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SubjectRe: [PATCH 2/3] watchdog: da9063: Use pre configured timeout when watchdog is running
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On 3/30/20 9:38 AM, Adam Thomson wrote:
> On 26 March 2020 15:02, Stefan Riedmueller wrote:
>
>> If the watchdog is already running during probe use its pre-configured
>> timeout instead of a default timeout to make sure the watchdog is pinged
>> in time until userspace takes over.
>
> At least for this driver I don't think there's an issue here with regards to
> not pinging in time. Calling 'da9063_wdt_update_timeout()', as it currently
> does in the probe() when the watchdog is already active, actually disables the
> watchdog before then setting a new timeout value, so by that method we're
> avoiding a timeout and starting a new timer period.
>
> To my mind the timeout value should come from DT if possible, which I would
> assume for the most part would match whatever is defined in the bootloader as
> well, unless I'm mistaken. If that's not available though then I would maybe
> agree on falling back to a value that was already programmed in the bootloader
> rather than the driver default which should be the last resort.
>
Agreed.

Guenter

>>
>> Signed-off-by: Stefan Riedmueller <s.riedmueller@phytec.de>
>> ---
>> drivers/watchdog/da9063_wdt.c | 29 ++++++++++++++++++-----------
>> 1 file changed, 18 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/watchdog/da9063_wdt.c b/drivers/watchdog/da9063_wdt.c
>> index 3d65e92a4e3f..34d0c4f03814 100644
>> --- a/drivers/watchdog/da9063_wdt.c
>> +++ b/drivers/watchdog/da9063_wdt.c
>> @@ -46,15 +46,16 @@ static unsigned int da9063_wdt_timeout_to_sel(unsigned
>> int secs)
>> }
>>
>> /*
>> - * Return 0 if watchdog is disabled, else non zero.
>> + * Read the currently active timeout.
>> + * Zero means the watchdog is disabled.
>> */
>> -static unsigned int da9063_wdt_is_running(struct da9063 *da9063)
>> +static unsigned int da9063_wdt_read_timeout(struct da9063 *da9063)
>> {
>> unsigned int val;
>>
>> regmap_read(da9063->regmap, DA9063_REG_CONTROL_D, &val);
>>
>> - return val & DA9063_TWDSCALE_MASK;
>> + return wdt_timeout[val & DA9063_TWDSCALE_MASK];
>> }
>>
>> static int da9063_wdt_disable_timer(struct da9063 *da9063)
>> @@ -191,6 +192,7 @@ static int da9063_wdt_probe(struct platform_device
>> *pdev)
>> struct device *dev = &pdev->dev;
>> struct da9063 *da9063;
>> struct watchdog_device *wdd;
>> + int timeout;
>>
>> if (!dev->parent)
>> return -EINVAL;
>> @@ -214,15 +216,20 @@ static int da9063_wdt_probe(struct platform_device
>> *pdev)
>> watchdog_set_restart_priority(wdd, 128);
>> watchdog_set_drvdata(wdd, da9063);
>>
>> - /* Set default timeout, maybe override it with DT value, scale it */
>> - wdd->timeout = DA9063_WDG_TIMEOUT;
>> - watchdog_init_timeout(wdd, 0, dev);
>> - da9063_wdt_set_timeout(wdd, wdd->timeout);
>> -
>> - /* Change the timeout to the default value if the watchdog is running */
>> - if (da9063_wdt_is_running(da9063)) {
>> - da9063_wdt_update_timeout(da9063, wdd->timeout);
>> + /*
>> + * Use pre-configured timeout if watchdog is already running.
>> + * Otherwise set default timeout, maybe override it with DT value,
>> + * scale it
>> + */
>> + timeout = da9063_wdt_read_timeout(da9063);
>> + if (timeout) {
>> + wdd->timeout = timeout;
>> set_bit(WDOG_HW_RUNNING, &wdd->status);
>> + dev_info(da9063->dev, "watchdog is running (%u s)", timeout);
>> + } else {
>> + wdd->timeout = DA9063_WDG_TIMEOUT;
>> + watchdog_init_timeout(wdd, 0, dev);
>> + da9063_wdt_set_timeout(wdd, wdd->timeout);
>> }
>>
>> return devm_watchdog_register_device(dev, wdd);
>> --
>> 2.23.0
>

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