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Message-ID: <9c53f54f-d0d4-50d4-09da-34389085269a@ti.com>
Date: Mon, 15 Jul 2019 11:47:08 +0200
From: Jean-Jacques Hiblot <jjhiblot@...com>
To: Daniel Thompson <daniel.thompson@...aro.org>
CC: Dan Murphy <dmurphy@...com>, <jacek.anaszewski@...il.com>,
<pavel@....cz>, <robh+dt@...nel.org>, <mark.rutland@....com>,
<linux-leds@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<devicetree@...r.kernel.org>
Subject: Re: [PATCH 1/2] leds: Add control of the voltage/current regulator to
the LED core
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@...com>
>>>> ---
>>>> 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!
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.
>>>
>>>> + }
>>>> +
>>>> 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,
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