From: Anson Huang <anson.huang@nxp.com>
To: Guenter Roeck <linux@roeck-us.net>,
"wim@linux-watchdog.org" <wim@linux-watchdog.org>,
"shawnguo@kernel.org" <shawnguo@kernel.org>,
"s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
"kernel@pengutronix.de" <kernel@pengutronix.de>,
"festevam@gmail.com" <festevam@gmail.com>,
"linux-watchdog@vger.kernel.org" <linux-watchdog@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: dl-linux-imx <linux-imx@nxp.com>
Subject: RE: [PATCH V2 1/2] watchdog: imx7ulp: Strictly follow the sequence for wdog operations
Date: Wed, 29 Jul 2020 05:02:33 +0000 [thread overview]
Message-ID: <DB3PR0402MB3916B38E7DA20A35403F5B1EF5700@DB3PR0402MB3916.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <DB3PR0402MB3916C412DE1E83A2D40B2341F5700@DB3PR0402MB3916.eurprd04.prod.outlook.com>
Hi, Guenter
> Subject: RE: [PATCH V2 1/2] watchdog: imx7ulp: Strictly follow the sequence
> for wdog operations
>
> Hi, Guenter
>
>
> > Subject: Re: [PATCH V2 1/2] watchdog: imx7ulp: Strictly follow the
> > sequence for wdog operations
> >
> > On 7/28/20 7:20 PM, Anson Huang wrote:
> > > According to reference manual, the i.MX7ULP WDOG's operations should
> > > follow below sequence:
> > >
> > > 1. disable global interrupts;
> > > 2. unlock the wdog and wait unlock bit set; 3. reconfigure the wdog
> > > and wait for reconfiguration bit set; 4. enabel global interrupts.
> > >
> > > Strictly follow the recommended sequence can make it more robust.
> > >
> > > Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
> > > ---
> > > Changes since V1:
> > > - use readl_poll_timeout_atomic() instead of usleep_ranges() since
> > > IRQ is
> > disabled.
> > > ---
> > > drivers/watchdog/imx7ulp_wdt.c | 29 +++++++++++++++++++++++++++++
> > > 1 file changed, 29 insertions(+)
> > >
> > > diff --git a/drivers/watchdog/imx7ulp_wdt.c
> > > b/drivers/watchdog/imx7ulp_wdt.c index 7993c8c..7d2b12e 100644
> > > --- a/drivers/watchdog/imx7ulp_wdt.c
> > > +++ b/drivers/watchdog/imx7ulp_wdt.c
> > > @@ -5,6 +5,7 @@
> > >
> > > #include <linux/clk.h>
> > > #include <linux/io.h>
> > > +#include <linux/iopoll.h>
> > > #include <linux/kernel.h>
> > > #include <linux/module.h>
> > > #include <linux/of.h>
> > > @@ -36,6 +37,7 @@
> > > #define DEFAULT_TIMEOUT 60
> > > #define MAX_TIMEOUT 128
> > > #define WDOG_CLOCK_RATE 1000
> > > +#define WDOG_WAIT_TIMEOUT 10000
> > >
> > > static bool nowayout = WATCHDOG_NOWAYOUT;
> > module_param(nowayout,
> > > bool, 0000); @@ -48,17 +50,31 @@ struct imx7ulp_wdt_device {
> > > struct clk *clk;
> > > };
> > >
> > > +static inline void imx7ulp_wdt_wait(void __iomem *base, u32 mask) {
> > > + u32 val = readl(base + WDOG_CS);
> > > +
> > > + if (!(val & mask))
> > > + WARN_ON(readl_poll_timeout_atomic(base + WDOG_CS, val,
> > > + val & mask, 0,
> > > + WDOG_WAIT_TIMEOUT));
> >
> > I am not a friend of WARN_ON, especially in situations like this.
> > Please explain why this is needed, and why a return of -ETIMEDOUT is
> > not feasible.
>
> OK, I will use return value of -ETIMEOUT and handle it in the caller.
After a further look, some of the imx7ulp_wdt_wait () callers are void function, so if want
to handle the return value, all those functions return type need to be changed. And, when
the return value is -ETIMEDOUT, the ONLY action is to print out some error message
for these void function, need to use pr_err() due to no dev pointer available, so
do you think it is acceptable to just replace the WARN_ON with pr_err() as below?
+ if (!(val & mask)) {
+ if (readl_poll_timeout_atomic(base + WDOG_CS, val,
+ val & mask, 0,
+ WDOG_WAIT_TIMEOUT))
+ pr_err("wdog wait timeout, mask 0x%x\n", mask);
+ }
Thanks,
Anson
next prev parent reply other threads:[~2020-07-29 5:02 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-29 2:20 [PATCH V2 1/2] watchdog: imx7ulp: Strictly follow the sequence for wdog operations Anson Huang
2020-07-29 2:20 ` [PATCH V2 2/2] watchdog: imx7ulp: Watchdog should continue running for wait/stop mode Anson Huang
2020-07-29 4:15 ` [PATCH V2 1/2] watchdog: imx7ulp: Strictly follow the sequence for wdog operations Guenter Roeck
2020-07-29 4:50 ` Anson Huang
2020-07-29 5:02 ` Anson Huang [this message]
2020-07-29 14:55 ` Guenter Roeck
2020-07-29 15:13 ` Anson Huang
2020-07-29 14:13 ` Guenter Roeck
2020-07-29 14:17 ` Anson Huang
2020-07-29 15:15 ` Guenter Roeck
2020-07-29 15:32 ` Anson Huang
2020-07-29 15:49 ` Guenter Roeck
2020-07-30 2:04 ` Anson Huang
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