Re: [PATCH] rtc: ti-k3: Add support to resume from IO DDR low power mode

[Akashdeep Kaur]

Hi Vignesh,

On 13/03/26 13:53, Vignesh Raghavendra wrote:
> On 11/03/26 12:32, Akashdeep Kaur wrote:
> > During IO DDR low power mode, the RTC IP is reset and loses its
> > register configuration.
>
> > The DDR memory still preserves all driver states
> > (reference counts, software context).
>
> That's the definition of Suspend to RAM
>
> > System clocks are saved and restored
> > by Device Manager (DM) firmware during the resume sequence.
>
> Not relevant for this patch in particular.
>
> > Add support to reconfigure the RTC IP registers in resume handler only if
> > resume hook is called during IO DDR low power mode resume.
>
> Above all is probably bit too verbose. Below text is all thats needed:
>
> Restore the RTC HW context which may be lost when system enters certain
> low power mode (IO+DDR mode). Check if the RTC registers are locked
> which would indicate loss of context (reset) and restore the context as
> needed.

Updated the commit message as suggested.

Regards,
Akashdeep Kaur
> > Signed-off-by: Akashdeep Kaur <a-kaur@xxxxxx>
> > ---
> >
> > Tested deep sleep with rtcwake after IO DDR resume on AM62P-SK.
> >
> > ---
> >   drivers/rtc/rtc-ti-k3.c | 10 +++++++++-
> >   1 file changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/rtc/rtc-ti-k3.c b/drivers/rtc/rtc-ti-k3.c
> > index ec759d8f7023..e801f5b9d757 100644
> > --- a/drivers/rtc/rtc-ti-k3.c
> > +++ b/drivers/rtc/rtc-ti-k3.c
> > @@ -640,10 +640,18 @@ static int __maybe_unused ti_k3_rtc_suspend(struct device *dev)
> >   static int __maybe_unused ti_k3_rtc_resume(struct device *dev)
> >   {
> >   	struct ti_k3_rtc *priv = dev_get_drvdata(dev);
> > +	int ret = 0;
> > +
> > +	if (k3rtc_check_unlocked(priv)) {
> > +		/* RTC locked implies low power mode exit where RTC loses context */
> > +		ret = k3rtc_configure(dev);
> > +		if (ret)
> > +			return ret;
> > +	}
> >   
> >   	if (device_may_wakeup(dev))
> >   		disable_irq_wake(priv->irq);
> > -	return 0;
> > +	return ret;
> >   }
> >   
> >   static SIMPLE_DEV_PM_OPS(ti_k3_rtc_pm_ops, ti_k3_rtc_suspend, ti_k3_rtc_resume);