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From: Guenter Roeck <linux@roeck-us.net>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>,
	linux-watchdog@vger.kernel.org,
	linux-renesas-soc@vger.kernel.org,
	Geert Uytterhoeven <geert@linux-m68k.org>
Subject: Re: [RFC PATCH] watchdog: renesas_wdt: support handover from bootloader
Date: Fri, 7 Jun 2019 13:41:11 -0700	[thread overview]
Message-ID: <20190607204111.GA19123@roeck-us.net> (raw)
In-Reply-To: <20190524135237.GC15892@kunai>

On Fri, May 24, 2019 at 03:52:37PM +0200, Wolfram Sang wrote:
> On Mon, Apr 15, 2019 at 12:52:01PM +0200, Wolfram Sang wrote:
> > Support an already running watchdog by checking its enable bit and set
> > up the status accordingly before registering the device.
> > 
> > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> 
> After second thought, I am getting confused a little. If the WDT is
> already running then
> 
> a) before this patch: after successful probe, RPM will disable the
> clock until userspace opens the watchdog device
> 
> b) after this patch: during probe, our default timeout will be
> programmed and because of WDOG_HW_RUNNING, the core will generate pings
> until userspace opens the watchdog device.
> 
> So, b) will protect from a crashing kernel (no pings anymore) but not
> from something like missing rootfs, or?
> 
> The usecase I had in mind ("give the kernel <x> seconds to boot into
> working userspace") seems to be achieved by loading the WDT driver as a
> module then, I guess?
> 

Would
https://lore.kernel.org/linux-watchdog/20190605140628.618-1-rasmus.villemoes@prevas.dk/

solve your use case ?

Guenter

  reply	other threads:[~2019-06-07 20:41 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-15 10:52 [RFC PATCH] watchdog: renesas_wdt: support handover from bootloader Wolfram Sang
2019-04-17 18:05 ` Guenter Roeck
2019-04-17 19:01   ` Wolfram Sang
2019-05-09  7:38 ` Geert Uytterhoeven
2019-05-24 13:52 ` Wolfram Sang
2019-06-07 20:41   ` Guenter Roeck [this message]
2019-06-07 20:55     ` Wolfram Sang

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