linux-kernel - Re: [PATCH] leds: fix brightness changing when software blinking is active

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Date:	Thu, 14 May 2015 12:33:48 +0200
From:	Jacek Anaszewski <j.anaszewski@...sung.com>
To:	Stas Sergeev <stsp@...t.ru>
Cc:	linux-leds@...r.kernel.org,
	Linux kernel <linux-kernel@...r.kernel.org>,
	Bryan Wu <cooloney@...il.com>,
	Richard Purdie <rpurdie@...ys.net>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Stas Sergeev <stsp@...rs.sourceforge.net>
Subject: Re: [PATCH] leds: fix brightness changing when software blinking is
 active

On 05/14/2015 11:45 AM, Stas Sergeev wrote:
> 14.05.2015 11:44, Jacek Anaszewski пишет:
>>
>>>        if (led_cdev->blink_delay_on || led_cdev->blink_delay_off) {
>>>            led_cdev->delayed_set_value = brightness;
>>> -        schedule_work(&led_cdev->set_brightness_work);
>>
>> This line is still required. Please refer to the patch d23a22a74.
> But I really want to get rid of this line and
> vacate the work-queue, so that in the future the
> per-driver work-queues can be replaced with this.

set_brightness_delayed functions can be used for this as well.
It would only need to be extended.

> Why do you think it is still needed?
> Are there any valid cases where you need to disable the
> soft-blink from hard-irq context? IMHO the soft-blink is
> only disabled as a result of user's actions, which is not
> in a hard-irq context.
> Could you please explain the use-case?
>
>>>        /* Stop blinking */
>>> +    led_stop_software_blink(led_cdev);
>> This won't be needed.
> Indeed, but with these changes there should be no requirement
> for disabling a soft-blink from hard-irq context, which is what
> I really wanted to have. What am I missing?
>

Please look at this [1]. Author mentions setting brightness
from sound-card irq handler.

[1] http://www.spinics.net/lists/linux-leds/msg00006.html

-- 
Best Regards,
Jacek Anaszewski
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