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.hu...@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
