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| author | Boris BREZILLON <b.brezillon@overkiz.com> | 2013-11-03 18:52:44 +0100 |
|---|---|---|
| committer | Wim Van Sebroeck <wim@iguana.be> | 2014-01-28 21:34:55 +0100 |
| commit | f72fa00f8ab216ee484d61de17ddc84712456c3a (patch) | |
| tree | ca9aff9149e04e11f9669c8e3af8c7516e39fc7d /drivers/watchdog | |
| parent | a04c3f01d33f4661424deeff67913699a0910c53 (diff) | |
| download | lwn-f72fa00f8ab216ee484d61de17ddc84712456c3a.tar.gz lwn-f72fa00f8ab216ee484d61de17ddc84712456c3a.zip | |
watchdog: at91sam9_wdt: increase security margin on watchdog counter reset
Try to reset the watchdog counter 4 or 2 times more often than actually
requested, to avoid spurious watchdog reset.
If this is not possible because of the min_heartbeat value, reset it at
the min_heartbeat period.
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Diffstat (limited to 'drivers/watchdog')
| -rw-r--r-- | drivers/watchdog/at91sam9_wdt.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c index ab0c4e0165d1..489729b26298 100644 --- a/drivers/watchdog/at91sam9_wdt.c +++ b/drivers/watchdog/at91sam9_wdt.c @@ -158,6 +158,7 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt) int err; u32 mask = wdt->mr_mask; unsigned long min_heartbeat = 1; + unsigned long max_heartbeat; struct device *dev = &pdev->dev; tmp = wdt_read(wdt, AT91_WDT_MR); @@ -181,23 +182,29 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt) if (delta < value) min_heartbeat = ticks_to_hz_roundup(value - delta); - wdt->heartbeat = ticks_to_hz_rounddown(value); - if (!wdt->heartbeat) { + max_heartbeat = ticks_to_hz_rounddown(value); + if (!max_heartbeat) { dev_err(dev, "heartbeat is too small for the system to handle it correctly\n"); return -EINVAL; } - if (wdt->heartbeat < min_heartbeat + 4) { + /* + * Try to reset the watchdog counter 4 or 2 times more often than + * actually requested, to avoid spurious watchdog reset. + * If this is not possible because of the min_heartbeat value, reset + * it at the min_heartbeat period. + */ + if ((max_heartbeat / 4) >= min_heartbeat) + wdt->heartbeat = max_heartbeat / 4; + else if ((max_heartbeat / 2) >= min_heartbeat) + wdt->heartbeat = max_heartbeat / 2; + else wdt->heartbeat = min_heartbeat; + + if (max_heartbeat < min_heartbeat + 4) dev_warn(dev, "min heartbeat and max heartbeat might be too close for the system to handle it correctly\n"); - if (wdt->heartbeat < 4) - dev_warn(dev, - "heartbeat might be too small for the system to handle it correctly\n"); - } else { - wdt->heartbeat -= 4; - } if ((tmp & AT91_WDT_WDFIEN) && wdt->irq) { err = request_irq(wdt->irq, wdt_interrupt, |