Hi Denis,
There is already a property for that purpose: default-state = "keep";
Please just use it instead.
Best regards,
Jacek Anaszewski
On 3/9/20 9:24 AM, Denis Osterland-Heim wrote:
> This patch add "pwm,uninitalized" devicetree flag support to pwm
> leds, which allows to defer pwm init to first use of led.
>
> This allows to configure the PWM early in bootloader to let the LED
> blink until an application in Linux userspace set something different.
>
> Signed-off-by: Denis Osterland-Heim <Denis.Osterland@xxxxxxxxx>
> ---
> Hi,
>
> I want to ask if such a patch is intresting for mainline and
> if it is woth to think about how to represent this state to user space.
>
> Regards Denis
>
> Documentation/devicetree/bindings/leds/leds-pwm.txt | 1 +
> drivers/leds/leds-pwm.c | 10 ++++++++--
> include/linux/leds_pwm.h | 1 +
> 3 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/leds/leds-pwm.txt b/Documentation/devicetree/bindings/leds/leds-pwm.txt
> index 6c6583c35f2f..4f58df631fc9 100644
> --- a/Documentation/devicetree/bindings/leds/leds-pwm.txt
> +++ b/Documentation/devicetree/bindings/leds/leds-pwm.txt
> @@ -19,6 +19,7 @@ LED sub-node properties:
> see Documentation/devicetree/bindings/leds/common.txt
> - linux,default-trigger : (optional)
> see Documentation/devicetree/bindings/leds/common.txt
> +- pwm,uninitalized : defer PWM init to first brightness change of led
>
> Example:
>
> diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
> index 8b6965a563e9..02c90f05602a 100644
> --- a/drivers/leds/leds-pwm.c
> +++ b/drivers/leds/leds-pwm.c
> @@ -97,7 +97,8 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
> * FIXME: pwm_apply_args() should be removed when switching to the
> * atomic PWM API.
> */
> - pwm_apply_args(led_data->pwm);
> + if (!led->pwm_uninitialized)
> + pwm_apply_args(led_data->pwm);
>
> pwm_get_args(led_data->pwm, &pargs);
>
> @@ -108,7 +109,9 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
> ret = devm_led_classdev_register(dev, &led_data->cdev);
> if (ret == 0) {
> priv->num_leds++;
> - led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
> + if (!led->pwm_uninitialized)
> + led_pwm_set(&led_data->cdev,
> + led_data->cdev.brightness);
> } else {
> dev_err(dev, "failed to register PWM led for %s: %d\n",
> led->name, ret);
> @@ -143,6 +146,9 @@ static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
> fwnode_property_read_u32(fwnode, "max-brightness",
> &led.max_brightness);
>
> + led.pwm_uninitialized = fwnode_property_read_bool(fwnode,
> + "pwm,uninitialized");
> +
> ret = led_pwm_add(dev, priv, &led, fwnode);
> if (ret) {
> fwnode_handle_put(fwnode);
> diff --git a/include/linux/leds_pwm.h b/include/linux/leds_pwm.h
> index 93d101d28943..0b04dfd43654 100644
> --- a/include/linux/leds_pwm.h
> +++ b/include/linux/leds_pwm.h
> @@ -10,6 +10,7 @@ struct led_pwm {
> const char *default_trigger;
> unsigned pwm_id __deprecated;
> u8 active_low;
> + u8 pwm_uninitialized;
> unsigned max_brightness;
> unsigned pwm_period_ns;
> };
>
