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

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Message-ID: <eivl52lqeurk3bcklnoqjnnfqv3tgmkh4ehf6jchbnf3j44ads@oogqwpvkahhp>
Date: Wed, 22 Oct 2025 16:02:00 -0500
From: Bjorn Andersson <andersson@...nel.org>
To: Kamal Wadhwa <kamal.wadhwa@....qualcomm.com>
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 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.

> 
> 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.

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>
>