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

From Simon Arlott <simon@fire.lp0.eu>
Newsgroups linux.kernel
Subject Re: [PATCH 4/10] watchdog: bcm63xx_wdt: Handle hardware interrupt and remove software timer
Date 2015-11-25 21:30 +0100
Message-ID <qyORt-2F7-35@gated-at.bofh.it> (permalink)
References (4 earlier) <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> <qyOHL-2Bf-3@gated-at.bofh.it>
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On 25/11/15 20:14, Jonas Gorski wrote:
> 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.

Not according to the hardware itself:
[    6.674626] watchdog watchdog0: warning timer fired, reboot in 7499ms
[    6.681212] irq_bcm6345_l2_timer: bcm6345_timer_write_int_status: b0000083=08
[    6.688583] watchdog watchdog0: warning timer fired, reboot in 7486ms
[    6.695181] irq_bcm6345_l2_timer: bcm6345_timer_write_int_status: b0000083=08
[    6.702554] watchdog watchdog0: warning timer fired, reboot in 7472ms
[    6.709158] irq_bcm6345_l2_timer: bcm6345_timer_write_int_status: b0000083=08
[    6.716529] watchdog watchdog0: warning timer fired, reboot in 7458ms
[    6.723135] irq_bcm6345_l2_timer: bcm6345_timer_write_int_status: b0000083=08
[    6.730538] watchdog watchdog0: warning timer fired, reboot in 7444ms
[    6.737121] irq_bcm6345_l2_timer: bcm6345_timer_write_int_status: b0000083=08
[    6.744482] watchdog watchdog0: warning timer fired, reboot in 7430ms
[    6.751090] irq_bcm6345_l2_timer: bcm6345_timer_write_int_status: b0000083=08


typedef struct Timer {
    uint16        unused0;
    byte          TimerMask;
#define TIMER0EN        0x01
#define TIMER1EN        0x02
#define TIMER2EN        0x04
    byte          TimerInts;
#define TIMER0          0x01
#define TIMER1          0x02
#define TIMER2          0x04
#define WATCHDOG        0x08
...

-- 
Simon Arlott
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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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