On 4/21/21 8:46 PM, 王擎 wrote:

quoted

On 4/21/21 7:45 PM, Wang Qing wrote:

quoted

Use the bark interrupt as the pretimeout notifier if available.

When the watchdog timer expires in dual mode, an interrupt will be
triggered first, then the timing restarts. The reset signal will be
initiated when the timer expires again.

The pretimeout notification shall occur at timeout-sec/2.

V2:
- panic() by default if WATCHDOG_PRETIMEOUT_GOV is not enabled.

V3:
- Modify the pretimeout behavior, manually reset after the pretimeout
- is processed and wait until timeout.

V4:
- Remove pretimeout related processing. 
- Add dual mode control separately.

V5:
- Fix some formatting and printing problems.

V6:
- Realize pretimeout processing through dualmode.

Signed-off-by: Wang Qing <redacted>
---
 drivers/watchdog/mtk_wdt.c | 53 +++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 48 insertions(+), 5 deletions(-)

diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
index 97ca993..ebc648b
--- a/drivers/watchdog/mtk_wdt.c
+++ b/drivers/watchdog/mtk_wdt.c

@@ -25,6 +25,7 @@
 #include <linux/reset-controller.h>
 #include <linux/types.h>
 #include <linux/watchdog.h>
+#include <linux/interrupt.h>
 
 #define WDT_MAX_TIMEOUT		31
 #define WDT_MIN_TIMEOUT		1

@@ -184,15 +185,22 @@ static int mtk_wdt_set_timeout(struct watchdog_device *wdt_dev,
 {
 	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
 	void __iomem *wdt_base = mtk_wdt->wdt_base;
+	unsigned int timeout_interval;
 	u32 reg;
 
-	wdt_dev->timeout = timeout;
+	timeout_interval = wdt_dev->timeout = timeout;
+	/*
+	 * In dual mode, irq will be triggered at timeout/2
+	 * the real timeout occurs at timeout
+	 */
+	if (wdt_dev->pretimeout)
+		timeout_interval = wdt_dev->pretimeout = timeout/2;

Please run checkpatch --strict and fix what it reports.
Also, there should be a set_pretimeout function to set the
pretimeout. It is ok to update it here, but it should be set
in its own function to make sure that the actual value
is reported back to userspace.

Thanks,
Guenter

The reason why the set_pretimeout interface is not provided is 
because the pretimeout is fixed after the timeout is set,  we need
to modify timeout after setting pretimeout, which is puzzling.

What you need to do is to set pretimeout = timeout / 2 if a pretimeout
is set to a value != 0. Just like we adjust timeout to valid values
when set, we adjust pretimeout as well. I don't see a problem with that.

Guenter