linux-kernel - Re: [PATCH v5 6/6] qcom/soc/drivers: Add DTPM description for sdm845

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Message-ID: <56905f98-d8a1-0631-8f1e-ccd403c6add2@linaro.org>
Date:   Sun, 19 Dec 2021 21:27:31 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Steev Klimaszewski <steev@...i.org>, rjw@...ysocki.net
Cc:     lukasz.luba@....com, robh@...nel.org, heiko@...ech.de,
        arnd@...aro.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, ulf.hansson@...aro.org,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH v5 6/6] qcom/soc/drivers: Add DTPM description for sdm845

On 19/12/2021 19:44, Steev Klimaszewski wrote:
> Hi Daniel,
> 
> On 12/18/21 2:11 PM, Daniel Lezcano wrote:
>> Hi Steev,
>>
>> thanks for taking the time to test the series.
> 
> My C630 is my daily driver and main computer, so I don't mind testing
> things to improve its usage at all.
> 
> 
>> <snip>
>> Yes, the module is designed to be loaded only. I did not wanted to add
>> more complexity in the driver as unloading it is not the priority ATM.
>> We need this to be a module in order to load it after the other devices.
> Makes sense, I just wasn't entirely sure if it was on purpose or not.
>>>> +    depends on DTPM
>>>> +    help
>>>> +     Describe the hierarchy for the Dynamic Thermal Power
>>>> +     Management tree on this platform. That will create all the
>>>> +     power capping capable devices.
>>>> +
>>>>    endmenu
>>>> diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
>>>> index 70d5de69fd7b..cf38496c3f61 100644
>>>> --- a/drivers/soc/qcom/Makefile
>>>> +++ b/drivers/soc/qcom/Makefile
>>>> @@ -28,3 +28,4 @@ obj-$(CONFIG_QCOM_LLCC) += llcc-qcom.o
>>>>    obj-$(CONFIG_QCOM_RPMHPD) += rpmhpd.o
>>>>    obj-$(CONFIG_QCOM_RPMPD) += rpmpd.o
>>>>    obj-$(CONFIG_QCOM_KRYO_L2_ACCESSORS) +=    kryo-l2-accessors.o
>>>> +obj-$(CONFIG_QCOM_DTPM) += dtpm.o
>> [ ... ]
> I noticed this as well, and was going to ask if it shouldn't be named
> qcom_dtpm, but I don't think it matters since it would be in
> /lib/modules/$kver/kernel/drivers/soc/qcom ?

Right

>>>> +static struct of_device_id __initdata sdm845_dtpm_match_table[] = {
>>>> +        { .compatible = "qcom,sdm845", .data = sdm845_hierarchy },
>>>> +        {},
>>>> +};
>>>> +
>>>> +static int __init sdm845_dtpm_init(void)
>>>> +{
>>>> +    return dtpm_create_hierarchy(sdm845_dtpm_match_table);
>>>> +}
>>>> +late_initcall(sdm845_dtpm_init);
>>>> +
>>>> +MODULE_DESCRIPTION("Qualcomm DTPM driver");
>>>> +MODULE_LICENSE("GPL");
>>>> +MODULE_ALIAS("platform:dtpm");
>>>> +MODULE_AUTHOR("Daniel Lezcano <daniel.lezcano@...nel.org");
>>>> +
>>> It does seem to work aside from not being able to modprobe -r the
>>> module. Although I do see
>>>
>>> [   35.849622] dtpm: Registered dtpm node 'sdm845' / 0-0 uW,
>>> [   35.849652] dtpm: Registered dtpm node 'package' / 0-0 uW,
>>> [   35.849676] dtpm: Registered dtpm node 'cpu0-cpufreq' /
>>> 40000-436000 uW,
>>> [   35.849702] dtpm: Registered dtpm node 'cpu4-cpufreq' /
>>> 520000-5828000 uW,
>>> [   35.849734] dtpm_devfreq: No energy model available for '5000000.gpu'
>>> [   35.849738] dtpm: Failed to setup '/soc@...pu@...0000': -22
>>>
>>> If the devfreq issue with the gpu isn't expected, are we missing
>>> something for the c630?
>> Yes, the energy model is missing for the GPU, very likely the
>> 'dynamic-power-coefficient' property is missing in the gpu section.
>>
>> A quick test could be to add a value like 800. The resulting power
>> numbers will be wrong but it should be possible to act on the
>> performance by using these wrong power numbers.
>>
>>    -- Daniel
>>
> So, I'm definitely not the greatest of kernel hackers, just enough
> knowledge to be dangerous and I know how to apply patches properly....
> I'm not able to actually get this working.  I've tried adding it with a
> few different numbers, and any time i try to add the d-p-c, I get
> 
> Dec 18 15:00:49 limitless kernel: [   57.394503] adreno 5000000.gpu: EM:
> invalid perf. state: -22
> Dec 18 15:00:49 limitless kernel: [   57.394515] dtpm_devfreq: No energy
> model available for '5000000.gpu'
> Dec 18 15:00:49 limitless kernel: [   57.394519] dtpm: Failed to setup
> '/soc@...pu@...0000': -22

I've been through the code and I suspect something is missing in the
mainline kernel for devfreq vs energy model. Not related to DTPM actually.

I'll double check if that could be added beside this series


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