linux-kernel - Re: [PATCH v3 5/6] thermal/drivers/acpi: Make cross dev link optional by configuration

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Message-ID: <CAJZ5v0hkF37RL4fxqE7+iUw7gEtb+KMyDKBpjdO=DE72OSHFtg@mail.gmail.com>
Date:   Tue, 18 Apr 2023 15:47:44 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>, rui.zhang@...el.com,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        Len Brown <lenb@...nel.org>,
        "open list:ACPI" <linux-acpi@...r.kernel.org>
Subject: Re: [PATCH v3 5/6] thermal/drivers/acpi: Make cross dev link optional
 by configuration

On Tue, Apr 18, 2023 at 3:44 PM Daniel Lezcano
<daniel.lezcano@...aro.org> wrote:
>
> On 18/04/2023 15:38, Rafael J. Wysocki wrote:
> > On Thu, Apr 13, 2023 at 1:47 PM Daniel Lezcano
> > <daniel.lezcano@...aro.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@...aro.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 ?

No, I mean no Kconfig option at all for this one at least for now.