| Message ID | 20181107194602.7209-1-wsa+renesas@sang-engineering.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Geert Uytterhoeven |
| Headers | show |
| Series | [v2] watchdog: renesas_wdt: don't set divider while watchdog is running | expand |
Hi Wolfram, Thank you for your patch! > Subject: [PATCH v2] watchdog: renesas_wdt: don't set divider while watchdog is running > > 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@sang-engineering.com> Reviewed-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com> > --- > > 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 Renesas Electronics Europe Ltd, Dukes Meadow, Millboard Road, Bourne End, Buckinghamshire, SL8 5FH, UK. Registered in England & Wales under Registered No. 04586709.
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@sang-engineering.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> > --- > > 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 >
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();
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@sang-engineering.com> --- 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(-)