From: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
To: Luke Macken <luke@phorex.org>,
andersson@kernel.org, konradybcio@kernel.org
Cc: abelvesa@kernel.org, robh@kernel.org, krzk+dt@kernel.org,
conor+dt@kernel.org, srinivas.kandagatla@oss.qualcomm.com,
linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: dts: qcom: mahua-t14s: store the RTC offset in SDAM
Date: Wed, 21 Oct 2026 12:39:11 +0200 [thread overview]
Message-ID: <dd641bbb-6012-4d6b-9bd6-5dbf4cd849dc@oss.qualcomm.com> (raw)
In-Reply-To: <20261016232528.4012876-1-luke@phorex.org>
On 10/17/26 1:25 AM, Luke Macken wrote:
> The PMIC RTC registers on the Lenovo ThinkPad T14s Gen 7 are read-only,
> so an offset needs to be stored in machine-specific non-volatile memory
> which the RTC driver can take into account when reading or updating the
> time.
>
> The firmware on this machine does not provide the RTCInfo UEFI variable
> that other Glymur based machines use for this purpose, so, as on
> sc8280xp-crd and the QCS8550 boards, reserve four bytes in one of the
> PMIC SDAM blocks to hold the RTC offset. SDAM 2 on PMK8850 is 128 bytes
> and its last word is not used by the firmware.
Bold claim, there's a lot of firmware!
On Glymur machines, the RTC is coordinated through SoCCP. We're working
on providing an interface to that.
[...]
> Note for reviewers: Qualcomm's "rtc: Add Qualcomm PMIC RTC-GLINK support
> for Glymur" (August 2026) would move the RTC behind the charger firmware
> on these machines, but it has not been resubmitted and needs firmware
> that at least the ThinkPad does not ship yet. This patch uses the
> existing rtc-pm8xxx nvmem offset mechanism in the meantime and does not
> conflict with that work.
There's another access mechanism to pmic-glink that may unblock this.
Konrad
prev parent reply other threads:[~2026-10-21 10:39 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-16 23:25 Luke Macken
2026-10-21 10:39 ` Konrad Dybcio [this message]
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