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

[Akashdeep Kaur <a-kaur@ti.com>]

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@ti.com>
>> ---
>>
>> 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);
>