linux-kernel - Re: [PATCH 4/4] leds: netdev trigger: allow setting initial values in device tree

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Message-ID: <98fda0ee-555d-86a5-a4f1-1774271e4b6d@gmail.com>
Date:   Thu, 14 Mar 2019 11:32:17 +0100
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        Pavel Machek <pavel@....cz>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, linux-leds@...r.kernel.org,
        devicetree@...r.kernel.org, linux-can@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH 4/4] leds: netdev trigger: allow setting initial values in
 device tree

Hi Rasmus,

Thank you for the patch set.

I have one comment below.

On 3/13/19 9:26 PM, Rasmus Villemoes wrote:
> It can be quite convenient to initialize a netdev-triggered LED with a
> device name and setting the rx,tx,link properties from device tree,
> instead of having to do that in an init script in userspace.
> 
> My main motivation for this is to be able to switch away from the
> deprecated CONFIG_CAN_LEDS, so add an example based on that and add a
> pointer in the net/can/Kconfig file.
> 
> Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
> ---
>   .../devicetree/bindings/leds/common.txt       | 17 ++++++++++
>   drivers/leds/trigger/ledtrig-netdev.c         | 31 +++++++++++++++++++
>   drivers/net/can/Kconfig                       |  3 +-
>   3 files changed, 50 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/leds/common.txt b/Documentation/devicetree/bindings/leds/common.txt
> index 7cb88460a47c..4f3a97e73417 100644
> --- a/Documentation/devicetree/bindings/leds/common.txt
> +++ b/Documentation/devicetree/bindings/leds/common.txt
> @@ -43,6 +43,23 @@ Optional properties for child nodes:
>                   Documentation/ABI/testing/sysfs-class-led-trigger-netdev)
>                   to reflect the state and activity of a net device.
>   
> +                The optional child node netdev can be used to
> +                configure initial values for the link, rx, tx and
> +                device_name properties. For example, setting
> +                linux,default-trigger = "netdev" and adding the child
> +                node
> +
> +                netdev {
> +                    rx;
> +                    tx;
> +                    link;
> +                    device-name = "can0";
> +                };
> +
> +                can be used to replace 'linux,default-trigger =
> +                "can0-rxtx"' that relies on the deprecated
> +                CONFIG_CAN_LEDS.
> +
>   - led-pattern : Array of integers with default pattern for certain triggers.
>                   Each trigger may parse this property differently:
>                   - one-shot : two numbers specifying delay on and delay off (in ms),
> diff --git a/drivers/leds/trigger/ledtrig-netdev.c b/drivers/leds/trigger/ledtrig-netdev.c
> index 55153a7e8433..1f7c86df1e91 100644
> --- a/drivers/leds/trigger/ledtrig-netdev.c
> +++ b/drivers/leds/trigger/ledtrig-netdev.c
> @@ -20,6 +20,7 @@
>   #include <linux/list.h>
>   #include <linux/module.h>
>   #include <linux/netdevice.h>
> +#include <linux/of.h>
>   #include <linux/spinlock.h>
>   #include <linux/timer.h>
>   #include "../leds.h"
> @@ -395,6 +396,35 @@ static void netdev_trig_work(struct work_struct *work)
>   			(atomic_read(&trigger_data->interval)*2));
>   }
>   
> +static void netdev_trig_of_init(struct led_classdev *led_cdev,
> +				struct led_netdev_data *trigger_data)
> +{
> +	struct device_node *np = led_cdev->dev->of_node;
> +	const char *device_name;
> +
> +	if (!np)
> +		return;
> +	np = of_get_child_by_name(np, "netdev");
> +	if (!np)
> +		return;
> +
> +	if (of_property_read_bool(np, "link"))
> +		__set_bit(NETDEV_LED_LINK, &trigger_data->mode);
> +	if (of_property_read_bool(np, "tx"))
> +		__set_bit(NETDEV_LED_TX, &trigger_data->mode);
> +	if (of_property_read_bool(np, "rx"))
> +		__set_bit(NETDEV_LED_RX, &trigger_data->mode);
> +	if (!of_property_read_string(np, "device-name", &device_name)) {
> +		unsigned len = strlen(device_name);
> +
> +		if (len < IFNAMSIZ)
> +			set_device(trigger_data, device_name, len);
> +	}
> +	set_baseline_state(trigger_data);
> +
> +	of_node_put(np);
> +}
> +
>   static int netdev_trig_activate(struct led_classdev *led_cdev)
>   {
>   	struct led_netdev_data *trigger_data;
> @@ -418,6 +448,7 @@ static int netdev_trig_activate(struct led_classdev *led_cdev)
>   	trigger_data->mode = 0;
>   	atomic_set(&trigger_data->interval, msecs_to_jiffies(50));
>   	trigger_data->last_activity = 0;
> +	netdev_trig_of_init(led_cdev, trigger_data);

You want to execute this only if recently introduced flag
LED_INIT_DEFAULT_TRIGGER is set. Please compare how
drivers/leds/trigger/ledtrig-pattern.c uses it.

>   
>   	led_set_trigger_data(led_cdev, trigger_data);
>   
> diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
> index e0f0ad7a550a..91703a96b636 100644
> --- a/drivers/net/can/Kconfig
> +++ b/drivers/net/can/Kconfig
> @@ -77,7 +77,8 @@ config CAN_LEDS
>   	# everything that this driver is doing. This is marked as broken
>   	# because it uses stuff that is intended to be changed or removed.
>   	# Please consider switching to the netdev trigger and confirm it
> -	# fulfills your needs instead of fixing this driver.
> +	# fulfills your needs instead of fixing this driver. See e.g.
> +	# Documentation/devicetree/bindings/leds/common.txt
>   	depends on BROKEN
>   	select LEDS_TRIGGERS
>   	---help---
> 

-- 
Best regards,
Jacek Anaszewski