linux-kernel - Re: [Patch v7] ACPI: processor: reduce CPUFREQ thermal reduction pctg for Tegra241

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Date:   Wed, 6 Dec 2023 15:43:40 +0530
From:   Sumit Gupta <sumitg@...dia.com>
To:     <rafael@...nel.org>
CC:     <rui.zhang@...el.com>, <lenb@...nel.org>, <lpieralisi@...nel.org>,
        "Sudeep Holla" <sudeep.holla@....com>,
        <linux-acpi@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <treding@...dia.com>,
        <jonathanh@...dia.com>, <bbasu@...dia.com>, <sanjayc@...dia.com>,
        <ksitaraman@...dia.com>, <srikars@...dia.com>,
        <jbrasen@...dia.com>, "Hanjun Guo" <guohanjun@...wei.com>,
        Sumit Gupta <sumitg@...dia.com>
Subject: Re: [Patch v7] ACPI: processor: reduce CPUFREQ thermal reduction pctg
 for Tegra241


>>> From: Srikar Srimath Tirumala <srikars@...dia.com>
>>>
>>> Current implementation of processor_thermal performs software throttling
>>> in fixed steps of "20%" which can be too coarse for some platforms.
>>> We observed some performance gain after reducing the throttle 
>>> percentage.
>>> Change the CPUFREQ thermal reduction percentage and maximum thermal 
>>> steps
>>> to be configurable. Also, update the default values of both for Nvidia
>>> Tegra241 (Grace) SoC. The thermal reduction percentage is reduced to 
>>> "5%"
>>> and accordingly the maximum number of thermal steps are increased as 
>>> they
>>> are derived from the reduction percentage.
>>>
>>> Signed-off-by: Srikar Srimath Tirumala <srikars@...dia.com>
>>> Co-developed-by: Sumit Gupta <sumitg@...dia.com>
>>> Signed-off-by: Sumit Gupta <sumitg@...dia.com>
>>> ---
>>>
>>> Sending this patch separately as the other patch in the series is
>>> applied by Rafael in v6[1]. Revision history before this version is
>>> in the cover letter of v6[1].
>>>
>>> Please review and provide ACK if looks fine.
>>>
>>
>> For arm64 specific changes(a minor nit below though),
>>
>> Acked-by: Sudeep Holla <sudeep.holla@....com>
>>
>>
>> [...]
>>
>>> diff --git a/drivers/acpi/arm64/thermal_cpufreq.c 
>>> b/drivers/acpi/arm64/thermal_cpufreq.c
>>> new file mode 100644
>>> index 000000000000..d524f2cd6044
>>> --- /dev/null
>>> +++ b/drivers/acpi/arm64/thermal_cpufreq.c
>>> @@ -0,0 +1,20 @@
>>> +// SPDX-License-Identifier: GPL-2.0-only
>>> +#include <linux/acpi.h>
>>> +
>>> +#include "../internal.h"
>>> +
>>> +#define SMCCC_SOC_ID_T241      0x036b0241
>>> +
>>
>> [nit] We really need to find better place to define this globally and not
>> locally at each usage site like this. We already have it in GICv3 driver.
>> But that can come as a cleanup later if it causes issue for merging this
>> change.
> 
> Agreed.
> 
> Looks good to me as well.
> 
> Acked-by: Hanjun Guo <guohanjun@...wei.com>
> 

Hi Rafael,

If the change seems fine, could you please apply this patch?

Thanks,
Sumit