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

[Manivannan Sadhasivam <mani@kernel.org>]

On Mon, Oct 02, 2023 at 07:00:27PM +0300, Dmitry Baryshkov wrote:
> On Mon, 2 Oct 2023 at 18:58, Manivannan Sadhasivam <mani@kernel.org> wrote:
> >
> > On Mon, Oct 02, 2023 at 06:00:37PM +0300, Dmitry Baryshkov wrote:
> > > On Mon, 2 Oct 2023 at 17:52, Manivannan Sadhasivam <mani@kernel.org> wrote:
> > > >
> > > > 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.
> > >
> > > As far as I understand, no. It is perfectly fine to have 'cooling'
> > > devices, which react to external thermal monitoring events. I might be
> > > mistaken, but I think that is the case here, isn't it?
> > >
> >
> > Yes it is represented as cooling device(s). But I do not see any cognizant way
> > to plug it with thermal zones i.e., unless TMD itself reports temperature of the
> > modem, using it as a cooling device for external temperature events doesn't
> > sound good to me.
> 
> Why? We have compute, q6, wlan tsens sensors. So it seems natural to
> tell CDSP to slow down if compute sensor reports overheating.
> 

TMD is for external devices such as PCIe modems as well. Is there a temperature
sensor for that?

- Mani

> >
> > - Mani
> >
> > > >
> > > > > >
> > > > > > 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)
> > > >
> > > > --
> > > > மணிவண்ணன் சதாசிவம்
> > >
> > >
> > >
> > > --
> > > With best wishes
> > > Dmitry
> >
> > --
> > மணிவண்ணன் சதாசிவம்
> 
> 
> 
> -- 
> With best wishes
> Dmitry

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