linux-kernel - Re: [PATCH v3] thermal/of: support thermal zones w/o trips subnode

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Message-ID: <CAGXv+5GToNr=6D_j3A-HzmCQJNx-fm+A=KgxhqhtSES1CRMvJQ@mail.gmail.com>
Date: Fri, 18 Oct 2024 15:12:26 +0800
From: Chen-Yu Tsai <wenst@...omium.org>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Daniel Lezcano <daniel.lezcano@...aro.org>, Amit Kucheria <amitk@...nel.org>, 
	Zhang Rui <rui.zhang@...el.com>, Icenowy Zheng <uwu@...nowy.me>, Mark Brown <broonie@...nel.org>, 
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev, 
	Nícolas F. R. A. Prado <nfraprado@...labora.com>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
	Matthias Brugger <matthias.bgg@...il.com>, linux-mediatek@...ts.infradead.org, 
	Hsin-Te Yuan <yuanhsinte@...omium.org>
Subject: Re: [PATCH v3] thermal/of: support thermal zones w/o trips subnode

On Thu, Oct 17, 2024 at 6:57 PM Rafael J. Wysocki <rafael@...nel.org> wrote:
>
> On Thu, Oct 17, 2024 at 11:05 AM Chen-Yu Tsai <wenst@...omium.org> wrote:
> >
> > From: Icenowy Zheng <uwu@...nowy.me>
> >
> > Although the current device tree binding of thermal zones require the
> > trips subnode, the binding in kernel v5.15 does not require it, and many
> > device trees shipped with the kernel, for example,
> > allwinner/sun50i-a64.dtsi and mediatek/mt8183-kukui.dtsi in ARM64, still
> > comply to the old binding and contain no trips subnode.
> >
> > Allow the code to successfully register thermal zones w/o trips subnode
> > for DT binding compatibility now.
> >
> > Furtherly, the inconsistency between DTs and bindings should be resolved
> > by either adding empty trips subnode or dropping the trips subnode
> > requirement.
> >
> > Fixes: d0c75fa2c17f ("thermal/of: Initialize trip points separately")
> > Signed-off-by: Icenowy Zheng <uwu@...nowy.me>
> > Reviewed-by: Mark Brown <broonie@...nel.org>
> > Signed-off-by: Chen-Yu Tsai <wenst@...omium.org>
> > ---
> > Changes since v2:
> > - Stacked on top of Krzysztof's cleanup patches
> >   - thermal: of: Use scoped memory and OF handling to simplify thermal_of_trips_init() [1]
> > - Adjusted to account for eliminated error path
> >
> > [1] https://lore.kernel.org/all/20241010-b4-cleanup-h-of-node-put-thermal-v4-2-bfbe29ad81f4@linaro.org/
> >
> > Changes since v1:
> > - set *ntrips at beginning of thermal_of_trips_init()
> > - Keep goto out_of_node_put in of_get_child_count(trips) == 0 branch
> > - Check return value of thermal_of_trips_init(), if it is -ENXIO, print
> >   warning and clear |trips| pointer
> > - Drop |mask| change, as the variable was removed
> >
> > I kept Mark's reviewed-by since the changes are more stylish than
> > functional.
> > ---
> >  drivers/thermal/thermal_of.c | 20 +++++++++++++-------
> >  1 file changed, 13 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/thermal/thermal_of.c b/drivers/thermal/thermal_of.c
> > index 93f7c6f8d06d..be1fa6478c21 100644
> > --- a/drivers/thermal/thermal_of.c
> > +++ b/drivers/thermal/thermal_of.c
> > @@ -99,14 +99,14 @@ static struct thermal_trip *thermal_of_trips_init(struct device_node *np, int *n
> >
> >         struct device_node *trips __free(device_node) = of_get_child_by_name(np, "trips");
> >         if (!trips) {
> > -               pr_err("Failed to find 'trips' node\n");
> > -               return ERR_PTR(-EINVAL);
> > +               pr_debug("Failed to find 'trips' node\n");
> > +               return ERR_PTR(-ENXIO);
>
> Why not
>
> *ntrips = 0;
> return NULL;

That indeed seems cleaner.

> >         }
> >
> >         count = of_get_child_count(trips);
> >         if (!count) {
> > -               pr_err("No trip point defined\n");
> > -               return ERR_PTR(-EINVAL);
> > +               pr_debug("No trip point defined\n");
> > +               return ERR_PTR(-ENXIO);
>
> Is this based on the current mainline code?

This is based on Krzysztof's scoped memory patch:

  thermal: of: Use scoped memory and OF handling to simplify
thermal_of_trips_init()
  https://lore.kernel.org/all/20241010-b4-cleanup-h-of-node-put-thermal-v4-2-bfbe29ad81f4@linaro.org/

I should have made it more obvious in the footer.

> >         }
> >
> >         struct thermal_trip *tt __free(kfree) = kzalloc(sizeof(*tt) * count, GFP_KERNEL);
> > @@ -386,9 +386,15 @@ static struct thermal_zone_device *thermal_of_zone_register(struct device_node *
> >
> >         trips = thermal_of_trips_init(np, &ntrips);
> >         if (IS_ERR(trips)) {
> > -               pr_err("Failed to find trip points for %pOFn id=%d\n", sensor, id);
> > -               ret = PTR_ERR(trips);
> > -               goto out_of_node_put;
> > +               if (PTR_ERR(trips) != -ENXIO) {
> > +                       pr_err("Failed to find trip points for %pOFn id=%d\n", sensor, id);
> > +                       ret = PTR_ERR(trips);
> > +                       goto out_of_node_put;
> > +               }
> > +
> > +               pr_warn("Failed to find trip points for %pOFn id=%d\n", sensor, id);
>
> Wouldn't pr_info() be sufficient for this?

Works for me. I should also reword this and the existing error message
to be less confusing.


Thanks
ChenYu


> > +               trips = NULL;
> > +               ntrips = 0;
> >         }
> >
> >         ret = thermal_of_monitor_init(np, &delay, &pdelay);
> > --