 at 10:01:15PM -0800, Guenter Roeck wrote:
> On 1/30/24 20:15, Pavankumar Kondeti wrote:
> > When CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is enabled, kernel can pet the
> > watchdog until user space takes over. Make use of this feature and
> > start the watchdog in probe.
> > 
> > Signed-off-by: Pavankumar Kondeti <quic_pkondeti@...cinc.com>
> > ---
> >   drivers/watchdog/qcom-wdt.c | 6 +++++-
> >   1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
> > index 9e790f0c2096..4fb5dbf5faee 100644
> > --- a/drivers/watchdog/qcom-wdt.c
> > +++ b/drivers/watchdog/qcom-wdt.c
> > @@ -276,12 +276,16 @@ static int qcom_wdt_probe(struct platform_device *pdev)
> >   	watchdog_init_timeout(&wdt->wdd, 0, dev);
> >   	/*
> > +	 * Kernel can pet the watchdog until user space takes over.
> > +	 * Start the watchdog here to make use of this feature.
> > +	
> 
> No, that is not what CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is about.
> Please see its description.
> 
> NACK.
> 
Thanks for taking a look Guenter. I thought of using
WATCHDOG_HANDLE_BOOT_ENABLED and infiniite open timeout as a hint to start
the watchdog in probe. After seeing your NACK for this patch, I guess 
that would also would have been rejected.

Do you think we can revive this [1] to add support for watchdog pet from
the kernel? It would be helpful in cases where the user space has no
support for watchdog pet (say minimal ramdisk).

[1]
https://lore.kernel.org/linux-watchdog/20210924133509.3454834-1-f.suligoi@asem.it/#t