On 12/11/2014 09:20, Timo Kokkonen :
> Hi,
>
> On 10/23/14 13:40, Timo Kokkonen wrote:
>> By default the driver will start a kernel timer which keeps on kicking
>> the watchdog HW until user space has opened the watchdog
>> device. Usually this is desirable as the watchdog HW is running by
>> default and the user space may not have any watchdog daemon running at
>> all.
>>
>> However, on production systems it may be mandatory that also early
>> crashes and lockups will lead to a watchdog reset, even if they happen
>> before the user space has opened the watchdog device.
>>
>> To resolve the issue, add a new device tree property
>> "atmel,no-early-timer" which will prevent the kernel timer from
>> pinging the watchdog HW on behalf of user space. The default is still
>> to use kernel timer, but more strict behavior can be enabled via the
>> device tree property.
>>
>
> Any thoughts on this one? Should I resend this with some more people or
> lists to get someone to comment or review this patch?
I would like to know if this property added to the device-tree is
already defined by another watchdog timer.
Indeed, it seems a pretty generic behavior and I am surprised it doesn't
have an already existing implementation.
...
>> Signed-off-by: Timo Kokkonen <timo.kokkonen@xxxxxxxxxx>
>> ---
>> Documentation/devicetree/bindings/watchdog/atmel-wdt.txt | 4 ++++
>> drivers/watchdog/at91sam9_wdt.c | 6 +++++-
>> 2 files changed, 9 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt b/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt
>> index f90e294..1b9289e 100644
>> --- a/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt
>> +++ b/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt
>> @@ -28,6 +28,10 @@ Optional properties:
>> entering idle state.
>> - atmel,dbg-halt : Should be present if you want to stop the watchdog when
>> entering debug state.
>> +- atmel,no-early-timer : Should be present if you want to let the
>> + watchdog timer to expire even before user space has opened the
>> + device. If not set, a kernel timer will keep on pinging the
>> + watchdog until it is opened.
>>
>> Example:
>> watchdog@fffffd40 {
>> diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c
>> index 489729b..8cac712 100644
>> --- a/drivers/watchdog/at91sam9_wdt.c
>> +++ b/drivers/watchdog/at91sam9_wdt.c
>> @@ -89,6 +89,7 @@ struct at91wdt {
>> u32 mr_mask;
>> unsigned long heartbeat; /* WDT heartbeat in jiffies */
>> bool nowayout;
>> + bool no_early_timer;
>> unsigned int irq;
>> };
>>
>> @@ -122,7 +123,7 @@ static void at91_ping(unsigned long data)
>> {
>> struct at91wdt *wdt = (struct at91wdt *)data;
>> if (time_before(jiffies, wdt->next_heartbeat) ||
>> - !watchdog_active(&wdt->wdd)) {
>> + (!watchdog_active(&wdt->wdd) && !wdt->no_early_timer)) {
... Nitpicking: there seems to be a indentation mismatch here: use tab +
spaces to align to previous line...
>> at91_wdt_reset(wdt);
>> mod_timer(&wdt->timer, jiffies + wdt->heartbeat);
>> } else {
>> @@ -316,6 +317,9 @@ static int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt)
>>
>> wdt->mr |= max | ((max - min) << 16);
>>
>> + if (of_property_read_bool(np, "atmel,no-early-timer"))
>> + wdt->no_early_timer = 1;
>> +
>> return 0;
>> }
>> #else
Otherwise, it seems clean. Can you please re-send a version with the
Device tree maintainer in CC?
Best regards,
--
Nicolas Ferre
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