Re: [PATCH] leds: put hard limit on minimum blink period for slow leds

From: Jacek Anaszewski
Date: Mon May 18 2015 - 04:28:26 EST

Hi Stas,

On 05/15/2015 06:47 PM, Stas Sergeev wrote:

Currently the timer trigger allows to set blink period as small as
1mS. But in fact the minimum period is jiffy, which is usually 10mS.
The following mail says:
http://lkml.iu.edu/hypermail/linux/kernel/1504.3/03469.html
---

Text after '---' characters is not added to the commit message.
Please use different characters for this and check how your patch
looks in git log after applying it locally.

As I mentioned before even with hr timer it wouldn't be possible
to assure that 1ms is achievable due to locking and bus latency
reasons.
---
So the limit of 10mS should be enforced for drivers that use
waiting operations, like transfers across slow bus.
This allows to stay on safe side when CONFIG_HZ is set to eg 1000.

This patch differentiates the "slow" drivers by marking them with
the new LED_BRIGHTNESS_SLOW flag. Currently every driver that uses
a work-queue in .brightness_set op, is marked as such.
The extra bonus is the possibility of a further development
aiming for software PWM for "fast" drivers.

CC: Bryan Wu <cooloney@xxxxxxxxx>
CC: Richard Purdie <rpurdie@xxxxxxxxx>
CC: Michael Hennerich <michael.hennerich@xxxxxxxxxx>
CC: Jan-Simon Moeller <jansimon.moeller@xxxxxx>
CC: Support Opensource <support.opensource@xxxxxxxxxxx>
CC: Milo Kim <milo.kim@xxxxxx>
CC: Riku Voipio <riku.voipio@xxxxxx>
CC: Jacek Anaszewski <j.anaszewski@xxxxxxxxxxx>
CC: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
CC: linux-leds@xxxxxxxxxxxxxxx
CC: linux-kernel@xxxxxxxxxxxxxxx
CC: patches@xxxxxxxxxxxxxxxxxxxxxxxxxxx

Signed-off-by: Stas Sergeev <stsp@xxxxxxxxxxxxxxxxxxxxx>
---
drivers/leds/led-core.c | 30 +++++++++++++++++++-----------
drivers/leds/led-triggers.c | 8 +++++---
drivers/leds/leds-88pm860x.c | 1 +
drivers/leds/leds-adp5520.c | 1 +
drivers/leds/leds-bd2802.c | 2 +-
drivers/leds/leds-blinkm.c | 3 ++-
drivers/leds/leds-da903x.c | 1 +
drivers/leds/leds-da9052.c | 1 +
drivers/leds/leds-dac124s085.c | 1 +
drivers/leds/leds-gpio.c | 2 ++
drivers/leds/leds-lm3533.c | 1 +
drivers/leds/leds-lm355x.c | 1 +
drivers/leds/leds-lm3642.c | 1 +
drivers/leds/leds-lp3944.c | 3 ++-
drivers/leds/leds-lp55xx-common.c | 1 +
drivers/leds/leds-lp8788.c | 1 +
drivers/leds/leds-lp8860.c | 1 +
drivers/leds/leds-lt3593.c | 1 +
drivers/leds/leds-mc13783.c | 3 ++-
drivers/leds/leds-pca9532.c | 1 +
drivers/leds/leds-pca955x.c | 1 +
drivers/leds/leds-pca963x.c | 1 +
drivers/leds/leds-pwm.c | 4 +++-
drivers/leds/leds-regulator.c | 2 +-
drivers/leds/leds-tca6507.c | 1 +
drivers/leds/leds-wm831x-status.c | 1 +
drivers/leds/leds-wm8350.c | 2 +-
drivers/leds/trigger/ledtrig-oneshot.c | 5 ++++-
drivers/leds/trigger/ledtrig-timer.c | 18 +++++++++++++-----
include/linux/leds.h | 8 ++++++--
30 files changed, 78 insertions(+), 29 deletions(-)

Please create a separate patch for each driver you modify and
add "Cc:" entries in the commit message for the authors.

LED flash class drivers also need the flag. Please rebase your
work on top of linux-next/master.

diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 9886dac..2653755 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -25,12 +25,19 @@ EXPORT_SYMBOL_GPL(leds_list_lock);
LIST_HEAD(leds_list);
EXPORT_SYMBOL_GPL(leds_list);

-static void led_set_software_blink(struct led_classdev *led_cdev,
+static int led_set_software_blink(struct led_classdev *led_cdev,
unsigned long delay_on,
unsigned long delay_off)
{
int current_brightness;

+ if (led_cdev->flags & LED_BRIGHTNESS_SLOW) {
+ if (delay_on < LED_SLOW_MIN_PERIOD)
+ return -EINVAL;
+ if (delay_off < LED_SLOW_MIN_PERIOD)
+ return -EINVAL;
+ }
+

How about "return -ERANGE" in both cases?

current_brightness = led_get_brightness(led_cdev);
if (current_brightness)
led_cdev->blink_brightness = current_brightness;
@@ -43,36 +50,37 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
/* never on - just set to off */
if (!delay_on) {
led_set_brightness_async(led_cdev, LED_OFF);
- return;
+ return 0;
}

/* never off - just set to brightness */
if (!delay_off) {
led_set_brightness_async(led_cdev, led_cdev->blink_brightness);
- return;
+ return 0;
}

mod_timer(&led_cdev->blink_timer, jiffies + 1);
+ return 0;
}


-static void led_blink_setup(struct led_classdev *led_cdev,
+static int led_blink_setup(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off)
{
if (!(led_cdev->flags & LED_BLINK_ONESHOT) &&
led_cdev->blink_set &&
!led_cdev->blink_set(led_cdev, delay_on, delay_off))
- return;
+ return 0;

/* blink with 1 Hz as default if nothing specified */
if (!*delay_on && !*delay_off)
*delay_on = *delay_off = 500;

- led_set_software_blink(led_cdev, *delay_on, *delay_off);
+ return led_set_software_blink(led_cdev, *delay_on, *delay_off);
}

-void led_blink_set(struct led_classdev *led_cdev,
+int led_blink_set(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off)
{
@@ -81,18 +89,18 @@ void led_blink_set(struct led_classdev *led_cdev,
led_cdev->flags &= ~LED_BLINK_ONESHOT;
led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;

- led_blink_setup(led_cdev, delay_on, delay_off);
+ return led_blink_setup(led_cdev, delay_on, delay_off);
}
EXPORT_SYMBOL(led_blink_set);

-void led_blink_set_oneshot(struct led_classdev *led_cdev,
+int led_blink_set_oneshot(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off,
int invert)
{
if ((led_cdev->flags & LED_BLINK_ONESHOT) &&
timer_pending(&led_cdev->blink_timer))
- return;
+ return -EBUSY;

led_cdev->flags |= LED_BLINK_ONESHOT;
led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
@@ -102,7 +110,7 @@ void led_blink_set_oneshot(struct led_classdev *led_cdev,
else
led_cdev->flags &= ~LED_BLINK_INVERT;

- led_blink_setup(led_cdev, delay_on, delay_off);
+ return led_blink_setup(led_cdev, delay_on, delay_off);
}
EXPORT_SYMBOL(led_blink_set_oneshot);

diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index e8b1120..012b94c 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -272,6 +272,7 @@ static void led_trigger_blink_setup(struct led_trigger *trig,
int oneshot,
int invert)
{
+ int rc = 0;

Names of variables conveying error codes are already inconsistent in
led-triggers.c (there are 'ret' and 'err'), but let's not make things
even worse. I'd opt for 'ret' here.

struct led_classdev *led_cdev;

if (!trig)
@@ -280,12 +281,13 @@ static void led_trigger_blink_setup(struct led_trigger *trig,
read_lock(&trig->leddev_list_lock);
list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
if (oneshot)
- led_blink_set_oneshot(led_cdev, delay_on, delay_off,
- invert);
+ rc = led_blink_set_oneshot(led_cdev, delay_on,
+ delay_off, invert);
else
- led_blink_set(led_cdev, delay_on, delay_off);
+ rc = led_blink_set(led_cdev, delay_on, delay_off);
}
read_unlock(&trig->leddev_list_lock);
+ WARN_ON(rc);
}

void led_trigger_blink(struct led_trigger *trig,
diff --git a/drivers/leds/leds-88pm860x.c b/drivers/leds/leds-88pm860x.c
index 1497a09..b21e6ac 100644
--- a/drivers/leds/leds-88pm860x.c
+++ b/drivers/leds/leds-88pm860x.c
@@ -213,6 +213,7 @@ static int pm860x_led_probe(struct platform_device *pdev)
data->current_brightness = 0;
data->cdev.name = data->name;
data->cdev.brightness_set = pm860x_led_set;
+ data->cdev.flags |= LED_BRIGHTNESS_SLOW;
mutex_init(&data->lock);
INIT_WORK(&data->work, pm860x_led_work);

diff --git a/drivers/leds/leds-adp5520.c b/drivers/leds/leds-adp5520.c
index 07e66ca..f3540c2 100644
--- a/drivers/leds/leds-adp5520.c
+++ b/drivers/leds/leds-adp5520.c
@@ -137,6 +137,7 @@ static int adp5520_led_probe(struct platform_device *pdev)
led_dat->cdev.default_trigger = cur_led->default_trigger;
led_dat->cdev.brightness_set = adp5520_led_set;
led_dat->cdev.brightness = LED_OFF;
+ led_dat->cdev.flags |= LED_BRIGHTNESS_SLOW;

if (cur_led->flags & ADP5520_FLAG_LED_MASK)
led_dat->flags = cur_led->flags;
diff --git a/drivers/leds/leds-bd2802.c b/drivers/leds/leds-bd2802.c
index 6078c15..3aba6af 100644
--- a/drivers/leds/leds-bd2802.c
+++ b/drivers/leds/leds-bd2802.c
@@ -633,7 +633,7 @@ static int bd2802_register_led_classdev(struct bd2802_led *led)
led->cdev_led2b.brightness = LED_OFF;
led->cdev_led2b.brightness_set = bd2802_set_led2b_brightness;
led->cdev_led2b.blink_set = bd2802_set_led2b_blink;
- led->cdev_led2b.flags |= LED_CORE_SUSPENDRESUME;
+ led->cdev_led2b.flags |= LED_CORE_SUSPENDRESUME | LED_BRIGHTNESS_SLOW;

ret = led_classdev_register(&led->client->dev, &led->cdev_led2b);
if (ret < 0) {
diff --git a/drivers/leds/leds-blinkm.c b/drivers/leds/leds-blinkm.c
index d0452b0..e5cc289 100644
--- a/drivers/leds/leds-blinkm.c
+++ b/drivers/leds/leds-blinkm.c
@@ -668,7 +668,8 @@ static int blinkm_probe(struct i2c_client *client,
led[i]->i2c_client = client;
led[i]->id = i;
led[i]->led_cdev.max_brightness = 255;
- led[i]->led_cdev.flags = LED_CORE_SUSPENDRESUME;
+ led[i]->led_cdev.flags = LED_CORE_SUSPENDRESUME |
+ LED_BRIGHTNESS_SLOW;
atomic_set(&led[i]->active, 0);
switch (i) {
case RED:
diff --git a/drivers/leds/leds-da903x.c b/drivers/leds/leds-da903x.c
index 952ba96e..af6318f 100644
--- a/drivers/leds/leds-da903x.c
+++ b/drivers/leds/leds-da903x.c
@@ -115,6 +115,7 @@ static int da903x_led_probe(struct platform_device *pdev)
led->cdev.default_trigger = pdata->default_trigger;
led->cdev.brightness_set = da903x_led_set;
led->cdev.brightness = LED_OFF;
+ led->cdev.flags |= LED_BRIGHTNESS_SLOW;

led->id = id;
led->flags = pdata->flags;
diff --git a/drivers/leds/leds-da9052.c b/drivers/leds/leds-da9052.c
index 28291b6..0c12b46 100644
--- a/drivers/leds/leds-da9052.c
+++ b/drivers/leds/leds-da9052.c
@@ -137,6 +137,7 @@ static int da9052_led_probe(struct platform_device *pdev)
led[i].cdev.brightness = LED_OFF;
led[i].cdev.max_brightness = DA9052_MAX_BRIGHTNESS;
led[i].brightness = LED_OFF;
+ led[i].flags |= LED_BRIGHTNESS_SLOW;
led[i].led_index = pled->leds[i].flags;
led[i].da9052 = dev_get_drvdata(pdev->dev.parent);
INIT_WORK(&led[i].work, da9052_led_work);
diff --git a/drivers/leds/leds-dac124s085.c b/drivers/leds/leds-dac124s085.c
index db3ba8b..64b3ed7 100644
--- a/drivers/leds/leds-dac124s085.c
+++ b/drivers/leds/leds-dac124s085.c
@@ -88,6 +88,7 @@ static int dac124s085_probe(struct spi_device *spi)
led->ldev.brightness = LED_OFF;
led->ldev.max_brightness = 0xfff;
led->ldev.brightness_set = dac124s085_set_brightness;
+ led->ldev.flags |= LED_BRIGHTNESS_SLOW;
ret = led_classdev_register(&spi->dev, &led->ldev);
if (ret < 0)
goto eledcr;
diff --git a/drivers/leds/leds-gpio.c b/drivers/leds/leds-gpio.c
index 15eb3f8..45c0bb1 100644
--- a/drivers/leds/leds-gpio.c
+++ b/drivers/leds/leds-gpio.c
@@ -137,6 +137,8 @@ static int create_gpio_led(const struct gpio_led *template,
led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
if (!template->retain_state_suspended)
led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
+ if (led_dat->can_sleep)
+ led_dat->cdev.flags |= LED_BRIGHTNESS_SLOW;

ret = gpiod_direction_output(led_dat->gpiod, state);
if (ret < 0)
diff --git a/drivers/leds/leds-lm3533.c b/drivers/leds/leds-lm3533.c
index 6e2e020..f70cd0e 100644
--- a/drivers/leds/leds-lm3533.c
+++ b/drivers/leds/leds-lm3533.c
@@ -697,6 +697,7 @@ static int lm3533_led_probe(struct platform_device *pdev)
led->cdev.brightness_get = lm3533_led_get;
led->cdev.blink_set = lm3533_led_blink_set;
led->cdev.brightness = LED_OFF;
+ led->cdev.flags |= LED_BRIGHTNESS_SLOW;
led->cdev.groups = lm3533_led_attribute_groups,
led->id = pdev->id;

diff --git a/drivers/leds/leds-lm355x.c b/drivers/leds/leds-lm355x.c
index f5112cb..4a9948b 100644
--- a/drivers/leds/leds-lm355x.c
+++ b/drivers/leds/leds-lm355x.c
@@ -483,6 +483,7 @@ static int lm355x_probe(struct i2c_client *client,
chip->cdev_flash.name = "flash";
chip->cdev_flash.max_brightness = 16;
chip->cdev_flash.brightness_set = lm355x_strobe_brightness_set;
+ chip->cdev_flash.flags |= LED_BRIGHTNESS_SLOW;
chip->cdev_flash.default_trigger = "flash";
err = led_classdev_register((struct device *)
&client->dev, &chip->cdev_flash);
diff --git a/drivers/leds/leds-lm3642.c b/drivers/leds/leds-lm3642.c
index d3dec01..84bb319 100644
--- a/drivers/leds/leds-lm3642.c
+++ b/drivers/leds/leds-lm3642.c
@@ -375,6 +375,7 @@ static int lm3642_probe(struct i2c_client *client,
chip->cdev_flash.name = "flash";
chip->cdev_flash.max_brightness = 16;
chip->cdev_flash.brightness_set = lm3642_strobe_brightness_set;
+ chip->cdev_flash.flags |= LED_BRIGHTNESS_SLOW;
chip->cdev_flash.default_trigger = "flash";
chip->cdev_flash.groups = lm3642_flash_groups,
err = led_classdev_register((struct device *)
diff --git a/drivers/leds/leds-lp3944.c b/drivers/leds/leds-lp3944.c
index 53144fb..70b15b3 100644
--- a/drivers/leds/leds-lp3944.c
+++ b/drivers/leds/leds-lp3944.c
@@ -323,7 +323,8 @@ static int lp3944_configure(struct i2c_client *client,
led->ldev.max_brightness = 1;
led->ldev.brightness_set = lp3944_led_set_brightness;
led->ldev.blink_set = lp3944_led_set_blink;
- led->ldev.flags = LED_CORE_SUSPENDRESUME;
+ led->ldev.flags = LED_CORE_SUSPENDRESUME |
+ LED_BRIGHTNESS_SLOW;

INIT_WORK(&led->work, lp3944_led_work);
err = led_classdev_register(&client->dev, &led->ldev);
diff --git a/drivers/leds/leds-lp55xx-common.c b/drivers/leds/leds-lp55xx-common.c
index 77c26bc..02bc090 100644
--- a/drivers/leds/leds-lp55xx-common.c
+++ b/drivers/leds/leds-lp55xx-common.c
@@ -173,6 +173,7 @@ static int lp55xx_init_led(struct lp55xx_led *led,
}

led->cdev.brightness_set = lp55xx_set_brightness;
+ led->cdev.flags |= LED_BRIGHTNESS_SLOW;
led->cdev.groups = lp55xx_led_groups;

if (pdata->led_config[chan].name) {
diff --git a/drivers/leds/leds-lp8788.c b/drivers/leds/leds-lp8788.c
index 3409f03..3fe2983 100644
--- a/drivers/leds/leds-lp8788.c
+++ b/drivers/leds/leds-lp8788.c
@@ -140,6 +140,7 @@ static int lp8788_led_probe(struct platform_device *pdev)
led->lp = lp;
led->led_dev.max_brightness = MAX_BRIGHTNESS;
led->led_dev.brightness_set = lp8788_brightness_set;
+ led->led_dev.flags |= LED_BRIGHTNESS_SLOW;

led_pdata = lp->pdata ? lp->pdata->led_pdata : NULL;

diff --git a/drivers/leds/leds-lp8860.c b/drivers/leds/leds-lp8860.c
index 8c2b7fb..9270410 100644
--- a/drivers/leds/leds-lp8860.c
+++ b/drivers/leds/leds-lp8860.c
@@ -407,6 +407,7 @@ static int lp8860_probe(struct i2c_client *client,
led->led_dev.name = led->label;
led->led_dev.max_brightness = LED_FULL;
led->led_dev.brightness_set = lp8860_brightness_set;
+ led->led_dev.flags |= LED_BRIGHTNESS_SLOW;

mutex_init(&led->lock);
INIT_WORK(&led->work, lp8860_led_brightness_work);
diff --git a/drivers/leds/leds-lt3593.c b/drivers/leds/leds-lt3593.c
index 9f41124..cedc31c 100644
--- a/drivers/leds/leds-lt3593.c
+++ b/drivers/leds/leds-lt3593.c
@@ -104,6 +104,7 @@ static int create_lt3593_led(const struct gpio_led *template,

if (!template->retain_state_suspended)
led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
+ led_dat->cdev.flags |= LED_BRIGHTNESS_SLOW;

ret = devm_gpio_request_one(parent, template->gpio, state ?
GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW,
diff --git a/drivers/leds/leds-mc13783.c b/drivers/leds/leds-mc13783.c
index e2b847f..706a94f 100644
--- a/drivers/leds/leds-mc13783.c
+++ b/drivers/leds/leds-mc13783.c
@@ -256,7 +256,8 @@ static int __init mc13xxx_led_probe(struct platform_device *pdev)
leds->led[i].leds = leds;
leds->led[i].cdev.name = name;
leds->led[i].cdev.default_trigger = trig;
- leds->led[i].cdev.flags = LED_CORE_SUSPENDRESUME;
+ leds->led[i].cdev.flags = LED_CORE_SUSPENDRESUME |
+ LED_BRIGHTNESS_SLOW;
leds->led[i].cdev.brightness_set = mc13xxx_led_set;
leds->led[i].cdev.max_brightness = mc13xxx_max_brightness(id);

diff --git a/drivers/leds/leds-pca9532.c b/drivers/leds/leds-pca9532.c
index 5a6363d..e9bcd0e 100644
--- a/drivers/leds/leds-pca9532.c
+++ b/drivers/leds/leds-pca9532.c
@@ -361,6 +361,7 @@ static int pca9532_configure(struct i2c_client *client,
led->ldev.brightness = LED_OFF;
led->ldev.brightness_set = pca9532_set_brightness;
led->ldev.blink_set = pca9532_set_blink;
+ led->ldev.flags |= LED_BRIGHTNESS_SLOW;
INIT_WORK(&led->work, pca9532_led_work);
err = led_classdev_register(&client->dev, &led->ldev);
if (err < 0) {
diff --git a/drivers/leds/leds-pca955x.c b/drivers/leds/leds-pca955x.c
index c3a08b6..2a6f1e5 100644
--- a/drivers/leds/leds-pca955x.c
+++ b/drivers/leds/leds-pca955x.c
@@ -329,6 +329,7 @@ static int pca955x_probe(struct i2c_client *client,

pca955x_led->led_cdev.name = pca955x_led->name;
pca955x_led->led_cdev.brightness_set = pca955x_led_set;
+ pca955x_led->led_cdev.flags |= LED_BRIGHTNESS_SLOW;

INIT_WORK(&pca955x_led->work, pca955x_led_work);

diff --git a/drivers/leds/leds-pca963x.c b/drivers/leds/leds-pca963x.c
index bee3e1a..0b2ff27 100644
--- a/drivers/leds/leds-pca963x.c
+++ b/drivers/leds/leds-pca963x.c
@@ -409,6 +409,7 @@ static int pca963x_probe(struct i2c_client *client,

pca963x[i].led_cdev.name = pca963x[i].name;
pca963x[i].led_cdev.brightness_set = pca963x_led_set;
+ pca963x[i].led_cdev.flags |= LED_BRIGHTNESS_SLOW;

if (pdata && pdata->blink_type == PCA963X_HW_BLINK)
pca963x[i].led_cdev.blink_set = pca963x_blink_set;
diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index 1d07e3e..daff48d 100644
--- a/drivers/leds/leds-pwm.c
+++ b/drivers/leds/leds-pwm.c
@@ -122,8 +122,10 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
}

led_data->can_sleep = pwm_can_sleep(led_data->pwm);
- if (led_data->can_sleep)
+ if (led_data->can_sleep) {
INIT_WORK(&led_data->work, led_pwm_work);
+ led_data->cdev.flags |= LED_BRIGHTNESS_SLOW;
+ }

led_data->period = pwm_get_period(led_data->pwm);
if (!led_data->period && (led->pwm_period_ns > 0))
diff --git a/drivers/leds/leds-regulator.c b/drivers/leds/leds-regulator.c
index ffc2139..3b898fb 100644
--- a/drivers/leds/leds-regulator.c
+++ b/drivers/leds/leds-regulator.c
@@ -173,7 +173,7 @@ static int regulator_led_probe(struct platform_device *pdev)

led->cdev.brightness_set = regulator_led_brightness_set;
led->cdev.name = pdata->name;
- led->cdev.flags |= LED_CORE_SUSPENDRESUME;
+ led->cdev.flags |= LED_CORE_SUSPENDRESUME | LED_BRIGHTNESS_SLOW;
led->vcc = vcc;

/* to handle correctly an already enabled regulator */
diff --git a/drivers/leds/leds-tca6507.c b/drivers/leds/leds-tca6507.c
index 20fa8e7..8209b0d 100644
--- a/drivers/leds/leds-tca6507.c
+++ b/drivers/leds/leds-tca6507.c
@@ -788,6 +788,7 @@ static int tca6507_probe(struct i2c_client *client,
= pdata->leds.leds[i].default_trigger;
l->led_cdev.brightness_set = tca6507_brightness_set;
l->led_cdev.blink_set = tca6507_blink_set;
+ l->led_cdev.flags |= LED_BRIGHTNESS_SLOW;
l->bank = -1;
err = led_classdev_register(&client->dev,
&l->led_cdev);
diff --git a/drivers/leds/leds-wm831x-status.c b/drivers/leds/leds-wm831x-status.c
index 56027ef..7718dcd 100644
--- a/drivers/leds/leds-wm831x-status.c
+++ b/drivers/leds/leds-wm831x-status.c
@@ -288,6 +288,7 @@ static int wm831x_status_probe(struct platform_device *pdev)
drvdata->cdev.name = pdata.name;
drvdata->cdev.default_trigger = pdata.default_trigger;
drvdata->cdev.brightness_set = wm831x_status_set;
+ drvdata->cdev.flags |= LED_BRIGHTNESS_SLOW;
drvdata->cdev.blink_set = wm831x_status_blink_set;
drvdata->cdev.groups = wm831x_status_groups;

diff --git a/drivers/leds/leds-wm8350.c b/drivers/leds/leds-wm8350.c
index 0d12183..ad1ada3 100644
--- a/drivers/leds/leds-wm8350.c
+++ b/drivers/leds/leds-wm8350.c
@@ -235,7 +235,7 @@ static int wm8350_led_probe(struct platform_device *pdev)
led->cdev.brightness_set = wm8350_led_set;
led->cdev.default_trigger = pdata->default_trigger;
led->cdev.name = pdata->name;
- led->cdev.flags |= LED_CORE_SUSPENDRESUME;
+ led->cdev.flags |= LED_CORE_SUSPENDRESUME | LED_BRIGHTNESS_SLOW;
led->enabled = regulator_is_enabled(isink);
led->isink = isink;
led->dcdc = dcdc;
diff --git a/drivers/leds/trigger/ledtrig-oneshot.c b/drivers/leds/trigger/ledtrig-oneshot.c
index fbd02cd..ba91838 100644
--- a/drivers/leds/trigger/ledtrig-oneshot.c
+++ b/drivers/leds/trigger/ledtrig-oneshot.c
@@ -29,12 +29,15 @@ struct oneshot_trig_data {
static ssize_t led_shot(struct device *dev,
struct device_attribute *attr, const char *buf, size_t size)
{
+ ssize_t ret;
struct led_classdev *led_cdev = dev_get_drvdata(dev);
struct oneshot_trig_data *oneshot_data = led_cdev->trigger_data;

- led_blink_set_oneshot(led_cdev,
+ ret = led_blink_set_oneshot(led_cdev,
&led_cdev->blink_delay_on, &led_cdev->blink_delay_off,
oneshot_data->invert);
+ if (ret)
+ return ret;

/* content is ignored */
return size;
diff --git a/drivers/leds/trigger/ledtrig-timer.c b/drivers/leds/trigger/ledtrig-timer.c
index 8d09327..edc0c7f 100644
--- a/drivers/leds/trigger/ledtrig-timer.c
+++ b/drivers/leds/trigger/ledtrig-timer.c
@@ -31,13 +31,15 @@ static ssize_t led_delay_on_store(struct device *dev,
{
struct led_classdev *led_cdev = dev_get_drvdata(dev);
unsigned long state;
- ssize_t ret = -EINVAL;
+ ssize_t ret;

ret = kstrtoul(buf, 10, &state);
if (ret)
return ret;

- led_blink_set(led_cdev, &state, &led_cdev->blink_delay_off);
+ ret = led_blink_set(led_cdev, &state, &led_cdev->blink_delay_off);
+ if (ret)
+ return ret;
led_cdev->blink_delay_on = state;

return size;
@@ -56,13 +58,15 @@ static ssize_t led_delay_off_store(struct device *dev,
{
struct led_classdev *led_cdev = dev_get_drvdata(dev);
unsigned long state;
- ssize_t ret = -EINVAL;
+ ssize_t ret;

ret = kstrtoul(buf, 10, &state);
if (ret)
return ret;

- led_blink_set(led_cdev, &led_cdev->blink_delay_on, &state);
+ ret = led_blink_set(led_cdev, &led_cdev->blink_delay_on, &state);
+ if (ret)
+ return ret;
led_cdev->blink_delay_off = state;

return size;
@@ -84,12 +88,16 @@ static void timer_trig_activate(struct led_classdev *led_cdev)
if (rc)
goto err_out_delayon;

- led_blink_set(led_cdev, &led_cdev->blink_delay_on,
+ rc = led_blink_set(led_cdev, &led_cdev->blink_delay_on,
&led_cdev->blink_delay_off);
+ if (rc)
+ goto err_out_delayoff;
led_cdev->activated = true;

return;

+err_out_delayoff:
+ device_remove_file(led_cdev->dev, &dev_attr_delay_off);
err_out_delayon:
device_remove_file(led_cdev->dev, &dev_attr_delay_on);
}
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 9a2b000..356b8d1 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -47,6 +47,10 @@ struct led_classdev {
#define SET_BRIGHTNESS_ASYNC (1 << 21)
#define SET_BRIGHTNESS_SYNC (1 << 22)
#define LED_DEV_CAP_FLASH (1 << 23)
+#define LED_BRIGHTNESS_SLOW (1 << 24)
+
+/* safe period value for slow leds is 10mS */
+#define LED_SLOW_MIN_PERIOD 10

/* Set LED brightness level */
/* Must not sleep, use a workqueue if needed */
@@ -127,7 +131,7 @@ extern void led_classdev_resume(struct led_classdev *led_cdev);
* led_cdev->brightness_set() will not stop the blinking,
* use led_classdev_brightness_set() instead.
*/
-extern void led_blink_set(struct led_classdev *led_cdev,
+extern int led_blink_set(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off);
/**
@@ -144,7 +148,7 @@ extern void led_blink_set(struct led_classdev *led_cdev,
* If invert is set, led blinks for delay_off first, then for
* delay_on and leave the led on after the on-off cycle.
*/
-extern void led_blink_set_oneshot(struct led_classdev *led_cdev,
+extern int led_blink_set_oneshot(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off,
int invert);


"Returns:" entry is now missing in the documentation of both functions.

--
Best Regards,
Jacek Anaszewski
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