Re: [PATCH v2] watchdog: omap_wdt: Add 'early_disable' module parameter

From: Guenter Roeck
Date: Tue Sep 16 2014 - 11:49:31 EST


On Tue, Sep 16, 2014 at 04:20:28PM +0200, Rostislav Lisovy wrote:
> This parameter makes it possible to control if the watchdog
> is being disabled during initialization or will stay enabled
> in case it was previously initialized in the bootloader.
>
> To maintain the existing behavior, the default value is 'true',
> thus the watchdog is disabled during initialization.
>
> This new feature is highly inspired by the w83627hf_wdt.c
>
> Signed-off-by: Rostislav Lisovy <lisovy@xxxxxxxxx>
> ---
> Changes since v1:
> * Fix Runtime PM device usage counter leaking (Guenter Roeck)
> * Remove the unnecessary message informing about "stopping the watchdog"
> (Guenter Roeck)
> * Fix proper setting of "omap_wdt_users"
>
> drivers/watchdog/omap_wdt.c | 26 ++++++++++++++++++++------
> 1 file changed, 20 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/watchdog/omap_wdt.c b/drivers/watchdog/omap_wdt.c
> index 3691b15..abf3b62 100644
> --- a/drivers/watchdog/omap_wdt.c
> +++ b/drivers/watchdog/omap_wdt.c
> @@ -53,6 +53,10 @@ static unsigned timer_margin;
> module_param(timer_margin, uint, 0);
> MODULE_PARM_DESC(timer_margin, "initial watchdog timeout (in seconds)");
>
> +static bool early_disable = true;
> +module_param(early_disable, bool, 0);
> +MODULE_PARM_DESC(early_disable, "Disable watchdog at boot time (default=1)");
> +
> struct omap_wdt_dev {
> void __iomem *base; /* physical */
> struct device *dev;
> @@ -128,9 +132,11 @@ static int omap_wdt_start(struct watchdog_device *wdog)
>
> mutex_lock(&wdev->lock);
>
> - wdev->omap_wdt_users = true;
> -
> - pm_runtime_get_sync(wdev->dev);
> + /* The watchdog was disabled in probe function */
> + if (early_disable) {

I think this should be
if (!wdev->omap_wdt_users) {

> + wdev->omap_wdt_users = true;
> + pm_runtime_get_sync(wdev->dev);
> + }
>
> /* initialize prescaler */
> while (readl_relaxed(base + OMAP_WATCHDOG_WPS) & 0x01)
> @@ -218,7 +224,7 @@ static int omap_wdt_probe(struct platform_device *pdev)
> if (!wdev)
> return -ENOMEM;
>
> - wdev->omap_wdt_users = false;
> + wdev->omap_wdt_users = (early_disable) ? false : true;

I don't immediately see what early_disable (a boot flag) has to do with
omap_wdt_users which is supposed to show if the watchdog is running or not.
Also see below.

> wdev->dev = &pdev->dev;
> wdev->wdt_trgr_pattern = 0x1234;
> mutex_init(&wdev->lock);
> @@ -255,7 +261,14 @@ static int omap_wdt_probe(struct platform_device *pdev)
> omap_wdt->bootstatus = (rs & (1 << OMAP_MPU_WD_RST_SRC_ID_SHIFT)) ?
> WDIOF_CARDRESET : 0;
>
> - omap_wdt_disable(wdev);
> + if (early_disable) {
> + omap_wdt_disable(wdev);
> + } else {
> + pr_info("Watchdog already running. Resetting timeout to %d sec\n",
> + omap_wdt->timeout);

How do you know that the watchdog was already running ?
Seems to me you are just making an assumption that it is running
without really knowing for sure.

> + omap_wdt_set_timeout(omap_wdt, omap_wdt->timeout);
> + omap_wdt_ping(omap_wdt);
> + }
>
> ret = watchdog_register_device(omap_wdt);
> if (ret) {
> @@ -267,7 +280,8 @@ static int omap_wdt_probe(struct platform_device *pdev)
> readl_relaxed(wdev->base + OMAP_WATCHDOG_REV) & 0xFF,
> omap_wdt->timeout);
>
> - pm_runtime_put_sync(wdev->dev);
> + if (early_disable)
> + pm_runtime_put_sync(wdev->dev);

Again, I think this should be
if (!wdev->omap_wdt_users)

and you should actually detect if the watchdog is running or not.

>
> return 0;
> }
> --
> 1.9.1
>
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