Messages in this thread | | | Subject | Re: [PATCH v4 1/3] led: make led_set_brightness_sync() use led_set_brightness_nosleep() | From | Jean-Jacques Hiblot <> | Date | Mon, 23 Sep 2019 11:14:20 +0200 |
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Hi Jacek,
On 20/09/2019 23:10, Jacek Anaszewski wrote: > Hi Jean, > > On 9/20/19 2:25 PM, Jean-Jacques Hiblot wrote: >> Making led_set_brightness_sync() use led_set_brightness_nosleep() has 2 >> advantages: >> - works for LED controllers that do not provide brightness_set_blocking() >> - When the blocking callback is used, it uses the workqueue to update the >> LED state, removing the need for mutual exclusion between >> led_set_brightness_sync() and set_brightness_delayed(). > And third: > > - it compromises the "sync" part of the function name :-)
Making it sync is the role of the flush_work() function. It waits until the deferred work has been done.
JJ
> This function has been introduced specifically to be blocking > and have the immediate effect. Its sole client is > drivers/media/v4l2-core/v4l2-flash-led-class.c. > >> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com> >> --- >> drivers/leds/led-core.c | 12 +++++++----- >> 1 file changed, 7 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c >> index f1f718dbe0f8..50e28a8f9357 100644 >> --- a/drivers/leds/led-core.c >> +++ b/drivers/leds/led-core.c >> @@ -294,15 +294,17 @@ 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; >> >> - led_cdev->brightness = min(value, led_cdev->max_brightness); >> - >> - if (led_cdev->flags & LED_SUSPENDED) >> - return 0; >> + ret = led_set_brightness_nosleep(led_cdev, value); >> + if (!ret) >> + return ret; >> >> - return __led_set_brightness_blocking(led_cdev, led_cdev->brightness); >> + flush_work(&led_cdev->set_brightness_work); >> + return 0; >> } >> EXPORT_SYMBOL_GPL(led_set_brightness_sync); >> >>
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