From: Simon Arlott <simon@fire.lp0.eu> To: Guenter Roeck <linux@roeck-us.net>, linux-watchdog@vger.kernel.org Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, Ralf Baechle <ralf@linux-mips.org>, Thomas Gleixner <tglx@linutronix.de>, Jason Cooper <jason@lakedaemon.net>, Marc Zyngier <marc.zyngier@arm.com>, Kevin Cernekee <cernekee@gmail.com>, Florian Fainelli <f.fainelli@gmail.com>, Wim Van Sebroeck <wim@iguana.be>, Maxime Bizon <mbizon@freebox.fr>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, linux-mips@linux-mips.org, Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>, Mark Rutland <mark.rutland@arm.com>, Ian Campbell <ijc+devicetree@hellion.org.uk>, Kumar Gala <galak@codeaurora.org>, Jonas Gorski <jogo@openwrt.org> Subject: Re: [PATCH (v2) 7/10] watchdog: bcm63xx_wdt: Add get_timeleft function Date: Wed, 25 Nov 2015 08:17:08 +0000 [thread overview] Message-ID: <56556E84.50202@simon.arlott.org.uk> (raw) In-Reply-To: <56552214.2050808@roeck-us.net> On 25/11/15 02:51, Guenter Roeck wrote: > On 11/24/2015 02:15 PM, Simon Arlott wrote: >> Return the remaining time from the hardware control register. >> >> Warn when the device is registered if the hardware watchdog is currently >> running and report the remaining time left. > > This is really two logical changes, isn't it ? If you insist then I'll split it out into yet another patch. > Nice trick to figure out if the watchdog is running. > > What is the impact ? Will this result in interrupts ? Yes, if it is running it will receive interrupts and check hw->running to determine if it should stop the watchdog or not. > If so, would it make sense to _not_ reset the system after a timeout > in this case, but to keep pinging the watchdog while the watchdog device > is not open ? As the whole point of a hardware watchdog is to reset the system when there is a problem with the software, it should not be automatically reset by the driver on startup. If the watchdog is already running then it needs to be pinged by userspace before the timeout. The bootloader (CFE) doesn't leave the watchdog running. On my system I prepend some code before vmlinuz that starts it running at the maximum timeout. A module parameter could be added to automatically ping/stop it if it's running, but this should be in the watchdog core and not an individual driver. -- Simon Arlott
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From: Simon Arlott <simon-A6De1vDTPLDsq35pWSNszA@public.gmane.org> To: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>, linux-watchdog-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Ralf Baechle <ralf-6z/3iImG2C8G8FEW9MqTrA@public.gmane.org>, Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, Jason Cooper <jason-NLaQJdtUoK4Be96aLqz0jA@public.gmane.org>, Marc Zyngier <marc.zyngier-5wv7dgnIgG8@public.gmane.org>, Kevin Cernekee <cernekee-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Florian Fainelli <f.fainelli-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Wim Van Sebroeck <wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org>, Maxime Bizon <mbizon-MmRyKUhfbQ9GWvitb5QawA@public.gmane.org>, Linux Kernel Mailing List <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, linux-mips-6z/3iImG2C8G8FEW9MqTrA@public.gmane.org, Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>, Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>, Ian Campbell <ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org>, Kumar Gala <galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>, Jonas Gorski <jogo-p3rKhJxN3npAfugRpC6u6w@public.gmane.org> Subject: Re: [PATCH (v2) 7/10] watchdog: bcm63xx_wdt: Add get_timeleft function Date: Wed, 25 Nov 2015 08:17:08 +0000 [thread overview] Message-ID: <56556E84.50202@simon.arlott.org.uk> (raw) In-Reply-To: <56552214.2050808-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org> On 25/11/15 02:51, Guenter Roeck wrote: > On 11/24/2015 02:15 PM, Simon Arlott wrote: >> Return the remaining time from the hardware control register. >> >> Warn when the device is registered if the hardware watchdog is currently >> running and report the remaining time left. > > This is really two logical changes, isn't it ? If you insist then I'll split it out into yet another patch. > Nice trick to figure out if the watchdog is running. > > What is the impact ? Will this result in interrupts ? Yes, if it is running it will receive interrupts and check hw->running to determine if it should stop the watchdog or not. > If so, would it make sense to _not_ reset the system after a timeout > in this case, but to keep pinging the watchdog while the watchdog device > is not open ? As the whole point of a hardware watchdog is to reset the system when there is a problem with the software, it should not be automatically reset by the driver on startup. If the watchdog is already running then it needs to be pinged by userspace before the timeout. The bootloader (CFE) doesn't leave the watchdog running. On my system I prepend some code before vmlinuz that starts it running at the maximum timeout. A module parameter could be added to automatically ping/stop it if it's running, but this should be in the watchdog core and not an individual driver. -- Simon Arlott -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2015-11-25 8:17 UTC|newest] Thread overview: 95+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-11-21 19:02 [PATCH 1/4] clocksource: Add brcm,bcm6345-timer device tree binding Simon Arlott 2015-11-21 19:02 ` Simon Arlott 2015-11-21 19:03 ` [PATCH 2/4] MIPS: bmips: Add bcm6345-l2-timer interrupt controller Simon Arlott 2015-11-21 19:04 ` [PATCH 3/4] watchdog: Add brcm,bcm6345-wdt device tree binding Simon Arlott 2015-11-22 22:13 ` Rob Herring 2015-11-22 22:13 ` Rob Herring 2015-11-21 19:05 ` [PATCH 4/4] MIPS: bmips: Convert bcm63xx_wdt to use WATCHDOG_CORE Simon Arlott 2015-11-21 19:05 ` Simon Arlott 2015-11-21 21:32 ` Guenter Roeck 2015-11-21 21:44 ` Simon Arlott 2015-11-21 21:44 ` Simon Arlott 2015-11-22 2:32 ` Guenter Roeck 2015-11-22 14:02 ` [PATCH 4/10] (Was: [PATCH 4/4]) " Simon Arlott 2015-11-22 14:05 ` [PATCH 4/10] watchdog: bcm63xx_wdt: Handle hardware interrupt and remove software timer Simon Arlott 2015-11-24 18:21 ` Guenter Roeck 2015-11-24 18:21 ` Guenter Roeck 2015-11-24 18:21 ` Guenter Roeck 2015-11-25 20:14 ` Jonas Gorski 2015-11-25 20:14 ` Jonas Gorski 2015-11-25 20:28 ` Simon Arlott 2015-11-25 20:28 ` Simon Arlott 2015-11-25 22:33 ` [PATCH (v2) " Simon Arlott 2015-11-25 22:33 ` Simon Arlott 2015-11-22 14:06 ` [PATCH 5/10] watchdog: bcm63xx_wdt: Use WATCHDOG_CORE Simon Arlott 2015-11-22 14:06 ` Simon Arlott 2015-11-25 2:44 ` Guenter Roeck 2015-11-25 2:44 ` Guenter Roeck 2015-11-25 13:02 ` Simon Arlott 2015-11-25 14:10 ` Guenter Roeck 2015-11-25 14:10 ` Guenter Roeck 2015-11-25 19:43 ` Simon Arlott 2015-11-25 19:43 ` Simon Arlott 2015-11-25 22:40 ` [PATCH (v3) 5/11] " Simon Arlott 2015-11-25 22:40 ` Simon Arlott 2015-11-22 14:07 ` [PATCH 6/10] watchdog: bcm63xx_wdt: Obtain watchdog clock HZ from "periph" clk Simon Arlott 2015-11-22 14:07 ` Simon Arlott 2015-11-23 15:02 ` Jonas Gorski 2015-11-23 15:02 ` Jonas Gorski 2015-11-23 18:19 ` Florian Fainelli 2015-11-23 18:19 ` Florian Fainelli 2015-11-23 19:00 ` Simon Arlott 2015-11-23 19:00 ` Simon Arlott 2015-11-24 22:12 ` [PATCH (v2) " Simon Arlott 2015-11-24 22:42 ` Florian Fainelli 2015-11-24 22:42 ` Florian Fainelli 2015-11-25 22:47 ` [PATCH (v3) 6/11] " Simon Arlott 2015-11-25 22:47 ` Simon Arlott 2015-11-22 14:09 ` [PATCH 7/10] watchdog: bcm63xx_wdt: Add get_timeleft function Simon Arlott 2015-11-22 14:09 ` Simon Arlott 2015-11-24 22:15 ` [PATCH (v2) " Simon Arlott 2015-11-24 22:15 ` Simon Arlott 2015-11-24 22:43 ` Florian Fainelli 2015-11-24 22:43 ` Florian Fainelli 2015-11-25 2:51 ` Guenter Roeck 2015-11-25 2:51 ` Guenter Roeck 2015-11-25 8:17 ` Simon Arlott [this message] 2015-11-25 8:17 ` Simon Arlott 2015-11-25 22:50 ` [PATCH (v3) 7/11] " Simon Arlott 2015-11-25 22:50 ` Simon Arlott 2015-11-25 22:54 ` [PATCH (v4) " Simon Arlott 2015-11-25 22:54 ` Simon Arlott 2015-11-25 22:57 ` [PATCH (v4) 8/11] watchdog: bcm63xx_wdt: Warn if the watchdog is currently running Simon Arlott 2015-11-25 22:57 ` Simon Arlott 2015-11-22 14:11 ` [PATCH 8/10] watchdog: bcm63xx_wdt: Remove dependency on mach-bcm63xx functions/defines Simon Arlott 2015-11-22 14:11 ` Simon Arlott 2015-11-22 14:12 ` [PATCH 9/10] watchdog: bcm63xx_wdt: Use bcm63xx_timer interrupt directly Simon Arlott 2015-11-22 14:12 ` Simon Arlott 2015-11-25 23:03 ` [PATCH (v2) 10/11] " Simon Arlott 2015-11-25 23:03 ` Simon Arlott 2015-11-22 14:14 ` [PATCH 10/10] watchdog: bcm63xx_wdt: Use brcm,bcm6345-wdt device tree binding Simon Arlott 2015-11-22 14:14 ` Simon Arlott 2015-11-25 23:09 ` [PATCH (v2) 11/11] " Simon Arlott 2015-11-25 23:09 ` Simon Arlott 2015-11-22 22:12 ` [PATCH 1/4] clocksource: Add brcm,bcm6345-timer " Rob Herring 2015-11-23 15:33 ` Jonas Gorski 2015-11-23 18:55 ` [PATCH (v2) 1/10] " Simon Arlott 2015-11-23 18:55 ` Simon Arlott 2015-11-23 18:57 ` [PATCH (v2) 2/10] MIPS: bmips: Add bcm6345-l2-timer interrupt controller Simon Arlott 2015-11-23 18:57 ` Simon Arlott 2015-11-24 22:10 ` [PATCH (v3) " Simon Arlott 2015-11-24 22:10 ` Simon Arlott 2015-11-24 22:36 ` Florian Fainelli 2015-11-24 22:36 ` Florian Fainelli 2015-11-26 22:32 ` [PATCH (v4) 2/11] " Simon Arlott 2015-11-27 8:37 ` Thomas Gleixner 2015-11-27 8:37 ` Thomas Gleixner 2015-11-28 12:26 ` [PATCH (v5) 3/11] " Simon Arlott 2015-11-28 12:26 ` Simon Arlott 2015-12-01 0:22 ` Guenter Roeck 2015-12-01 0:22 ` Guenter Roeck 2016-05-09 12:01 ` Álvaro Fernández Rojas 2016-05-09 13:06 ` Guenter Roeck 2016-05-09 13:06 ` Guenter Roeck 2016-05-11 6:40 ` [PATCH 2/4] " Álvaro Fernández Rojas 2015-11-25 3:05 ` [PATCH (v2) 1/10] clocksource: Add brcm,bcm6345-timer device tree binding Rob Herring
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