Subject: Re: [PATCH net-next 4/4] net: dsa: realtek: add LED drivers for rtl8366rb

From: Simon Horman <[email-masked]>
Date: Sun, 10 Mar 2024 11:49:28 +0000

On Sun, Mar 10, 2024 at 01:52:01AM -0300, Luiz Angelo Daros de Luca wrote:
> This commit introduces LED drivers for rtl8366rb, enabling LEDs to be
> described in the device tree using the same format as qca8k. Each port
> can configure up to 4 LEDs.
> 
> If all LEDs in a group use the default state "keep", they will use the
> default behavior after a reset. Changing the brightness of one LED,
> either manually or by a trigger, will disable the default hardware
> trigger and switch the entire LED group to manually controlled LEDs.
> Once in this mode, there is no way to revert to hardware-controlled LEDs
> (except by resetting the switch).
> 
> Software triggers function as expected with manually controlled LEDs.
> 
> Signed-off-by: Luiz Angelo Daros de Luca <[email-masked]>
> Reviewed-by: Linus Walleij <[email-masked]>
> ---
>  drivers/net/dsa/realtek/rtl8366rb.c | 270 ++++++++++++++++++++++++++++++++----

...

> +static int rtl8366rb_setup_led(struct realtek_priv *priv, struct dsa_port *dp,
> +			       struct fwnode_handle *led_fwnode)
> +{
> +	struct rtl8366rb *rb = priv->chip_data;
> +	struct led_init_data init_data = { };
> +	struct rtl8366rb_led *led;
> +	enum led_default_state state;
> +	u32 led_group;
> +	int ret;

nit: Please consider using reverse xmas tree - longest line to shortest -
     for local variables in networking code.

...

> +static int rtl8366rb_setup_leds(struct realtek_priv *priv)
> +{
> +	struct device_node *leds_np, *led_np;
> +	struct dsa_switch *ds = &priv->ds;
> +	struct dsa_port *dp;
> +	int ret;
> +
> +	dsa_switch_for_each_port(dp, ds) {
> +		if (!dp->dn)
> +			continue;
> +
> +		leds_np = of_get_child_by_name(dp->dn, "leds");
> +		if (!leds_np) {
> +			dev_dbg(priv->dev, "No leds defined for port %d",
> +				dp->index);
> +			continue;
> +		}
> +
> +		for_each_child_of_node(leds_np, led_np) {
> +			ret = rtl8366rb_setup_led(priv, dp,
> +						  of_fwnode_handle(led_np));
> +			if (ret) {
> +				of_node_put(led_np);

FWIIW, Coccinelle complans about "probable double put" here.
But it looks correct to me as it's only called when breaking out of
the loop, when it is required AFAIK.

> +				break;
> +			}
> +		}
> +
> +		of_node_put(leds_np);
> +		if (ret)

I'm unsure if this can happen. But if for_each_child_of_node()
iterates zero times then ret may be uninitialised here.

Flagged by Smatch.

> +			return ret;
> +	}
> +	return 0;
> +}

...