Re: [PATCH 4/10] watchdog: bcm63xx_wdt: Handle hardware interrupt and remove software timer

From	Jonas Gorski <jogo@openwrt.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 4/10] watchdog: bcm63xx_wdt: Handle hardware interrupt and remove software timer
Date	2015-11-25 21:20 +0100
Message-ID	<qyOHL-2Bf-3@gated-at.bofh.it> (permalink)
References	(3 earlier) <qxocG-2BX-5@gated-at.bofh.it> <qxsJj-5JA-1@gated-at.bofh.it> <qxDv3-4PJ-3@gated-at.bofh.it> <qxDv3-4PJ-1@gated-at.bofh.it> <qyqvM-3iT-29@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue, Nov 24, 2015 at 7:21 PM, Guenter Roeck <linux@roeck-us.net> wrote:
> On Sun, Nov 22, 2015 at 02:05:16PM +0000, Simon Arlott wrote:
>> There is a level triggered interrupt for the watchdog timer as part of
>> the bcm63xx_timer device. The interrupt occurs when the hardware watchdog
>> timer reaches 50% of the remaining time.
>>
>> It is not possible to mask the interrupt within the bcm63xx_timer device.
>> To get around this limitation, handle the interrupt by restarting the
>> watchdog with the current remaining time (which will be half the previous
>> timeout) so that the interrupt occurs again at 1/4th, 1/8th, etc. of the
>> original timeout value until the watchdog forces a reboot.
>>
>> The software timer was restarting the hardware watchdog with a 85 second
>> timeout until the software timer expired, and then causing a panic()
>> about 42.5 seconds later when the hardware interrupt occurred. The
>> hardware watchdog would not reboot until a further 42.5 seconds had
>> passed.
>>
>> Remove the software timer and rely on the hardware timer directly,
>> reducing the maximum timeout from 256 seconds to 85 seconds
>> (2^32 / WDT_HZ).
>>
>
> Florian,
>
> can you have a look into this patch and confirm that there is no better
> way to clear the interrupt status ?

While the watchdog interrupt can't be masked, it should be able to be
cleared by writing 1 to the appropriate bit in the timer block's
interrupt status register. At least the broadcom sources do so.


Jonas
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Thread

[PATCH 1/4] clocksource: Add brcm,bcm6345-timer device tree binding Simon Arlott <simon@fire.lp0.eu> - 2015-11-21 20:10 +0100
  [PATCH 2/4] MIPS: bmips: Add bcm6345-l2-timer interrupt controller Simon Arlott <simon@fire.lp0.eu> - 2015-11-21 20:10 +0100
  [PATCH 4/4] MIPS: bmips: Convert bcm63xx_wdt to use WATCHDOG_CORE Simon Arlott <simon@fire.lp0.eu> - 2015-11-21 20:10 +0100
    Re: [PATCH 4/4] MIPS: bmips: Convert bcm63xx_wdt to use WATCHDOG_CORE Guenter Roeck <linux@roeck-us.net> - 2015-11-21 22:40 +0100
      Re: [PATCH 4/4] MIPS: bmips: Convert bcm63xx_wdt to use WATCHDOG_CORE Simon Arlott <simon@fire.lp0.eu> - 2015-11-21 22:50 +0100
        Re: [PATCH 4/4] MIPS: bmips: Convert bcm63xx_wdt to use WATCHDOG_CORE Guenter Roeck <linux@roeck-us.net> - 2015-11-22 03:40 +0100
          [PATCH 6/10] watchdog: bcm63xx_wdt: Obtain watchdog clock HZ from  "periph" clk Simon Arlott <simon@fire.lp0.eu> - 2015-11-22 15:10 +0100
            Re: [PATCH 6/10] watchdog: bcm63xx_wdt: Obtain watchdog clock HZ from  "periph" clk Jonas Gorski <jogo@openwrt.org> - 2015-11-23 16:10 +0100
              Re: [PATCH 6/10] watchdog: bcm63xx_wdt: Obtain watchdog clock HZ  from "periph" clk Florian Fainelli <f.fainelli@gmail.com> - 2015-11-23 19:30 +0100
                Re: [PATCH 6/10] watchdog: bcm63xx_wdt: Obtain watchdog clock HZ from  "periph" clk Simon Arlott <simon@fire.lp0.eu> - 2015-11-23 20:10 +0100
            [PATCH (v2) 6/10] watchdog: bcm63xx_wdt: Obtain watchdog clock HZ  from "periph" clk "Simon Arlott" <simon@fire.lp0.eu> - 2015-11-24 23:20 +0100
              Re: [PATCH (v2) 6/10] watchdog: bcm63xx_wdt: Obtain watchdog clock  HZ from "periph" clk Florian Fainelli <f.fainelli@gmail.com> - 2015-11-24 23:50 +0100
                [PATCH (v3) 6/11] watchdog: bcm63xx_wdt: Obtain watchdog clock HZ  from "periph" clk Simon Arlott <simon@fire.lp0.eu> - 2015-11-25 23:50 +0100
          [PATCH 7/10] watchdog: bcm63xx_wdt: Add get_timeleft function Simon Arlott <simon@fire.lp0.eu> - 2015-11-22 15:10 +0100
            [PATCH (v2) 7/10] watchdog: bcm63xx_wdt: Add get_timeleft function "Simon Arlott" <simon@fire.lp0.eu> - 2015-11-24 23:20 +0100
              Re: [PATCH (v2) 7/10] watchdog: bcm63xx_wdt: Add get_timeleft function Florian Fainelli <f.fainelli@gmail.com> - 2015-11-24 23:50 +0100
              Re: [PATCH (v2) 7/10] watchdog: bcm63xx_wdt: Add get_timeleft  function Guenter Roeck <linux@roeck-us.net> - 2015-11-25 04:00 +0100
                Re: [PATCH (v2) 7/10] watchdog: bcm63xx_wdt: Add get_timeleft  function Simon Arlott <simon@fire.lp0.eu> - 2015-11-25 09:20 +0100
                [PATCH (v4) 7/11] watchdog: bcm63xx_wdt: Add get_timeleft function Simon Arlott <simon@fire.lp0.eu> - 2015-11-26 00:00 +0100
                [PATCH (v4) 8/11] watchdog: bcm63xx_wdt: Warn if the watchdog is  currently running Simon Arlott <simon@fire.lp0.eu> - 2015-11-26 00:00 +0100
                [PATCH (v3) 7/11] watchdog: bcm63xx_wdt: Add get_timeleft function Simon Arlott <simon@fire.lp0.eu> - 2015-11-26 00:00 +0100
          Re: [PATCH 4/10] (Was: [PATCH 4/4]) MIPS: bmips: Convert bcm63xx_wdt  to use WATCHDOG_CORE Simon Arlott <simon@fire.lp0.eu> - 2015-11-22 15:10 +0100
            [PATCH 5/10] watchdog: bcm63xx_wdt: Use WATCHDOG_CORE Simon Arlott <simon@fire.lp0.eu> - 2015-11-22 15:10 +0100
              Re: [PATCH 5/10] watchdog: bcm63xx_wdt: Use WATCHDOG_CORE Guenter Roeck <linux@roeck-us.net> - 2015-11-25 03:50 +0100
                Re: [PATCH 5/10] watchdog: bcm63xx_wdt: Use WATCHDOG_CORE "Simon Arlott" <simon@fire.lp0.eu> - 2015-11-25 14:10 +0100
                Re: [PATCH 5/10] watchdog: bcm63xx_wdt: Use WATCHDOG_CORE Guenter Roeck <linux@roeck-us.net> - 2015-11-25 15:20 +0100
                Re: [PATCH 5/10] watchdog: bcm63xx_wdt: Use WATCHDOG_CORE Simon Arlott <simon@fire.lp0.eu> - 2015-11-25 20:50 +0100
                [PATCH (v3) 5/11] watchdog: bcm63xx_wdt: Use WATCHDOG_CORE Simon Arlott <simon@fire.lp0.eu> - 2015-11-25 23:50 +0100
            [PATCH 4/10] watchdog: bcm63xx_wdt: Handle hardware interrupt and  remove software timer Simon Arlott <simon@fire.lp0.eu> - 2015-11-22 15:10 +0100
              Re: [PATCH 4/10] watchdog: bcm63xx_wdt: Handle hardware interrupt  and remove software timer Guenter Roeck <linux@roeck-us.net> - 2015-11-24 19:30 +0100
                Re: [PATCH 4/10] watchdog: bcm63xx_wdt: Handle hardware interrupt and  remove software timer Jonas Gorski <jogo@openwrt.org> - 2015-11-25 21:20 +0100
                Re: [PATCH 4/10] watchdog: bcm63xx_wdt: Handle hardware interrupt and  remove software timer Simon Arlott <simon@fire.lp0.eu> - 2015-11-25 21:30 +0100
              [PATCH (v2) 4/10] watchdog: bcm63xx_wdt: Handle hardware interrupt  and remove software timer Simon Arlott <simon@fire.lp0.eu> - 2015-11-25 23:40 +0100
            [PATCH 8/10] watchdog: bcm63xx_wdt: Remove dependency on mach-bcm63xx  functions/defines Simon Arlott <simon@fire.lp0.eu> - 2015-11-22 15:20 +0100
            [PATCH 10/10] watchdog: bcm63xx_wdt: Use brcm,bcm6345-wdt device tree  binding Simon Arlott <simon@fire.lp0.eu> - 2015-11-22 15:20 +0100
              [PATCH (v2) 11/11] watchdog: bcm63xx_wdt: Use brcm,bcm6345-wdt device  tree binding Simon Arlott <simon@fire.lp0.eu> - 2015-11-26 00:20 +0100
            [PATCH 9/10] watchdog: bcm63xx_wdt: Use bcm63xx_timer interrupt  directly Simon Arlott <simon@fire.lp0.eu> - 2015-11-22 15:20 +0100
              [PATCH (v2) 10/11] watchdog: bcm63xx_wdt: Use bcm63xx_timer interrupt  directly Simon Arlott <simon@fire.lp0.eu> - 2015-11-26 00:10 +0100
  [PATCH 3/4] watchdog: Add brcm,bcm6345-wdt device tree binding Simon Arlott <simon@fire.lp0.eu> - 2015-11-21 20:10 +0100
    Re: [PATCH 3/4] watchdog: Add brcm,bcm6345-wdt device tree binding Rob Herring <robh@kernel.org> - 2015-11-22 23:20 +0100
  Re: [PATCH 1/4] clocksource: Add brcm,bcm6345-timer device tree  binding Rob Herring <robh@kernel.org> - 2015-11-22 23:20 +0100
  Re: [PATCH 1/4] clocksource: Add brcm,bcm6345-timer device tree binding Jonas Gorski <jogo@openwrt.org> - 2015-11-23 16:40 +0100
    [PATCH (v2) 2/10] MIPS: bmips: Add bcm6345-l2-timer interrupt  controller Simon Arlott <simon@fire.lp0.eu> - 2015-11-23 20:00 +0100
      [PATCH (v3) 2/10] MIPS: bmips: Add bcm6345-l2-timer interrupt  controller "Simon Arlott" <simon@fire.lp0.eu> - 2015-11-24 23:20 +0100
        Re: [PATCH (v3) 2/10] MIPS: bmips: Add bcm6345-l2-timer interrupt  controller Florian Fainelli <f.fainelli@gmail.com> - 2015-11-24 23:40 +0100
          [PATCH (v4) 2/11] MIPS: bmips: Add bcm6345-l2-timer interrupt  controller Simon Arlott <simon@fire.lp0.eu> - 2015-11-26 23:40 +0100
            Re: [PATCH (v4) 2/11] MIPS: bmips: Add bcm6345-l2-timer interrupt  controller Thomas Gleixner <tglx@linutronix.de> - 2015-11-27 09:40 +0100
              [PATCH (v5) 3/11] MIPS: bmips: Add bcm6345-l2-timer interrupt  controller Simon Arlott <simon@fire.lp0.eu> - 2015-11-28 13:30 +0100
    [PATCH (v2) 1/10] clocksource: Add brcm,bcm6345-timer device tree  binding Simon Arlott <simon@fire.lp0.eu> - 2015-11-23 20:00 +0100
      Re: [PATCH (v2) 1/10] clocksource: Add brcm,bcm6345-timer device  tree binding Rob Herring <robh@kernel.org> - 2015-11-25 04:10 +0100

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