2021-05-14 15:29:00

by Robin Gong

Subject: [PATCH v2] watchdog: imx2_wdt: avoid to ping before resume back

Since watchdog_ping_work is not freezable so that it maybe scheduled before
imx2_wdt_resume where watchdog clock enabled, hence, kernel will hang in
imx2_wdt_ping without clock, and then watchdog reset happen. Add clk_is_on
to prevent the above case by ignoring ping until watchdog driver resume
back indeed.

Signed-off-by: Robin Gong <[email protected]>
---
drivers/watchdog/imx2_wdt.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
index b84f80f..cc86018 100644
--- a/drivers/watchdog/imx2_wdt.c
+++ b/drivers/watchdog/imx2_wdt.c
@@ -65,6 +65,7 @@ struct imx2_wdt_device {
struct regmap *regmap;
struct watchdog_device wdog;
bool ext_reset;
+ bool clk_is_on;
};

static bool nowayout = WATCHDOG_NOWAYOUT;
@@ -160,6 +161,9 @@ static int imx2_wdt_ping(struct watchdog_device *wdog)
{
struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

+ if (!wdev->clk_is_on)
+ return 0;
+
regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ1);
regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ2);
return 0;
@@ -301,6 +305,8 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
if (ret)
return ret;

+ wdev->clk_is_on = true;
+
regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val);
wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;

@@ -361,6 +367,8 @@ static int __maybe_unused imx2_wdt_suspend(struct device *dev)

clk_disable_unprepare(wdev->clk);

+ wdev->clk_is_on = false;
+
return 0;
}

@@ -375,6 +383,8 @@ static int __maybe_unused imx2_wdt_resume(struct device *dev)
if (ret)
return ret;

+ wdev->clk_is_on = true;
+
if (watchdog_active(wdog) && !imx2_wdt_is_running(wdev)) {
/*
* If the watchdog is still active and resumes
--
2.7.4

2021-05-14 21:36:01

by Guenter Roeck

Subject: Re: [PATCH v2] watchdog: imx2_wdt: avoid to ping before resume back

On 5/14/21 10:21 AM, Robin Gong wrote:
> Since watchdog_ping_work is not freezable so that it maybe scheduled before
> imx2_wdt_resume where watchdog clock enabled, hence, kernel will hang in
> imx2_wdt_ping without clock, and then watchdog reset happen. Add clk_is_on
> to prevent the above case by ignoring ping until watchdog driver resume
> back indeed.
>
> Signed-off-by: Robin Gong <[email protected]>

Reviewed-by: Guenter Roeck <[email protected]>

> ---
> drivers/watchdog/imx2_wdt.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
> index b84f80f..cc86018 100644
> --- a/drivers/watchdog/imx2_wdt.c
> +++ b/drivers/watchdog/imx2_wdt.c
> @@ -65,6 +65,7 @@ struct imx2_wdt_device {
> struct regmap *regmap;
> struct watchdog_device wdog;
> bool ext_reset;
> + bool clk_is_on;
> };
>
> static bool nowayout = WATCHDOG_NOWAYOUT;
> @@ -160,6 +161,9 @@ static int imx2_wdt_ping(struct watchdog_device *wdog)
> {
> struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
>
> + if (!wdev->clk_is_on)
> + return 0;
> +
> regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ1);
> regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ2);
> return 0;
> @@ -301,6 +305,8 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
> if (ret)
> return ret;
>
> + wdev->clk_is_on = true;
> +
> regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val);
> wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
>
> @@ -361,6 +367,8 @@ static int __maybe_unused imx2_wdt_suspend(struct device *dev)
>
> clk_disable_unprepare(wdev->clk);
>
> + wdev->clk_is_on = false;
> +
> return 0;
> }
>
> @@ -375,6 +383,8 @@ static int __maybe_unused imx2_wdt_resume(struct device *dev)
> if (ret)
> return ret;
>
> + wdev->clk_is_on = true;
> +
> if (watchdog_active(wdog) && !imx2_wdt_is_running(wdev)) {
> /*
> * If the watchdog is still active and resumes
>