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SubjectRe: [PATCH] Let chip-driver set brightness if, software blink not used.
On 05/18/2016 12:33 PM, Tony Makkiel wrote:
>
>
> On 18/05/16 10:03, Jacek Anaszewski wrote:
>> Hi Tony,
>>
>> Thanks for the patch. I'd like to improve the commit message.
>>
>> Please let me know if you have any suggestions related to the below:
>>
>> led: core: Fix brightness setting upon hardware blinking enabled
>>
>> Commit 76931edd54 ('leds: fix brightness changing when software blinking
>> is active') changed the semantics of led_set_brightness() which according
>> to the documentation should disable blinking on any brightness setting.
>> Moreover it made it different for soft blink case, where it was allowed
>> for blink brightness change, and for hardware blink case, where setting
>> any brightness greater than 0 was ignored.
>>
>> While the change itself is against the documentation claims, it was driven
>> also by the fact that timer trigger remained active after turning blinking
>> off. Fixing that would have required major refactoring in the led-core,
>> led-class, and led-triggers because of cyclic dependencies.
>>
>> Finally, it has been decided that allowing for brightness change during
>> blinking is beneficial as it can be accomplished without disturbing
>> blink rhythm.
>>
>> The change in brightness setting semantics will not affect existing
>> LED class drivers that implement blink_set op thanks to the LED_BLINK_SW
>> flag introduced by this patch. The flag state will be from now on checked
>> in led_set_brightness() which will allow to distinguish between hardware
>> and software blink mode. In the former case the control will be passed
>> directly to the drivers which apply their semantics on brightness set,
>> which is disable the blinking in case of most such drivers. New drivers
>> will apply new semantics and just change the brightness while hardware
>> blinking is on, if possible.
>>
>> Due to the later LED core improvements this patch can't be applied directly
>> on the patch that originally introduced the problem, but to the later one,
>> that touched the affected code.
>>
>> Fixes: f1e80c07416a ("leds: core: Add two new LED_BLINK_ flags")
>> Signed-off-by: Tony Makkiel <tony.makkiel@daqri.com>
>> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
>>
>>
> It looks good to me. Do you want me to resubmit the patch with new commit message?
> Or can you edit it while merging the patch.

Yes please, if it's not a problem.

>> We will need also to modify the documentation, but this can
>> be done in a separate patch.
>
> Will make another patch for it. Does the following look ok?
>
> diff --git a/Documentation/leds/leds-class.txt b/Documentation/leds/leds-class.txt
> index d406d98..44f5e6b 100644
> --- a/Documentation/leds/leds-class.txt
> +++ b/Documentation/leds/leds-class.txt
> @@ -74,8 +74,8 @@ blink_set() function (see <linux/leds.h>). To set an LED to blinking,
> however, it is better to use the API function led_blink_set(), as it
> will check and implement software fallback if necessary.
>
> -To turn off blinking again, use the API function led_brightness_set()
> -as that will not just set the LED brightness but also stop any software
> +To turn off blinking, use the API function led_brightness_set()
> +with brightness value LED_OFF, which should stop any software
> timers that may have been required for blinking.

Seems good.

> The blink_set() function should choose a user friendly blinking value
>
>>
>> On 05/17/2016 06:28 PM, Tony Makkiel wrote:
>>> With this patch, chip drivers will be given option to
>>> set brightness while, blink is active.
>>>
>>> Signed-off-by: Tony Makkiel <tony.makkiel@daqri.com>
>>> ---
>>> drivers/leds/led-core.c | 7 +++++--
>>> include/linux/leds.h | 19 ++++++++++---------
>>> 2 files changed, 15 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
>>> index 3495d5d..b595eb9 100644
>>> --- a/drivers/leds/led-core.c
>>> +++ b/drivers/leds/led-core.c
>>> @@ -53,11 +53,12 @@ static void led_timer_function(unsigned long data)
>>>
>>> if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
>>> led_set_brightness_nosleep(led_cdev, LED_OFF);
>>> + led_cdev->flags &= ~LED_BLINK_SW;
>>> return;
>>> }
>>>
>>> if (led_cdev->flags & LED_BLINK_ONESHOT_STOP) {
>>> - led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
>>> + led_cdev->flags &= ~(LED_BLINK_ONESHOT_STOP | LED_BLINK_SW);
>>> return;
>>> }
>>>
>>> @@ -151,6 +152,7 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
>>> return;
>>> }
>>>
>>> + led_cdev->flags |= LED_BLINK_SW;
>>> mod_timer(&led_cdev->blink_timer, jiffies + 1);
>>> }
>>>
>>> @@ -219,6 +221,7 @@ void led_stop_software_blink(struct led_classdev *led_cdev)
>>> del_timer_sync(&led_cdev->blink_timer);
>>> led_cdev->blink_delay_on = 0;
>>> led_cdev->blink_delay_off = 0;
>>> + led_cdev->flags &= ~LED_BLINK_SW;
>>> }
>>> EXPORT_SYMBOL_GPL(led_stop_software_blink);
>>>
>>> @@ -229,7 +232,7 @@ void led_set_brightness(struct led_classdev *led_cdev,
>>> * In case blinking is on delay brightness setting
>>
>> We need to make this comment more precise:
>
> Will include the following along with documentation patch, unless require modification.
>
> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
> index b595eb9..f3af7a6 100644
> --- a/drivers/leds/led-core.c
> +++ b/drivers/leds/led-core.c
> @@ -229,7 +229,7 @@ void led_set_brightness(struct led_classdev *led_cdev,
> enum led_brightness brightness)
> {
> /*
> - * In case blinking is on delay brightness setting
> + * If software blink active, delay brightness setting

s/active/is active/

> * until the next timer tick.
> */
> if (led_cdev->flags & LED_BLINK_SW) {
>
>>
>> s/blinking/soft blink/g
>>
>>> * until the next timer tick.
>>> */
>>> - if (led_cdev->blink_delay_on || led_cdev->blink_delay_off) {
>>> + if (led_cdev->flags & LED_BLINK_SW) {
>>> /*
>>> * If we need to disable soft blinking delegate this to the
>>> * work queue task to avoid problems in case we are called
>>> diff --git a/include/linux/leds.h b/include/linux/leds.h
>>> index d2b1306..99b1f0b 100644
>>> --- a/include/linux/leds.h
>>> +++ b/include/linux/leds.h
>>> @@ -42,15 +42,16 @@ struct led_classdev {
>>> #define LED_UNREGISTERING (1 << 1)
>>> /* Upper 16 bits reflect control information */
>>> #define LED_CORE_SUSPENDRESUME (1 << 16)
>>> -#define LED_BLINK_ONESHOT (1 << 17)
>>> -#define LED_BLINK_ONESHOT_STOP (1 << 18)
>>> -#define LED_BLINK_INVERT (1 << 19)
>>> -#define LED_BLINK_BRIGHTNESS_CHANGE (1 << 20)
>>> -#define LED_BLINK_DISABLE (1 << 21)
>>> -#define LED_SYSFS_DISABLE (1 << 22)
>>> -#define LED_DEV_CAP_FLASH (1 << 23)
>>> -#define LED_HW_PLUGGABLE (1 << 24)
>>> -#define LED_PANIC_INDICATOR (1 << 25)
>>> +#define LED_BLINK_SW (1 << 17)
>>> +#define LED_BLINK_ONESHOT (1 << 18)
>>> +#define LED_BLINK_ONESHOT_STOP (1 << 19)
>>> +#define LED_BLINK_INVERT (1 << 20)
>>> +#define LED_BLINK_BRIGHTNESS_CHANGE (1 << 21)
>>> +#define LED_BLINK_DISABLE (1 << 22)
>>> +#define LED_SYSFS_DISABLE (1 << 23)
>>> +#define LED_DEV_CAP_FLASH (1 << 24)
>>> +#define LED_HW_PLUGGABLE (1 << 25)
>>> +#define LED_PANIC_INDICATOR (1 << 26)
>>>
>>> /* Set LED brightness level
>>> * Must not sleep. Use brightness_set_blocking for drivers
>>>
>>
>>
>
>


--
Best regards,
Jacek Anaszewski

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