Hi Mark,

On Wed, 4 Mar 2015 18:38:09 +0000
Mark Rutland [off-list ref] wrote:

Hi Boris,

On Mon, Mar 02, 2015 at 09:18:17AM +0000, Boris Brezillon wrote:

quoted

The watchdog interrupt (only used when activating software watchdog)
shouldn't be suspended when entering suspend mode, because it is shared
with a timer device (which request the line with IRQF_NO_SUSPEND) and once
the watchdog "Mode Register" has been written, it cannot be changed (which
means we cannot disable the watchdog interrupt when entering suspend).

Signed-off-by: Boris Brezillon <redacted>
---
 drivers/watchdog/at91sam9_wdt.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c
index 6df9405..1443b3c 100644
--- a/drivers/watchdog/at91sam9_wdt.c
+++ b/drivers/watchdog/at91sam9_wdt.c

@@ -208,7 +208,8 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
 
 	if ((tmp & AT91_WDT_WDFIEN) && wdt->irq) {
 		err = request_irq(wdt->irq, wdt_interrupt,
-				  IRQF_SHARED | IRQF_IRQPOLL,
+				  IRQF_SHARED | IRQF_IRQPOLL |
+				  IRQF_NO_SUSPEND,

I'm a little confused by this. What happens if the watchdog fires when
we're actually in the suspended state (when IRQF_NO_SUSPEND interrupts
aren't guaranteed to be delivered).

It reboot the system.

Does this rely on the watchdog IRQ being taken while in the actual
suspended state (but not waking up the system while handling it)?

Actually this interrupt handler is just here to reboot the system if the
user didn't refresh the watchdog.
Do we really have to wake up the system to then call emergency_restart ?


-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com