Re: [PATCH v2] thermal/of: support thermal zones w/o trips subnode

[Dragan Simic <dsimic@manjaro.org>]

Hello Chen-Yu,

Thanks for the patch.  Please see one comment below.

On 2024-08-09 09:08, Chen-Yu Tsai wrote:
> From: Icenowy Zheng <uwu@icenowy.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@icenowy.me>
> Reviewed-by: Mark Brown <broonie@kernel.org>
> Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
> ---
> Resurrecting this patch specifically for MediaTek MT8183 Kukui devices.
> 
> 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 | 19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/thermal/thermal_of.c 
> b/drivers/thermal/thermal_of.c
> index aa34b6e82e26..f237e74c92fc 100644
> --- a/drivers/thermal/thermal_of.c
> +++ b/drivers/thermal/thermal_of.c
> @@ -128,16 +128,17 @@ static struct thermal_trip
> *thermal_of_trips_init(struct device_node *np, int *n
>  	struct device_node *trips, *trip;
>  	int ret, count;
> 
> +	*ntrips = 0;
>  	trips = 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);
>  	}
> 
>  	count = of_get_child_count(trips);
>  	if (!count) {
> -		pr_err("No trip point defined\n");
> -		ret = -EINVAL;
> +		pr_debug("No trip point defined\n");
> +		ret = -ENXIO;
>  		goto out_of_node_put;
>  	}
> 
> @@ -162,7 +163,6 @@ static struct thermal_trip
> *thermal_of_trips_init(struct device_node *np, int *n
> 
>  out_kfree:
>  	kfree(tt);
> -	*ntrips = 0;
>  out_of_node_put:
>  	of_node_put(trips);

It might be a bit cleaner to keep the "*ntrips = 0" assignment
in the error handling path(s) only, with the positions of the goto
labels adjusted a bit, and then assign -ENXIO to "ret" and jump
to the right label when of_get_child_by_name(np, "trips") fails,
instead of returning from there.

If it's unclear what I'm talking about, please let me know and
I'll send back the proposed hunk.

> @@ -490,8 +490,13 @@ 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);
> -		return ERR_CAST(trips);
> +		if (PTR_ERR(trips) != -ENXIO) {
> +			pr_err("Failed to find trip points for %pOFn id=%d\n", sensor, id);
> +			return ERR_CAST(trips);
> +		}
> +
> +		pr_warn("Failed to find trip points for %pOFn id=%d\n", sensor, id);
> +		trips = NULL;
>  	}
> 
>  	ret = thermal_of_monitor_init(np, &delay, &pdelay);