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 - 05:47:24 EST
On 15/07/2019 11:24, Daniel Thompson wrote:
On Mon, Jul 15, 2019 at 11:01:29AM +0200, Jean-Jacques Hiblot wrote:
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.
If you actively wanted to get -ENODEV back when there is no regulator
then you can use devm_regulator_get_optional() for that.
However perhaps be careful what you wish for. If you use get_optional()
then you will have to sprinkle NULL or IS_ERR() checks everywhere. I'd
favour using the current approach!
Thanks for the info. I think I'll use the get_optionnal(). That will add
a bit of complexity, but it will avoid deferring some work in
led_set_brightness_nopm() when it is not needed.
JJ
Daniel.
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,