Re: [PATCH 19/24] rtc: pm8xxx: add support for uefi offset

Alexandre Belloni
2023-01-27T15:59:58Z

On 27/01/2023 16:26:26+0100, Johan Hovold wrote:
> On Fri, Jan 27, 2023 at 04:19:18PM +0100, Alexandre Belloni wrote:
> > On 26/01/2023 15:20:52+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 the
> > > driver can take into account.
> > >
> > > Add support for storing a 32-bit offset from the GPS time epoch in a
> > > UEFI variable so that the RTC time can be set on such platforms.
> > >
> >
> > Why are you using the GPS epoch? This seems pretty random.
>
> Tell that to the Qualcomm firmware team. ;)
>
> Perhaps I could have made it more clear, but this is the format that the
> firmware uses so Linux is not free to pick a different base here (or
> time would differ ten years between UEFI/Windows and Linux).

I expected this answer so please add this to the commit message, this
will be the fifth epoch we ave to handle then...

>
> > > 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.
>
> Johan

--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering