Lenovo Yoga C630 as most of the other WoA devices stores RTC offset in
the UEFI variable. Add corresponding property to the RTC device in order
to make RTC driver wait for UEFI variables to become available and then
read offset value from the corresponding variable.

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
---
 arch/arm64/boot/dts/qcom/pm8998.dtsi                 | 2 +-
 arch/arm64/boot/dts/qcom/sdm850-lenovo-yoga-c630.dts | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/qcom/pm8998.dtsi b/arch/arm64/boot/dts/qcom/pm8998.dtsi
index 3ecb330590e59a6640f833a0bf4d2c62f40de17d..50b41942b06cf1a3f43f9c754b3bf2e1eaa4d353 100644
--- a/arch/arm64/boot/dts/qcom/pm8998.dtsi
+++ b/arch/arm64/boot/dts/qcom/pm8998.dtsi
@@ -101,7 +101,7 @@ pm8998_adc_tm: adc-tm@3400 {
 			status = "disabled";
 		};
 
-		rtc@6000 {
+		pm8998_rtc: rtc@6000 {
 			compatible = "qcom,pm8941-rtc";
 			reg = <0x6000>, <0x6100>;
 			reg-names = "rtc", "alarm";
diff --git a/arch/arm64/boot/dts/qcom/sdm850-lenovo-yoga-c630.dts b/arch/arm64/boot/dts/qcom/sdm850-lenovo-yoga-c630.dts
index 8ef6db3be6e3dffe4ec819288193a183b32db8e8..c0c007ce8682cacd1cbfe816ddb975c0a099ac89 100644
--- a/arch/arm64/boot/dts/qcom/sdm850-lenovo-yoga-c630.dts
+++ b/arch/arm64/boot/dts/qcom/sdm850-lenovo-yoga-c630.dts
@@ -592,6 +592,10 @@ sw_edp_1p2_en: pm8998-gpio9-state {
 	};
 };
 
+&pm8998_rtc {
+	qcom,uefi-rtc-info;
+};
+
 &qup_i2c10_default {
 	drive-strength = <2>;
 	bias-disable;

-- 
2.39.5

On Wed, Jun 25, 2025 at 01:53:27AM +0300, Dmitry Baryshkov wrote:
> Lenovo Yoga C630 as most of the other WoA devices stores RTC offset in
> the UEFI variable. Add corresponding property to the RTC device in order
> to make RTC driver wait for UEFI variables to become available and then
> read offset value from the corresponding variable.

This is not a fix so please drop that word from Subject.

I'd also expect you to mention that the RTC would be heavily crippled on
this machine as the efi variables cannot be updated.

Is there even a UEFI setup setting for this so that users that have
blown away Windows can ever set the time (which may become totally off
due to drift)?

I'm still not convinced that this is something we want, especially since
you could have a fully functional RTC by providing an SDAM offset
instead like we do on the sc8280xp CRD.

Johan

On Thu, Jun 26, 2025 at 12:16:49PM +0200, Johan Hovold wrote:
> On Wed, Jun 25, 2025 at 01:53:27AM +0300, Dmitry Baryshkov wrote:
> > Lenovo Yoga C630 as most of the other WoA devices stores RTC offset in
> > the UEFI variable. Add corresponding property to the RTC device in order
> > to make RTC driver wait for UEFI variables to become available and then
> > read offset value from the corresponding variable.
> 
> This is not a fix so please drop that word from Subject.

ack

> 
> I'd also expect you to mention that the RTC would be heavily crippled on
> this machine as the efi variables cannot be updated.

ack

> 
> Is there even a UEFI setup setting for this so that users that have
> blown away Windows can ever set the time (which may become totally off
> due to drift)?

There is a UEFI setup UI.

> I'm still not convinced that this is something we want, especially since
> you could have a fully functional RTC by providing an SDAM offset
> instead like we do on the sc8280xp CRD.

No, I don't want to go that way.

-- 
With best wishes
Dmitry