Re: [RFC 18/24] dt-bindings: rtc: qcom-pm8xxx: add uefi-variable offset

Rob Herring
2023-01-30T18:49:59Z

On Thu, Jan 26, 2023 at 03:20:51PM +0100, Johan Hovold wrote:
> 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.
>
> Add a 'qcom,uefi-rtc-info' boolean flag which indicates that the RTC
> offset is stored in a Qualcomm specific UEFI variable so that the RTC
> time can be updated on such platforms.
>
> The UEFI variable is
>
> 882f8c2b-9646-435f-8de5-f208ff80c1bd-RTCInfo
>
> and holds a 12-byte structure where the first four bytes is a GPS time
> offset in little-endian byte order.

Can't you just try to read the UEFI variable and use it if that
succeeds?

I don't like this in DT because what if lots of devices start storing
lots of things in vendor specific UEFI variables. It doesn't scale.

Rob