Re: [PATCH v2 2/2] rtc: pcf2127: Run a OTP refresh if not done before

[Philipp Rosenberger]

On 14.01.21 09:06, Uwe Kleine-König wrote:
> On Wed, Jan 13, 2021 at 12:27:42PM +0100, Philipp Rosenberger wrote:
> > The datasheet of the PCF2127 states,it is recommended to process an OTP
>
> s/,/, /

ACK

> > refresh once the power is up and the oscillator is operating stable. The
> > OTP refresh takes less than 100 ms to complete.
> >
> > Signed-off-by: Philipp Rosenberger <p.rosenberger@xxxxxxxxxx>
> > ---
> >   drivers/rtc/rtc-pcf2127.c | 16 ++++++++++++++++
> >   1 file changed, 16 insertions(+)
> >
> > diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
> > index 378b1ce812d6..ca56dba64e79 100644
> > --- a/drivers/rtc/rtc-pcf2127.c
> > +++ b/drivers/rtc/rtc-pcf2127.c
> > @@ -58,6 +58,9 @@
> >   #define PCF2127_REG_ALARM_DM		0x0D
> >   #define PCF2127_REG_ALARM_DW		0x0E
> >   #define PCF2127_BIT_ALARM_AE			BIT(7)
> > +/* CLKOUT control register */
> > +#define PCF2127_REG_CLKOUT		0x0f
> > +#define PCF2127_BIT_CLKOUT_OTPR			BIT(5)
> >   /* Watchdog registers */
> >   #define PCF2127_REG_WD_CTL		0x10
> >   #define PCF2127_BIT_WD_CTL_TF0			BIT(0)
> > @@ -630,6 +633,19 @@ static int pcf2127_probe(struct device *dev, struct regmap *regmap,
> >   		dev_warn(dev, "Watchdog and alarm functions might not work properly\n");
> >   	}
> >   
> > +	/*
> > +	 * Set the OTP refresh bit unconditionally. If an OTP refresh was
> > +	 * already done the bit is already set and will not rerun the refresh
> > +	 * operation.
> > +	 */
> > +	ret = regmap_set_bits(pcf2127->regmap, PCF2127_REG_CLKOUT,
> > +			      PCF2127_BIT_CLKOUT_OTPR);
> > +	if (ret < 0) {
> > +		dev_err(dev, "%s: OTP refresh (clkout_ctrl) failed.\n", __func__);
> > +		return ret;
> > +	}
> > +	msleep(100);
>
> This unconditional sleep isn't so nice. Maybe it makes sense to only do
> this when the chip reports a power loss?

Right, will change that

> Best regards
> Uwe

Best Regards,
Philipp