[PATCH] arm64: dts: qcom: sc8280xp-blackrock: switch to uefi rtc offset

Jens Glathe via B4 Relay
2026-05-01T09:11:40Z

From: Jens Glathe <jens.glathe@oldschoolsolutions.biz>

On many Qualcomm platforms the PMIC RTC control and time registers are
read-only so that the RTC time can not be updated. Instead an offset
needs be stored in some machine-specific non-volatile memory, which a
driver can take into account.

On platforms where the offset is stored in a Qualcomm specific UEFI
variable the variables are also accessed in a non-standard way, which
means that the OS cannot assume that the variable service is available
by the time the RTC driver probes.

Use the new 'qcom,uefi-rtc-info' property to indicate that the offset is
stored in a UEFI variable so that the OS can determine whether to wait
for it to become available.

[1]: https://lore.kernel.org/r/20250423075143.11157-4-johan+linaro@kernel.org

Fixes: 16a7fed11714 ("arm64: dts: qcom: sc8280xp-blackrock: dt definition for WDK2023")

Signed-off-by: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
---
This is the first of a small series of incremental updates for the
Microsoft Windows Dev Kit 2023 (sc8280xp-blackrock / Project Volterra).

Subsequent patches will address:
- USB-C DP altmode support on the rear port (USB0)
- Audio on all three DisplayPort-capable connectors
- A few other cleanups cherry-picked from the Lenovo X13s

The goal is to keep changes small and reviewable.

base-commit: b9303e6bff706758c167af686b5315ad00233bf8
---
arch/arm64/boot/dts/qcom/sc8280xp-microsoft-blackrock.dts | 11 +----------
1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/sc8280xp-microsoft-blackrock.dts b/arch/arm64/boot/dts/qcom/sc8280xp-microsoft-blackrock.dts
index 00bbeeef6f14dd89de506e33742f8f73435ac021..3dc3d7ae928d0a509c564a32908e33f5ca934c98 100644
--- a/arch/arm64/boot/dts/qcom/sc8280xp-microsoft-blackrock.dts
+++ b/arch/arm64/boot/dts/qcom/sc8280xp-microsoft-blackrock.dts
@@ -763,20 +763,11 @@ &pmk8280_pon_resin {
};

&pmk8280_rtc {
- nvmem-cells = <&rtc_offset>;
- nvmem-cell-names = "offset";
+ qcom,uefi-rtc-info;

status = "okay";
};

-&pmk8280_sdam_6 {
- status = "okay";
-
- rtc_offset: rtc-offset@bc {
- reg = <0xbc 0x4>;
- };
-};
-
&pmk8280_vadc {
channel@144 {
reg = <PM8350_ADC7_AMUX_THM1_100K_PU(1)>;

---
base-commit: b9303e6bff706758c167af686b5315ad00233bf8
change-id: 20260501-blackrock-rtc-2efe7ae9ae64

Best regards,
--
Jens Glathe <jens.glathe@oldschoolsolutions.biz>