Re: [PATCH v11 1/5] dt-bindings: Introduce QCOM Sleep stats bindings

[Maulik Shah]

Hi Stephan,

On 10/8/2021 1:20 AM, Stephan Gerhold wrote:
> On Thu, Oct 07, 2021 at 03:27:25PM +0530, Maulik Shah wrote:
> > From: Mahesh Sivasubramanian <msivasub@xxxxxxxxxxxxxx>
> >
> > Add device binding documentation for Qualcomm Technologies, Inc. (QTI)
> > Sleep stats driver. The driver is used for displaying Sleep statistic maintained
> > by Always On Processor or Resource Power Manager.
> >
> > Cc: devicetree@xxxxxxxxxxxxxxx
> > Signed-off-by: Mahesh Sivasubramanian <msivasub@xxxxxxxxxxxxxx>
> > Signed-off-by: Lina Iyer <ilina@xxxxxxxxxxxxxx>
> > Signed-off-by: Maulik Shah <mkshah@xxxxxxxxxxxxxx>
> > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> > Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> > Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
> > ---
> >   .../bindings/soc/qcom/qcom-sleep-stats.yaml        | 47 ++++++++++++++++++++++
> >   1 file changed, 47 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/soc/qcom/qcom-sleep-stats.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom-sleep-stats.yaml b/Documentation/devicetree/bindings/soc/qcom/qcom-sleep-stats.yaml
> > new file mode 100644
> > index 0000000..5213daf
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/soc/qcom/qcom-sleep-stats.yaml
> > @@ -0,0 +1,47 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/soc/qcom/qcom-sleep-stats.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Qualcomm Technologies, Inc. (QTI) Sleep stats bindings
> > +
> > +maintainers:
> > +  - Maulik Shah <mkshah@xxxxxxxxxxxxxx>
> > +
> > +description:
> > +  Always On Processor/Resource Power Manager maintains statistics of the SoC
> > +  sleep modes involving powering down of the rails and oscillator clock.
> > +
> > +  Statistics includes SoC sleep mode type, number of times low power mode were
> > +  entered, time of last entry, time of last exit and accumulated sleep duration.
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - qcom,rpmh-sleep-stats
> > +      - qcom,rpm-sleep-stats
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  # Example of rpmh sleep stats
> > +  - |
> > +    sram@c3f0000 {
> > +      compatible = "qcom,rpmh-sleep-stats";
> > +      reg = <0x0c3f0000 0x400>;
> > +    };
> > +  # Example of rpm sleep stats
> > +  - |
> > +    sram@4690000 {
> > +      compatible = "qcom,rpm-sleep-stats";
> > +      reg = <0x04690000 0x400>;
> > +    };
>
> Does this region really only contain "rpm-*sleep*-stats"? AFAICT this is
> really a more generic memory region where various offsets are read from.

Right the area contains all kind of sleep stats/logs.

> These are all the offsets in msm8998-pm.dtsi downstream [1]:
>    ...9000c: rpm-rail-stats offset
>    ...90014: rpm-sleep-stats offset (RPM_DYNAMIC_ADDR in your driver)
>    ...90018: rpm-log offset
>    ...9001c: "RPM FREE HEAP SPACE"
>
> How would you set up any of the other drivers if the entire region
> is declared as "rpm-sleep-stats"?

We don't need to setup other drivers.
The idea is to have single stats driver (qcom_sleep_stats) that can be 
enahanced to to read other stats also on both RPM/ PRMH targets.

Today this driver reads only sleep stats from offset 0x90014.
if in future say, we want to read rpm-rail-stats from offset 0x9000c 
then it can be added in the existing driver.

In the rpm data, add one more entry to indicate reading rpm-rail-stats,
something like below and add new compatible flag for the target, may be
"qcom,rpm-sleep-stats-legacy" and should work like,

#define RPM_RAIL_STATS_ADDR 0xc

static const struct stats_config rpm_data = {
        .stats_offset = 0,
        .num_records = 2,
        .appended_stats_avail = true,
        .dynamic_offset = true,
        .rpm_rail_stats = true,
};

and check in driver probe like

        if (config->rpm_rail_stats) {
	//create rpm rail stats related files.
        }

Similarly for other rpm-logs / any other stats can be added in same driver.

Hope this clarifies.

> Perhaps this region should have a more generic name that represents what
> it actually is and not only one of the information it contains, similar
> to "qcom,rpm-msg-ram"?

sram looks good to me. Actually on RPM targets its RPM data ram and RPMH 
targets its msgram. To keep the name common sram is used here.

Thanks,
Maulik

> Thanks,
> Stephan
>
> [1]: https://source.codeaurora.org/quic/la/kernel/msm-4.4/tree/arch/arm/boot/dts/qcom/msm8998-pm.dtsi?h=LA.UM.8.4.1.c25#n271

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