linux-kernel - Re: [PATCH v2 0/4] Add support to read RPMH regulator settings

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Message-ID: <20251023103449.vr6yccqua5gsgck4@hu-kamalw-hyd.qualcomm.com>
Date: Thu, 23 Oct 2025 16:04:49 +0530
From: Kamal Wadhwa <kamal.wadhwa@....qualcomm.com>
To: Bjorn Andersson <andersson@...nel.org>
Cc: Konrad Dybcio <konradybcio@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Maulik Shah <maulik.shah@....qualcomm.com>,
        David Collins <david.collins@....qualcomm.com>
Subject: Re: [PATCH v2 0/4] Add support to read RPMH regulator settings

On Wed, Oct 22, 2025 at 04:02:00PM -0500, Bjorn Andersson wrote:
> On Wed, Oct 22, 2025 at 02:38:52AM +0530, Kamal Wadhwa wrote:
> > This patch series adds a new `rpmh_read()` API to allow reading RPMH
> > addresses. Also, using this new API, enhances the RPMH regulator driver
> > get_regulator* APIs like `get_regulator_sel()`, `get_mode()` and
> > `get_status()` to allow reading voltage/mode/enable setting from H/W.
> > 
> > This is needed because current design has a limitation - regulator
> > framework can only get the cached values from the last voltage set
> > operation. Because of this right after bootup a `get_voltage_sel()`
> > from regulator framework will return -ENOTRECOVERABLE error, causing
> > regulator framework to trigger an unnecessary `set_voltage_sel()` call
> > with the `min_uV` value specified in the regulator's device tree
> > settings, which can cause issues for consumers like the display and
> > UFS that require a consistent voltage setting from the bootloader
> > state until their drivers are probed.
> > 
> > With this change regulator framework will get the regulator voltage
> > and other settings, as configured during bootloader stage, avoiding
> > unnecessary voltage adjustments and maintaining consistent power
> > settings across the transition from bootloader to kernel.
> > 
> > Besides this feature this series also fixes:-
> > - An existing issue with the BOB5 pass code value. This is needed
> >   by `get_status()`.
> > - Code format/style related errors reported by checkpatch.pl.
> > 
> > Signed-off-by: Kamal Wadhwa <kamal.wadhwa@....qualcomm.com>
> > ---
> > Changes in v2:
> > - Fixed the BOB bypass mode handling (existing issue in current driver).
> >   This was needed for `get_status()` implementation.
> > - Implemented `get_status()` callback.
> > - Callbacks for `is_enabled()` & `get_mode()` will now be used as-is
> >   ie. v1 changes reverted.
> > - Bootstapped the read values for `mode` and `status` in probe, based on
> >   comments recieved from reviewer. 
> > - Callback for `get_voltage_sel()` has been modified to handle cases
> >   where read voltage is out-of-range defined in the regulator DT settings,
> >   this is needed to ensure backward compatibilty. Regulator probes may
> >   fail otherwise for some older targets.
> > - This patch is rebased & tested on:
> >    https://lore.kernel.org/all/176070318151.57631.15443673679580823321.b4-ty@kernel.org/
> >   to avoid any merge issues.
> > - Fixed code style issues reported by checkpatch.pl script. 
> > - Link to v1: https://lore.kernel.org/r/20250623-add-rpmh-read-support-v1-0-ae583d260195@oss.qualcomm.com
> > 
> > ---
> > Kamal Wadhwa (3):
> >       regulator: rpmh-regulator: Fix PMIC5 BOB bypass mode handling
> >       regulator: qcom-rpmh: Add support to read regulator settings
> >       regulators: qcom-rpmh-regulator: Fix coding style issues
> 
> These three changes all changes the same one file, but you have 3
> different subject prefixes. This is just sloppy, please follow other
> changes to this one file.

sorry will take care of this in the next version.

> 
> > 
> > Maulik Shah (1):
> >       soc: qcom: rpmh: Add support to read back resource settings
> 
> I'd like to merge this through the soc tree, please put it first in the
> series to simplify this.

Ok will do that in next series.

> 
> Regards,
> Bjorn
> 
> > 
> >  drivers/regulator/qcom-rpmh-regulator.c | 184 +++++++++++++++++++++++++++++++-
> >  drivers/soc/qcom/rpmh-rsc.c             |  13 ++-
> >  drivers/soc/qcom/rpmh.c                 |  47 +++++++-
> >  include/soc/qcom/rpmh.h                 |   5 +
> >  include/soc/qcom/tcs.h                  |   2 +
> >  5 files changed, 241 insertions(+), 10 deletions(-)
> > ---
> > base-commit: fe45352cd106ae41b5ad3f0066c2e54dbb2dfd70
> > change-id: 20250623-add-rpmh-read-support-3288f83cc20a
> > 
> > Best regards,
> > -- 
> > Kamal Wadhwa <kamal.wadhwa@....qualcomm.com>
> >