Re: [PATCH 1/2] leds: Add control of the voltage/current regulator to the LED core

From: Jean-Jacques Hiblot
Date: Mon Jul 15 2019 - 05:01:44 EST

Hi Dan,

On 12/07/2019 20:49, Dan Murphy wrote:
JJ

On 7/8/19 5:35 AM, Jean-Jacques Hiblot wrote:
A LED is usually powered by a voltage/current regulator. Let the LED core
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@xxxxxx>
---
 drivers/leds/led-class.c | 10 ++++++++
 drivers/leds/led-core.c | 53 +++++++++++++++++++++++++++++++++++++---
 include/linux/leds.h | 4 +++
 3 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 4793e77808e2..e01b2d982564 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -17,6 +17,7 @@
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/timer.h>
+#include <linux/regulator/consumer.h>

What if you move this to leds.h so core and class can both include it.


 #include <uapi/linux/uleds.h>
 #include "leds.h"
 @@ -272,6 +273,15 @@ int of_led_classdev_register(struct device *parent, struct device_node *np,
ÂÂÂÂÂÂÂÂÂ dev_warn(parent, "Led %s renamed to %s due to name collision",
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ led_cdev->name, dev_name(led_cdev->dev));
 + led_cdev->regulator = devm_regulator_get(led_cdev->dev, "power");

Is the regulator always going to be called power?

Actually in the dts, that will be "power-supply". I lacked the imagination to come up with a better name.




+ÂÂÂ if (IS_ERR(led_cdev->regulator)) {
+ÂÂÂÂÂÂÂ dev_err(led_cdev->dev, "Cannot get the power supply for %s\n",
+ÂÂÂÂÂÂÂÂÂÂÂ led_cdev->name);
+ÂÂÂÂÂÂÂ device_unregister(led_cdev->dev);
+ÂÂÂÂÂÂÂ mutex_unlock(&led_cdev->led_access);
+ÂÂÂÂÂÂÂ return PTR_ERR(led_cdev->regulator);

This is listed as optional in the DT doc. This appears to be required.

The regulator core will provide a dummy regulator if none is given in the device tree. I would rather have an error in that case, but that is not how it works.



I prefer to keep it optional. Many LED drivers are connected to fixed non-managed supplies.

+ÂÂÂ }
+
ÂÂÂÂÂ if (led_cdev->flags & LED_BRIGHT_HW_CHANGED) {
ÂÂÂÂÂÂÂÂÂ ret = led_add_brightness_hw_changed(led_cdev);
ÂÂÂÂÂÂÂÂÂ if (ret) {
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 7107cd7e87cf..139de6b08cad 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -16,6 +16,7 @@
 #include <linux/rwsem.h>
 #include <linux/slab.h>
 #include "leds.h"
+#include <linux/regulator/consumer.h>
  DECLARE_RWSEM(leds_list_lock);
 EXPORT_SYMBOL_GPL(leds_list_lock);
@@ -23,6 +24,31 @@ 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,
+ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ int brightness)
+{
+ÂÂÂ bool new_regulator_state = (brightness != LED_OFF);
+
+ÂÂÂ return led_cdev->regulator_state != new_regulator_state;
+}
+
+static int __led_handle_regulator(struct led_classdev *led_cdev,
+ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ int brightness)
+{
+ÂÂÂ if (__led_need_regulator_update(led_cdev, brightness)) {
+ÂÂÂÂÂÂÂ int ret;

Prefer to this to be moved up.
ok

+
+ÂÂÂÂÂÂÂ if (brightness != LED_OFF)
+ÂÂÂÂÂÂÂÂÂÂÂ ret = regulator_enable(led_cdev->regulator);
+ÂÂÂÂÂÂÂ else
+ÂÂÂÂÂÂÂÂÂÂÂ ret = regulator_disable(led_cdev->regulator);
+ÂÂÂÂÂÂÂ if (ret)
+ÂÂÂÂÂÂÂÂÂÂÂ return ret;
new line
+ÂÂÂÂÂÂÂ led_cdev->regulator_state = (brightness != LED_OFF);
+ÂÂÂ }
+ÂÂÂ return 0;
+}
+
 static int __led_set_brightness(struct led_classdev *led_cdev,
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ enum led_brightness value)
 {
@@ -80,6 +106,7 @@ static void led_timer_function(struct timer_list *t)
ÂÂÂÂÂ }
 Â led_set_brightness_nosleep(led_cdev, brightness);
+ÂÂÂ __led_handle_regulator(led_cdev, brightness);

Again this seems to indicate that the regulator is a required property for the LEDs

This needs to be made optional. And the same comment through out for every call.


 Â /* Return in next iteration if led is in one-shot mode and we are in
ÂÂÂÂÂÂ * the final blink state so that the led is toggled each delay_on +
@@ -115,6 +142,8 @@ static void set_brightness_delayed(struct work_struct *ws)
ÂÂÂÂÂ if (ret == -ENOTSUPP)
ÂÂÂÂÂÂÂÂÂ ret = __led_set_brightness_blocking(led_cdev,
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ led_cdev->delayed_set_value);
+ÂÂÂ __led_handle_regulator(led_cdev, led_cdev->delayed_set_value);
+
ÂÂÂÂÂ if (ret < 0 &&
ÂÂÂÂÂÂÂÂÂ /* LED HW might have been unplugged, therefore don't warn */
ÂÂÂÂÂÂÂÂÂ !(ret == -ENODEV && (led_cdev->flags & LED_UNREGISTERING) &&
@@ -141,6 +170,7 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
ÂÂÂÂÂ /* never on - just set to off */
ÂÂÂÂÂ if (!delay_on) {
ÂÂÂÂÂÂÂÂÂ led_set_brightness_nosleep(led_cdev, LED_OFF);
+ÂÂÂÂÂÂÂ __led_handle_regulator(led_cdev, LED_OFF);
ÂÂÂÂÂÂÂÂÂ return;
ÂÂÂÂÂ }
 @@ -148,6 +178,7 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
ÂÂÂÂÂ if (!delay_off) {
ÂÂÂÂÂÂÂÂÂ led_set_brightness_nosleep(led_cdev,
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ led_cdev->blink_brightness);
+ÂÂÂÂÂÂÂ __led_handle_regulator(led_cdev, led_cdev->blink_brightness);
ÂÂÂÂÂÂÂÂÂ return;
ÂÂÂÂÂ }
 @@ -256,8 +287,14 @@ void led_set_brightness_nopm(struct led_classdev *led_cdev,
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ enum led_brightness value)
 {
ÂÂÂÂÂ /* Use brightness_set op if available, it is guaranteed not to sleep */
-ÂÂÂ if (!__led_set_brightness(led_cdev, value))
-ÂÂÂÂÂÂÂ return;
+ÂÂÂ if (!__led_set_brightness(led_cdev, value)) {
+ÂÂÂÂÂÂÂ /*
+ÂÂÂÂÂÂÂÂ * if regulator state doesn't need to be changed, that is all/
+ÂÂÂÂÂÂÂÂ * Otherwise delegate the change to a work queue
+ÂÂÂÂÂÂÂÂ */
+ÂÂÂÂÂÂÂ if (!__led_need_regulator_update(led_cdev, value))
+ÂÂÂÂÂÂÂÂÂÂÂ return;
+ÂÂÂ }
 Â /* If brightness setting can sleep, delegate it to a work queue task */
ÂÂÂÂÂ led_cdev->delayed_set_value = value;
@@ -280,6 +317,8 @@ EXPORT_SYMBOL_GPL(led_set_brightness_nosleep);
 int led_set_brightness_sync(struct led_classdev *led_cdev,
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ enum led_brightness value)
 {
+ÂÂÂ int ret;
+
ÂÂÂÂÂ if (led_cdev->blink_delay_on || led_cdev->blink_delay_off)
ÂÂÂÂÂÂÂÂÂ return -EBUSY;
 @@ -288,7 +327,15 @@ int led_set_brightness_sync(struct led_classdev *led_cdev,
ÂÂÂÂÂ if (led_cdev->flags & LED_SUSPENDED)
ÂÂÂÂÂÂÂÂÂ return 0;
 - return __led_set_brightness_blocking(led_cdev, led_cdev->brightness);
+ÂÂÂ ret = __led_set_brightness_blocking(led_cdev, led_cdev->brightness);
+ÂÂÂ if (ret)
+ÂÂÂÂÂÂÂ return ret;
+
+ÂÂÂ ret = __led_handle_regulator(led_cdev, led_cdev->brightness);

Can't you just return here?

ok


thanks for the review

JJ


Dan

+ÂÂÂ if (ret)
+ÂÂÂÂÂÂÂ return ret;
+
+ÂÂÂ return 0;
 }
 EXPORT_SYMBOL_GPL(led_set_brightness_sync);
 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 {
 Â /* Ensures consistent access to the LED Flash Class device */
ÂÂÂÂÂ struct mutexÂÂÂÂÂÂÂ led_access;
+
+ÂÂÂ /* regulator */
+ÂÂÂ struct regulatorÂÂÂ *regulator;
+ÂÂÂ boolÂÂÂÂÂÂÂÂÂÂÂ regulator_state;
 };
  extern int of_led_classdev_register(struct device *parent,