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Date:   Tue, 18 Apr 2023 15:44:44 +0200
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Subject: Re: [PATCH v3 5/6] thermal/drivers/acpi: Make cross dev link optional
 by configuration
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To:     "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     rui.zhang@intel.com, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org, Len Brown <lenb@kernel.org>,
        "open list:ACPI" <linux-acpi@vger.kernel.org>
References: <20230413114647.3878792-1-daniel.lezcano@linaro.org>
 <20230413114647.3878792-6-daniel.lezcano@linaro.org>
 <CAJZ5v0jqB18c1u-eqcEiXW+fOH=nX=Uu3xi5sp2F9udsFUrYew@mail.gmail.com>
From:   Daniel Lezcano <daniel.lezcano@linaro.org>
In-Reply-To: <CAJZ5v0jqB18c1u-eqcEiXW+fOH=nX=Uu3xi5sp2F9udsFUrYew@mail.gmail.com>
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On 18/04/2023 15:38, Rafael J. Wysocki wrote:
> On Thu, Apr 13, 2023 at 1:47 PM Daniel Lezcano
> <daniel.lezcano@linaro.org> wrote:
>>
>> The ACPI thermal driver creates a link in the thermal zone device
>> sysfs directory pointing to the device sysfs directory. At the same
>> time, it creates a back pointer link from the device to the thermal
>> zone device sysfs directory.
>>
>>  From a generic perspective, having a device pointer in the sysfs
>> thermal zone directory may make sense. But the opposite is not true as
>> the same driver can be related to multiple thermal zones.
>>
>> The usage of these information is very specific to ACPI and it is
>> questionable if they are really needed.
>>
>> Let's make the code optional and disable it by default. If it hurts,
>> we will revert this change.
>>
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>> ---
>>   drivers/acpi/Kconfig   | 13 +++++++++
>>   drivers/acpi/thermal.c | 62 ++++++++++++++++++++++++++++--------------
>>   2 files changed, 55 insertions(+), 20 deletions(-)
>>
>> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
>> index ccbeab9500ec..7df4e18f06ef 100644
>> --- a/drivers/acpi/Kconfig
>> +++ b/drivers/acpi/Kconfig
>> @@ -336,6 +336,19 @@ config ACPI_THERMAL
>>            To compile this driver as a module, choose M here:
>>            the module will be called thermal.
>>
>> +config ACPI_THERMAL_SYSFS_ADDON
>> +       bool "Enable thermal sysfs addon"
>> +       depends on ACPI_THERMAL
>> +       def_bool n
>> +       help
>> +        Enable sysfs extra information added in the thermal zone and
>> +        the driver specific sysfs directories. That could be a link
>> +        to the associated thermal zone as well as a link pointing to
>> +        the device from the thermal zone. By default those are
>> +        disabled and are candidate for removal, if you need these
>> +        information anyway, enable the option or upgrade the
>> +        userspace program using them.
>> +
> 
> I don't think that the Kconfig option is appropriate and the help text
> above isn't really helpful.

I'm sorry, I'm missing something. Don't we want to make these sysfs 
extra information optional and disable them by default ?

>>   config ACPI_PLATFORM_PROFILE
>>          tristate
>>
>> diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
>> index 5763db4528b8..30fe189d04f8 100644
>> --- a/drivers/acpi/thermal.c
>> +++ b/drivers/acpi/thermal.c
>> @@ -787,9 +787,44 @@ static struct thermal_zone_device_ops acpi_thermal_zone_ops = {
>>          .critical = acpi_thermal_zone_device_critical,
>>   };
>>
>> +#ifdef CONFIG_ACPI_THERMAL_SYSFS_ADDON
> 
> I agree with moving the code in question to separate functions, but I
> don't agree with putting it under the Kconfig option.

Do you mean use IS_ENABLED check like what is done with Menlow patch 6 ?

[ ... ]


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