4.20-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit e990e12741877e9bfac402ca468f4007a75f6e2a ]
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 Reviewed-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Wim Van Sebroeck wim@linux-watchdog.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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();