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

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Date:	Thu, 14 May 2015 14:52:42 +0300
From:	Stas Sergeev <stsp@...t.ru>
To:	Jacek Anaszewski <j.anaszewski@...sung.com>
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

14.05.2015 14:03, Stas Sergeev пишет:
> 14.05.2015 13:33, Jacek Anaszewski пишет:
>>> 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
> He points to the following (out-of-tree??) code:
> ---
>         if ((jiffies / HZ / 2) & 1)
>                 led_trigger_blink_oneshot(ledtrig_ide,
>                                 &ide_blink_delay, &ide_blink_delay, 0);
>         if ((jiffies / HZ / 4) & 1)
>                 led_trigger_event(ledtrig_ide, 100);
>         if ((jiffies / HZ / 8) & 1)
>                 led_trigger_event(ledtrig_ide, 0);
> ---
> I think the problem was that oneshot_trig_deactivate() was
> not doing led_stop_software_blink(led_cdev), and so he needed
> a work-queue for switching out from oneshot trigger.
> My patch fixes exactly that: now oneshot trigger does the
> proper cleanup itself.
> Do you think my patch is not enough to handle this case?
Likely not, if he switches triggers in hard-irq context.
Though I wonder if it is important to care about the out-of-tree
code that could use the work-queue itself?
Anyway, I think I should split the patch to the fix and
the cleanup, to make the life easier.
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