Re: [PATCH 0/4] regulator: qcom-rpmh: Support RPMH address reads and use it for rpmh-regulators

[Dmitry Baryshkov]

On Tue, Apr 07, 2026 at 03:44:57AM +0530, Kamal Wadhwa wrote:
> This patch series adds a new `rpmh_read()` API to allow reading RPMH
> addresses. Using this API enhances the RPMH regulator driver by adding
> new `get_status()` callback to reflect the regulator status and also
> readback the voltage/bypass/mode settings as they have been applied by
> APPS during the bootloader stage, so regulator framework can get them
> via `get_mode`, `get_bypass` & `get_voltage_selector` callbacks during
> regulator registration.
> 
> This is needed because currently regulator framework does a unnecessary
> write with `min-microvolt` DT setting for all the RPMH regulators during
> regulator registration, because the first time after boot the value is
> seen as -ENOTRECOVERABLE, as there is no option to read these regulator
> settings.
> 
> With this change this unnecessary write can be avoided and regulator
> framework gets a sense of the initial state set during the bootloader
> stage for all regulator settings.
> 
> NOTE - During discussion on the v2 series - PATCH 3/4, reviewer had
> inquired about possible need for the use of the sync_state() to handle the
> "multiple" client case - for maintaining the regulator settings till all
> the clients are probed.
> 
> This case was not covered in my previous series and had originally planned
> to do that series seperately. But after the discussion decided to merge
> the 2 series as it seemed this would be a better approach. But after
> working on sync_state change. I realized a basic issue with using
> sync_state() for regulators - that its per-driver and not per-regulator
> resource. But we needed a sync_state callback for each regulator seperately.
> 
> I had been experimenting with few ideas but seems its going to need more
> time for me to close on the eqvivalent solution that has per-regulator
> sync_state or something to that effect. So I thought to close on this 
> series and attend to that seperately.
> 
> Signed-off-by: Kamal Wadhwa <kamal.wadhwa@xxxxxxxxxxxxxxxx>
> ---
> Changes in v3:

If this is v3, why is not marked as such?

> - Removed "bypass_supported" as that is not needed for regulators
>   that don't have set_bypass implemented, as pointed by Dmitry.
> - Handled the corner case where the mode/bypass setting is read 0, but
>   its unclear if the register has been set to 0 or its un-accessed.
> - Dropped `convert_mode_to_status()` and use the `regulator_mode_to_status()`
>   instead.
> - Refactored some code to simplify the `status` update after every
>   enable/mode/bypass setting change.
> - Corrected subject line of all patches to have `regulator: qcom-rpmh:`
>   for all the `qcom-rpmh-regulator.c` file changes, as pointed by Bjorn.
> - Re-ordered the series to have the `rpmh.c` driver patches first and
>   than `qcom-rpmh-regulator.c` driver patches as asked by Bjorn.
> - In the BOB5 bypass fix patch (PATCH 1/4 in previous series), added
>   the fixes commit#, as it was missed earlier.
> - In the rpmh driver change(PATCH 2/4 in previous series), modified
>   commit wording and removed linked as suggested by reviewer.
> - Fixed kernel test robot issues and other formatting issues in
>   PATCH 3/4 of last series.
> - Corrected the checkpatch error fix PATCH 4/4 to keep to only
>   one error in comment section which existed prior to this
>   series.
> - Link to v2: https://lore.kernel.org/all/20251022-add-rpmh-read-support-v2-0-5c7a8e4df601@xxxxxxxxxxxxxxxx/
> 
> 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@xxxxxxxxxx/
>   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@xxxxxxxxxxxxxxxx
> 
> Signed-off-by: Kamal Wadhwa <kamal.wadhwa@xxxxxxxxxxxxxxxx>
> 
> ---
> Kamal Wadhwa (3):
>       regulator: qcom-rpmh: Fix PMIC5 BOB bypass mode handling
>       regulator: qcom-rpmh: readback voltage/bypass/mode/status set during bootup
>       regulator: qcom-rpmh: Fix coding style issues
> 
> Maulik Shah (1):
>       soc: qcom: rpmh: Add support to read back resource settings
> 
>  drivers/regulator/qcom-rpmh-regulator.c | 186 +++++++++++++++++++++++++++++++-
>  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, 245 insertions(+), 8 deletions(-)
> ---
> base-commit: bd0f139e5fc11182777b81cefc3893ea508544ec
> change-id: 20260407-read-rpmh-v3-821188eae030
> 
> Best regards,
> -- 
> Kamal Wadhwa <kamal.wadhwa@xxxxxxxxxxxxxxxx>
> 

-- 
With best wishes
Dmitry