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Message-ID: <4ae4d83b-8dee-72e4-3860-dd420a29115e@gmail.com>
Date: Mon, 15 Jul 2019 22:42:52 +0200
From: Jacek Anaszewski <jacek.anaszewski@...il.com>
To: Jean-Jacques Hiblot <jjhiblot@...com>, pavel@....cz,
robh+dt@...nel.org, mark.rutland@....com,
daniel.thompson@...aro.org
Cc: dmurphy@...com, linux-leds@...r.kernel.org,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 2/2] leds: Add control of the voltage/current regulator
to the LED core
Hi Jean,
Thank you for the patch.
I have one issue. Please refer below.
On 7/15/19 5:56 PM, Jean-Jacques Hiblot wrote:
> A LED is usually powered by a voltage/current regulator. Let the LED core
> know about it. This allows the LED core to turn on or off the power supply
> as needed.
>
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@...com>
> ---
> drivers/leds/led-class.c | 15 ++++++++++++
> drivers/leds/led-core.c | 50 +++++++++++++++++++++++++++++++++++++---
> drivers/leds/leds.h | 1 +
> include/linux/leds.h | 4 ++++
> 4 files changed, 67 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index 4793e77808e2..cadd43c30d50 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -253,6 +253,7 @@ int of_led_classdev_register(struct device *parent, struct device_node *np,
> {
> char name[LED_MAX_NAME_SIZE];
> int ret;
> + struct regulator *regulator;
>
> ret = led_classdev_next_name(led_cdev->name, name, sizeof(name));
> if (ret < 0)
> @@ -272,6 +273,20 @@ int of_led_classdev_register(struct device *parent, struct device_node *np,
> dev_warn(parent, "Led %s renamed to %s due to name collision",
> led_cdev->name, dev_name(led_cdev->dev));
>
> + regulator = devm_regulator_get_optional(led_cdev->dev, "power");
> + if (IS_ERR(regulator)) {
> + if (PTR_ERR(regulator) != -ENODEV) {
> + dev_err(led_cdev->dev, "Cannot get the power supply for %s\n",
> + led_cdev->name);
> + device_unregister(led_cdev->dev);
> + mutex_unlock(&led_cdev->led_access);
> + return PTR_ERR(regulator);
> + }
> + led_cdev->regulator = NULL;
> + } else {
> + led_cdev->regulator = regulator;
> + }
> +
> if (led_cdev->flags & LED_BRIGHT_HW_CHANGED) {
> ret = led_add_brightness_hw_changed(led_cdev);
> if (ret) {
> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
> index 7107cd7e87cf..a12b880b0a2f 100644
> --- a/drivers/leds/led-core.c
> +++ b/drivers/leds/led-core.c
> @@ -23,6 +23,33 @@ EXPORT_SYMBOL_GPL(leds_list_lock);
> LIST_HEAD(leds_list);
> EXPORT_SYMBOL_GPL(leds_list);
>
> +static bool __led_need_regulator_update(struct led_classdev *led_cdev,
> + int brightness)
> +{
> + bool new_state = (brightness != LED_OFF);
> +
> + return led_cdev->regulator && led_cdev->regulator_state != new_state;
> +}
> +
> +static int __led_handle_regulator(struct led_classdev *led_cdev,
> + int brightness)
> +{
> + int rc;
> +
> + if (__led_need_regulator_update(led_cdev, brightness)) {
> +
> + if (brightness != LED_OFF)
> + rc = regulator_enable(led_cdev->regulator);
> + else
> + rc = regulator_disable(led_cdev->regulator);
> + if (rc)
> + return rc;
> +
> + led_cdev->regulator_state = (brightness != LED_OFF);
> + }
> + return 0;
> +}
> +
> static int __led_set_brightness(struct led_classdev *led_cdev,
> enum led_brightness value)
> {
> @@ -80,6 +107,7 @@ static void led_timer_function(struct timer_list *t)
> }
>
> led_set_brightness_nosleep(led_cdev, brightness);
> + __led_handle_regulator(led_cdev, brightness);
This cannot be called from atomic context since regulator_enable/disable
use mutex beneath, that can sleep on contention. Therefore this call
has to be made in two places instead:
__led_set_brightness()
__led_set_brightness_blocking()
>
> /* Return in next iteration if led is in one-shot mode and we are in
> * the final blink state so that the led is toggled each delay_on +
> @@ -115,6 +143,8 @@ static void set_brightness_delayed(struct work_struct *ws)
> if (ret == -ENOTSUPP)
> ret = __led_set_brightness_blocking(led_cdev,
> led_cdev->delayed_set_value);
> + __led_handle_regulator(led_cdev, led_cdev->delayed_set_value);
> +
> if (ret < 0 &&
> /* LED HW might have been unplugged, therefore don't warn */
> !(ret == -ENODEV && (led_cdev->flags & LED_UNREGISTERING) &&
> @@ -141,6 +171,7 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
> /* never on - just set to off */
> if (!delay_on) {
> led_set_brightness_nosleep(led_cdev, LED_OFF);
> + __led_handle_regulator(led_cdev, LED_OFF);
> return;
> }
>
> @@ -148,6 +179,7 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
> if (!delay_off) {
> led_set_brightness_nosleep(led_cdev,
> led_cdev->blink_brightness);
> + __led_handle_regulator(led_cdev, led_cdev->blink_brightness);
> return;
> }
>
> @@ -256,8 +288,14 @@ void led_set_brightness_nopm(struct led_classdev *led_cdev,
> enum led_brightness value)
> {
> /* Use brightness_set op if available, it is guaranteed not to sleep */
> - if (!__led_set_brightness(led_cdev, value))
> - return;
> + if (!__led_set_brightness(led_cdev, value)) {
> + /*
> + * if regulator state doesn't need to be changed, that is all/
> + * Otherwise delegate the change to a work queue
> + */
> + if (!__led_need_regulator_update(led_cdev, value))
> + return;
> + }
>
> /* If brightness setting can sleep, delegate it to a work queue task */
> led_cdev->delayed_set_value = value;
> @@ -280,6 +318,8 @@ EXPORT_SYMBOL_GPL(led_set_brightness_nosleep);
> int led_set_brightness_sync(struct led_classdev *led_cdev,
> enum led_brightness value)
> {
> + int ret;
> +
> if (led_cdev->blink_delay_on || led_cdev->blink_delay_off)
> return -EBUSY;
>
> @@ -288,7 +328,11 @@ int led_set_brightness_sync(struct led_classdev *led_cdev,
> if (led_cdev->flags & LED_SUSPENDED)
> return 0;
>
> - return __led_set_brightness_blocking(led_cdev, led_cdev->brightness);
> + ret = __led_set_brightness_blocking(led_cdev, led_cdev->brightness);
> + if (ret)
> + return ret;
> +
> + return __led_handle_regulator(led_cdev, led_cdev->brightness);
> }
> EXPORT_SYMBOL_GPL(led_set_brightness_sync);
>
> diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
> index 47b229469069..5aa5c038bd38 100644
> --- a/drivers/leds/leds.h
> +++ b/drivers/leds/leds.h
> @@ -11,6 +11,7 @@
>
> #include <linux/rwsem.h>
> #include <linux/leds.h>
> +#include <linux/regulator/consumer.h>
>
> static inline int led_get_brightness(struct led_classdev *led_cdev)
> {
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index 9b2bf574a17a..bee8e3f8dddd 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -123,6 +123,10 @@ struct led_classdev {
>
> /* Ensures consistent access to the LED Flash Class device */
> struct mutex led_access;
> +
> + /* regulator */
> + struct regulator *regulator;
> + bool regulator_state;
> };
>
> extern int of_led_classdev_register(struct device *parent,
>
--
Best regards,
Jacek Anaszewski
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