| Message ID | 20220825083256.14565-3-alice.guo@oss.nxp.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | watchdog: imx7ulp_wdt: update i.MX7ULP WDOG timer driver | expand |
On Thu, Aug 25, 2022 at 04:32:51PM +0800, Alice Guo (OSS) wrote: > From: Jacky Bai <ping.bai@nxp.com> > > When reconfiguring the WDOG Timer of i.MX7ULP, there is a certain > probability causes it to reset. The reason is that the CMD32EN of the > WDOG Timer of i.MX7ULP is disabled in bootloader. The unlock sequence > are two 16-bit writes to the CNT register within 16 bus clocks. Adding > mb() is to guarantee that two 16-bit writes are finished within 16 bus > clocks. Memory barriers cannot be added between these two 16-bit writes > so that writel_relaxed is used. > > Suggested-by: Ye Li <ye.li@nxp.com> > Signed-off-by: Jacky Bai <ping.bai@nxp.com> > Signed-off-by: Alice Guo <alice.guo@nxp.com> > Reviewed-by: Ye Li <ye.li@nxp.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> > --- > > Changes for v2: > - add the reason why memory barriers are added for unlock sequence in commit log > > drivers/watchdog/imx7ulp_wdt.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/watchdog/imx7ulp_wdt.c b/drivers/watchdog/imx7ulp_wdt.c > index 014f497ea0dc..b8ac0cb04d2f 100644 > --- a/drivers/watchdog/imx7ulp_wdt.c > +++ b/drivers/watchdog/imx7ulp_wdt.c > @@ -179,9 +179,13 @@ static int imx7ulp_wdt_init(void __iomem *base, unsigned int timeout) > int ret; > > local_irq_disable(); > + > + mb(); > /* unlock the wdog for reconfiguration */ > writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT); > writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT); > + mb(); > + > ret = imx7ulp_wdt_wait(base, WDOG_CS_ULK); > if (ret) > goto init_out; > -- > 2.17.1 >
diff --git a/drivers/watchdog/imx7ulp_wdt.c b/drivers/watchdog/imx7ulp_wdt.c index 014f497ea0dc..b8ac0cb04d2f 100644 --- a/drivers/watchdog/imx7ulp_wdt.c +++ b/drivers/watchdog/imx7ulp_wdt.c @@ -179,9 +179,13 @@ static int imx7ulp_wdt_init(void __iomem *base, unsigned int timeout) int ret; local_irq_disable(); + + mb(); /* unlock the wdog for reconfiguration */ writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT); writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT); + mb(); + ret = imx7ulp_wdt_wait(base, WDOG_CS_ULK); if (ret) goto init_out;