On Wed, Nov 07, 2018 at 08:46:02PM +0100, Wolfram Sang wrote:
> The datasheet says we must stop the timer before changing the clock
> divider. This can happen when the restart handler is called while the
> watchdog is running.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
>
> Change since V1: reworded commit message.
>
> I sent V1 back then when it was more a recommendation of the datasheet to do it
> like this. But meanwhile the code changed, so we actually need to do it.
>
> drivers/watchdog/renesas_wdt.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
> index 0d74c3e48979..55c9eb6c6e51 100644
> --- a/drivers/watchdog/renesas_wdt.c
> +++ b/drivers/watchdog/renesas_wdt.c
> @@ -74,12 +74,17 @@ static int rwdt_init_timeout(struct watchdog_device *wdev)
> static int rwdt_start(struct watchdog_device *wdev)
> {
> struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
> + u8 val;
>
> pm_runtime_get_sync(wdev->parent);
>
> - rwdt_write(priv, 0, RWTCSRB);
> - rwdt_write(priv, priv->cks, RWTCSRA);
> + /* Stop the timer before we modify any register */
> + val = readb_relaxed(priv->base + RWTCSRA) & ~RWTCSRA_TME;
> + rwdt_write(priv, val, RWTCSRA);
> +
> rwdt_init_timeout(wdev);
> + rwdt_write(priv, priv->cks, RWTCSRA);
> + rwdt_write(priv, 0, RWTCSRB);
>
> while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
> cpu_relax();
> --
> 2.11.0
>
