| Message ID | 20241203095744.3001795-1-mac@mcrowe.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] watchdog: sp805: Report correct timeleft at maximum | expand |
On 12/3/24 01:57, Mike Crowe wrote: > sp805_wdt::load_val is of type unsigned int. When the interrupt is > inactive wdt_timeleft adds one to the value, and then adds that to the > value used to calculate the time remaining. Unfortunately it's not > unlikely that load_val contains LOAD_MAX, which is 0xFFFFFFFF and wraps > to zero when one is added to it, resulting in the time left being > understated by about 21.7s. Fix this by ensuring the addition happens as > 64-bit. > > Signed-off-by: Mike Crowe <mac@mcrowe.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Please provide change logs in future patches. Guenter > --- > drivers/watchdog/sp805_wdt.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c > index 109e2e37e8f0..4400c439c718 100644 > --- a/drivers/watchdog/sp805_wdt.c > +++ b/drivers/watchdog/sp805_wdt.c > @@ -128,7 +128,7 @@ static unsigned int wdt_timeleft(struct watchdog_device *wdd) > > /*If the interrupt is inactive then time left is WDTValue + WDTLoad. */ > if (!(readl_relaxed(wdt->base + WDTRIS) & INT_MASK)) > - load += wdt->load_val + 1; > + load += (u64)wdt->load_val + 1; > spin_unlock(&wdt->lock); > > return div_u64(load, wdt->rate);
diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c index 109e2e37e8f0..4400c439c718 100644 --- a/drivers/watchdog/sp805_wdt.c +++ b/drivers/watchdog/sp805_wdt.c @@ -128,7 +128,7 @@ static unsigned int wdt_timeleft(struct watchdog_device *wdd) /*If the interrupt is inactive then time left is WDTValue + WDTLoad. */ if (!(readl_relaxed(wdt->base + WDTRIS) & INT_MASK)) - load += wdt->load_val + 1; + load += (u64)wdt->load_val + 1; spin_unlock(&wdt->lock); return div_u64(load, wdt->rate);
sp805_wdt::load_val is of type unsigned int. When the interrupt is inactive wdt_timeleft adds one to the value, and then adds that to the value used to calculate the time remaining. Unfortunately it's not unlikely that load_val contains LOAD_MAX, which is 0xFFFFFFFF and wraps to zero when one is added to it, resulting in the time left being understated by about 21.7s. Fix this by ensuring the addition happens as 64-bit. Signed-off-by: Mike Crowe <mac@mcrowe.com> --- drivers/watchdog/sp805_wdt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)