linux-kernel - Re: [PATCH 1/3] backlight: Allow drivers to update the core, and generate events on changes

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Message-ID: <20090714132152.GA22521@srcf.ucam.org>
Date:	Tue, 14 Jul 2009 14:21:52 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Henrique de Moraes Holschuh <hmh@....eng.br>
Cc:	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	rpurdie@...ys.net, lenb@...nel.org, rui.zhang@...el.com,
	corentincj@...aif.net
Subject: Re: [PATCH 1/3] backlight: Allow drivers to update the core, and
	generate events on changes

On Tue, Jul 14, 2009 at 07:30:07AM -0300, Henrique de Moraes Holschuh wrote:
> On Mon, 13 Jul 2009, Matthew Garrett wrote:
> > Certain hardware will send us events when the backlight brightness
> > changes. Add a function to update the value in the core, and
> > additionally send a uevent so that userspace can pop up appropriate
> > UI. The uevents are flagged depending on whether the update originated
> > in the kernel or from userspace, making it easier to only display UI
> > at the appropriate time.
> 
> Any reasons to not do it using poll() support (since sysfs has it)?  Or at
> least, do both poll and uevents?

More code? It doesn't really seem necessary.

> Other than that, I like the idea a lot.  thinkpad-acpi will use this event
> support.

Good, that's one of the use-cases I wanted to deal with - but the hotkey 
mask stuff is complicated enough that I hadn't got round to touching 
that yet. The combination of this and the ALSA mixer code should get us 
full notification.

-- 
Matthew Garrett | mjg59@...f.ucam.org
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