Re: [PATCH 0/4] thermal: Introduce Qualcomm Thermal Mitigation Device support

[Manivannan Sadhasivam <mani@kernel.org>]

On Sun, Oct 01, 2023 at 06:26:14PM +0100, Caleb Connolly wrote:
> 
> 
> On 01/10/2023 16:57, Manivannan Sadhasivam wrote:
> > On Fri, Sep 29, 2023 at 05:16:16PM +0100, Caleb Connolly wrote:
> > > The Thermal Mitigation Device (TMD) Service is a QMI service that runs
> > > on remote subsystems (the modem and DSPs) on Qualcomm SoCs.
> > > It exposes various mitigations including passive thermal controls and
> > > rail voltage restrictions.
> > > 
> > > This series introduces support for exposing TMDs as cooling devices
> > > in the kernel through the thermal framework, using the QMI interface.
> > > 
> > > Each TMD client is described as a child of the remoteproc node in
> > > devicetree. With subnodes for each control.
> > > 
> > 
> > Daniel expressed concerns in the past aganist representing TMD driver as a
> > cooling device since it is not tied to thermal zones and the governors cannot
> > use it. Instead he suggested to represent it as a powercap device with thermal
> > constraints.
> 
> Hi Mani,
> 
> Forgive me as I'm not yet super familiar with the thermal subsystem.
> 
> As I understand it, the DT layout here enables each control to be referenced
> under the thermal zones, at least this is the approach taken in CAF 4.9.
> 
> Maybe I don't quite understand what you mean, are you saying that using
> thermal zones is the wrong approach?

Thermal framework expects each thermal zone represented in DT to have atleast
one corresponding thermal sensor defined using "thermal-sensors" property. But
with TMD, there is no thermal sensor AFAIK.

> > 
> > So please look into that approach.
> 
> Any recommended reading? Or drivers I can use as a reference?
> 

drivers/powercap/arm_scmi_powercap.c seems to be a good reference.

- Mani

> Thanks
> > 
> > - Mani
> > 
> > > This series is based on previous work by Bhupesh Sharma which can be
> > > found at [1]. I'm sending this as a fresh series as it has been a
> > > year since the original version and I have rewritten most of the driver.
> > > 
> > > [1]: https://lore.kernel.org/linux-arm-msm/20220912085049.3517140-1-bhupesh.sharma@linaro.org/
> > > 
> > > ---
> > > Caleb Connolly (4):
> > >        remoteproc: qcom: probe all child devices
> > >        dt-bindings: thermal: Add qcom,qmi-cooling yaml bindings
> > >        thermal: qcom: add qmi-cooling driver
> > >        MAINTAINERS: Add entry for Qualcomm Cooling Driver
> > > 
> > >   .../bindings/remoteproc/qcom,msm8996-mss-pil.yaml  |  13 +
> > >   .../bindings/remoteproc/qcom,pas-common.yaml       |   6 +
> > >   .../bindings/thermal/qcom,qmi-cooling.yaml         | 168 +++++++
> > >   MAINTAINERS                                        |   8 +
> > >   drivers/remoteproc/qcom_q6v5.c                     |   4 +
> > >   drivers/remoteproc/qcom_q6v5_mss.c                 |   8 -
> > >   drivers/thermal/qcom/Kconfig                       |  13 +
> > >   drivers/thermal/qcom/Makefile                      |   1 +
> > >   drivers/thermal/qcom/qmi-cooling.c                 | 520 +++++++++++++++++++++
> > >   drivers/thermal/qcom/qmi-cooling.h                 | 428 +++++++++++++++++
> > >   10 files changed, 1161 insertions(+), 8 deletions(-)
> > > ---
> > > base-commit: 9067f80db58bbce81d5f0703aa2fd261e88bc812
> > > 
> > > // Caleb (they/them)
> > > 
> > 
> 
> -- 
> // Caleb (they/them)

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