linux-kernel - Re: [PATCH/RFC RESEND] leds: Use set_brightness_work for brightness

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Message-id: <5592944B.5020809@samsung.com>
Date:	Tue, 30 Jun 2015 15:06:19 +0200
From:	Jacek Anaszewski <j.anaszewski@...sung.com>
To:	Pavel Machek <pavel@...x.de>
Cc:	linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
	Bryan Wu <cooloney@...il.com>,
	Richard Purdie <rpurdie@...ys.net>,
	Stas Sergeev <stsp@...rs.sourceforge.net>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Andreas Werner <andreas.werner@....de>,
	Andrew Lunn <andrew@...n.ch>,
	Antonio Ospite <ospite@...denti.unina.it>,
	Atsushi Nemoto <anemo@....ocn.ne.jp>,
	Ben Dooks <ben@...tec.co.uk>, Chris Boot <bootc@...tc.net>,
	Dan Murphy <dmurphy@...com>,
	Daniel Jeong <daniel.jeong@...com>,
	Daniel Mack <daniel@...que.org>,
	"David S. Miller" <davem@...emloft.net>,
	Fabio Baltieri <fabio.baltieri@...il.com>,
	Felipe Balbi <balbi@...com>,
	Florian Fainelli <florian@...nwrt.org>,
	"G.Shark Jeong" <gshark.jeong@...il.com>,
	Guennadi Liakhovetski <g.liakhovetski@....de>,
	Ingi Kim <ingi2.kim@...sung.com>,
	Jan-Simon Moeller <dl9pf@....de>,
	Johan Hovold <johan@...nel.org>, John Lenz <lenz@...wisc.edu>,
	Jonas Gorski <jogo@...nwrt.org>,
	Kim Kyuwon <q1.kim@...sung.com>,
	Kristian Kielhofner <kris@...sk.org>,
	Kristoffer Ericson <kristoffer.ericson@...il.com>,
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	Nate Case <ncase@...-inc.com>, NeilBrown <neilb@...e.de>,
	Nick Forbes <nick.forbes@...epta.com>,
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	Peter Meerwald <p.meerwald@...-electronic.com>,
	Phil Sutter <n0-1@...ewrt.org>,
	Philippe Retornaz <philippe.retornaz@...l.ch>,
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	Rod Whitby <rod@...tby.id.au>, Dave Hansen <dave@...1.net>,
	Rodolfo Giometti <giometti@...ux.it>,
	"Sebastian A. Siewior" <bigeasy@...utronix.de>,
	Shuah Khan <shuahkhan@...il.com>,
	Simon Guinot <sguinot@...ie.com>,
	Álvaro Fernández Rojas <noltari@...il.com>
Subject: Re: [PATCH/RFC RESEND] leds: Use set_brightness_work for
 brightness_set ops that can sleep

On 06/30/2015 01:58 PM, Pavel Machek wrote:
> On Tue 2015-06-30 10:01:08, Jacek Anaszewski wrote:
>> This patch rearranges the core LED subsystem code, so that it
>> now removes from drivers the responsibility of using work queues
>> internally in case their brightness_set ops can sleep.
>> Addition of two flags: LED_BRIGHTNESS_FAST and LED_BLINK_DISABLE
>> as well as new_brightness_value property to the struct led_classdev
>> allows for employing existing set_brightness_work to do the job.
>> The modifications allow also to get rid of brightness_set_sync op,
>> as flash LED devices can now be handled properly only basing on the
>> SET_BRIGHTNESS_SYNC flag.
>
> Are you sure this is good idea?
>
> You'll now use single callback for blocking and non-blocking
> behaviour. I'm pretty sure stuff like lockdep will have some fun with
> that.

I enabled "Lock Debugging" options and didn't get any warning.
Could you describe the use case you are thinking of?

-- 
Best Regards,
Jacek Anaszewski
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