netdev - Re: [PATCH v2 8/9] thermal: of: Set THERMAL_TRIP_FLAG_RW

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Date: Thu, 22 Feb 2024 14:59:53 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>, Linux PM <linux-pm@...r.kernel.org>, 
	Lukasz Luba <lukasz.luba@....com>, LKML <linux-kernel@...r.kernel.org>, 
	Stanislaw Gruszka <stanislaw.gruszka@...ux.intel.com>, 
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>, Zhang Rui <rui.zhang@...el.com>, 
	netdev@...r.kernel.org, Ido Schimmel <idosch@...dia.com>, Petr Machata <petrm@...dia.com>, 
	Miri Korenblit <miriam.rachel.korenblit@...el.com>, linux-wireless@...r.kernel.org, 
	Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, 
	Pengutronix Kernel Team <kernel@...gutronix.de>, 
	Manaf Meethalavalappu Pallikunhi <quic_manafm@...cinc.com>
Subject: Re: [PATCH v2 8/9] thermal: of: Set THERMAL_TRIP_FLAG_RW_TEMP directly

On Thu, Feb 22, 2024 at 2:48 PM Daniel Lezcano
<daniel.lezcano@...aro.org> wrote:
>
> On 12/02/2024 19:40, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >
> > It is now possible to flag trip points with THERMAL_TRIP_FLAG_RW_TEMP
> > to allow their temperature to be set from user space via sysfs instead
> > of using a nonzero writable trips mask during thermal zone registration,
> > so make the OF thermal code do that.
> >
> > No intentional functional impact.
> >
> > Note that this change is requisite for dropping the mask argument from
> > thermal_zone_device_register_with_trips() going forward.
> >
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > ---
> >
> > v1 -> v2: Rename trip flag (Stanislaw).
> >
> > ---
> >   drivers/thermal/thermal_of.c |    8 ++++----
> >   1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > Index: linux-pm/drivers/thermal/thermal_of.c
> > ===================================================================
> > --- linux-pm.orig/drivers/thermal/thermal_of.c
> > +++ linux-pm/drivers/thermal/thermal_of.c
> > @@ -117,6 +117,8 @@ static int thermal_of_populate_trip(stru
> >               return ret;
> >       }
> >
> > +     trip->flags = THERMAL_TRIP_FLAG_RW_TEMP;
> > +
> >       return 0;
> >   }
>
> Even if you are not at the origin of this default behavior. I'm
> wondering if we should be more protective against changes from userspace
> when the firmware is telling us to protect the silicon at a specific
> temperature.
>
> What do you think if we set the THERMAL_TRIP_FLAG_RW_TEMP only if the
> trip point is not bound to a cooling device?
>
> So trip points without associated cooling device can be writable but
> others can be considered as managed by the kernel and no modifiable.

This sounds reasonable to me.

This is mostly relevant to thermal_of anyway, because the other
drivers asking for writable trip temperature seem to want it
regardless.

> (This comment does not put in question this patch BTW)

OK