Re: [PATCH 1/2] leds: Add control of the voltage/current regulator to the LED core
From: Daniel Thompson
Date: Mon Jul 15 2019 - 05:24:14 EST
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,
> > > dev_warn(parent, "Led %s renamed to %s due to name collision",
> > > 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.
>
>
>
> >
> > > + if (IS_ERR(led_cdev->regulator)) {
> > > + 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(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!
Daniel.
>
>
> >
> > I prefer to keep it optional. Many LED drivers are connected to fixed
> > non-managed supplies.
> >
> > > + }
> > > +
> > > 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..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,
> > > + int brightness)
> > > +{
> > > + bool new_regulator_state = (brightness != LED_OFF);
> > > +
> > > + return led_cdev->regulator_state != new_regulator_state;
> > > +}
> > > +
> > > +static int __led_handle_regulator(struct led_classdev *led_cdev,
> > > + int brightness)
> > > +{
> > > + if (__led_need_regulator_update(led_cdev, brightness)) {
> > > + int ret;
> >
> > Prefer to this to be moved up.
> ok
> >
> > > +
> > > + if (brightness != LED_OFF)
> > > + ret = regulator_enable(led_cdev->regulator);
> > > + else
> > > + ret = regulator_disable(led_cdev->regulator);
> > > + if (ret)
> > > + return ret;
> > new line
> > > + 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 +106,7 @@ static void led_timer_function(struct timer_list *t)
> > > }
> > > led_set_brightness_nosleep(led_cdev, brightness);
> > > + __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.
> >
> >
> > > /* 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 +142,8 @@ 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 +170,7 @@ 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 +178,7 @@ 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 +287,14 @@ 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 +317,8 @@ 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 +327,15 @@ 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;
> > > +
> > > + ret = __led_handle_regulator(led_cdev, led_cdev->brightness);
> >
> > Can't you just return here?
>
> ok
>
>
> thanks for the review
>
> JJ
>
> >
> > Dan
> >
> > > + if (ret)
> > > + return ret;
> > > +
> > > + 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 {
> > > /* 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,