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SubjectRe: [PATCH] watchdog: imx2_wdt: restore previous timeout after suspend+resume
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On 12/29/2017 05:59 AM, Martin Kaiser wrote:
> When the watchdog device is suspended, its timeout is set to the maximum
> value. During resume, the previously set timeout should be restored.
> This does not work at the moment.
>
> The suspend function calls
>
> imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
>
> and resume reverts this by calling
>
> imx2_wdt_set_timeout(wdog, wdog->timeout);
>
> However, imx2_wdt_set_timeout() updates wdog->timeout. Therefore,
> wdog->timeout is set to IMX2_WDT_MAX_TIME when we enter the resume
> function.
>
> Fix this by setting wdog->timeout to the previous value at the end of
> the suspend function. This manual update makes wdog->timeout different
> from the actual setting in the hardware. This should be ok in our case
> as kernel code is not running while we're suspended.
>
> Signed-off-by: Martin Kaiser <martin@kaiser.cx>
> Cc: stable@vger.kernel.org

That works, though it is a bit hackish. Better would be to have a function
such as _imx2_wdt_set_timeout() which doesn't actually update wdt->timeout
and could be called from all the other places doing the same.
Separate patch, maybe.

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
> drivers/watchdog/imx2_wdt.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
> index 4874b0f..66efcc0 100644
> --- a/drivers/watchdog/imx2_wdt.c
> +++ b/drivers/watchdog/imx2_wdt.c
> @@ -368,6 +368,7 @@ static int imx2_wdt_suspend(struct device *dev)
> {
> struct watchdog_device *wdog = dev_get_drvdata(dev);
> struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
> + unsigned int resume_timeout = wdog->timeout;
>
> /* The watchdog IP block is running */
> if (imx2_wdt_is_running(wdev)) {
> @@ -377,6 +378,7 @@ static int imx2_wdt_suspend(struct device *dev)
>
> clk_disable_unprepare(wdev->clk);
>
> + wdog->timeout = resume_timeout;
> return 0;
> }
>
>

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