Messages in this thread | | | Subject | Re: [PATCH v2 2/3] watchdog: sama5d4: Fix setting timeout when watchdog is disabled | From | Guenter Roeck <> | Date | Sun, 19 Feb 2017 08:57:35 -0800 |
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On 02/17/2017 07:16 AM, Alexandre Belloni wrote: > On 17/02/2017 at 06:40:33 -0800, Guenter Roeck wrote: >> On 02/16/2017 11:30 AM, Alexandre Belloni wrote: >>> The datasheet states: "When setting the WDDIS bit, and while it is set, the >>> fields WDV and WDD must not be modified." >>> >>> Ensure WDDIS is not set when changing the timeout and set it afterwards if >>> the watchdog was disabled. >>> >>> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com> >>> --- >>> Changes in v2: >>> - new patch >>> drivers/watchdog/sama5d4_wdt.c | 9 ++++++++- >>> 1 file changed, 8 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c >>> index 2c6f5a70ae67..2a60251806d2 100644 >>> --- a/drivers/watchdog/sama5d4_wdt.c >>> +++ b/drivers/watchdog/sama5d4_wdt.c >>> @@ -90,11 +90,18 @@ static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd, >>> u32 reg; >>> >>> reg = wdt_read(wdt, AT91_WDT_MR); >>> + >>> + if (reg & AT91_WDT_WDDIS) >>> + wdt_write(wdt, AT91_WDT_MR, reg & ~AT91_WDT_WDDIS); >>> + >>> reg &= ~AT91_WDT_WDV; >>> reg &= ~AT91_WDT_WDD; >>> reg |= AT91_WDT_SET_WDV(value); >>> reg |= AT91_WDT_SET_WDD(value); >>> - wdt_write(wdt, AT91_WDT_MR, reg); >>> + wdt_write(wdt, AT91_WDT_MR, reg & ~AT91_WDT_WDDIS); >>> + >>> + if (reg & AT91_WDT_WDDIS) >>> + wdt_write(wdt, AT91_WDT_MR, reg); >>> >> That means if the watchdog is running, the timeout would not be updated. >> It should be updated no matter if it is running or not. >> > > No, it is enabling the watchdog, then changing WDV and WDD and finally > disabling the watchdog if necessary. So, WDV and WDD are always changed. > You are correct. Sorry for the noise.
Seems odd that the watchdog must be _running_ to change the timeout. Usually, if there is a restriction, it is the opposite. I hope this doesn't cause race conditions, where the watchdog fires immediately after being enabled due to a low timeout.
Guenter
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