Re: [Linaro-acpi] [PATCH v8 5/5] Watchdog: introduce ARM SBSA watchdog driver

From: Guenter Roeck
Date: Thu Nov 05 2015 - 00:13:56 EST

On 11/04/2015 05:59 PM, Timur Tabi wrote:
On Tue, Oct 27, 2015 at 11:06 AM, <fu.wei@xxxxxxxxxx> wrote:
+static irqreturn_t sbsa_gwdt_interrupt(int irq, void *dev_id)
+ struct sbsa_gwdt *gwdt = (struct sbsa_gwdt *)dev_id;
+ struct watchdog_device *wdd = &gwdt->wdd;
+ /* We don't use pretimeout, trigger WS1 now */
+ if (!wdd->pretimeout)
+ sbsa_gwdt_set_wcv(wdd, 0);

So I'm still concerned about the fact this driver depends on an
interrupt handler in order to properly program the hardware. Unlike
some other devices, the SBSA watchdog does not need assistance to
reset on a timeout -- it is a "fire and forget" device. What happens
if there is a hard lockup, and interrupts no longer work?

Keep in mind that 99% of watchdog daemons will not enable the
pre-timeout feature because it's new.

Same here, really.

I would feel much more comfortable if the driver would just use the standard
watchdog timeout and live with (worst case) 20 seconds timeout for now.
This limitation will be gone once the infrastructure is in place to handle
such short timeouts in the watchdog core. Until then, I would argue that the
system designers asked for it if they really select the highest possible
clock rate.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at