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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 29 Jul 2009 16:20:41 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Pavel Machek <pavel@....cz>
Cc:	Zhang Rui <rui.zhang@...el.com>,
	Richard Purdie <rpurdie@...ys.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"lenb@...nel.org" <lenb@...nel.org>,
	"corentincj@...aif.net" <corentincj@...aif.net>
Subject: Re: [PATCH 1/3] backlight: Allow drivers to update the core, and
	generate events on changes

On Wed, Jul 29, 2009 at 05:05:24PM +0200, Pavel Machek wrote:
> > No, I mean that the only default policy you could reasonably have in the 
> > kernel would be tying the backlight directly to the ALS. And that sucks. 
> > You need some degree of smoothing, and that's a job better left to 
> > userspace.
> 
> How would that be done? Wake up userspace 100times a second so it can
> read an integer and ardd it to running average?

I don't think you'd need more than once a second, possibly modified by 
the size of the change since the last measurement. Response doesn't need 
to be immediate.

> Is ALS device stupid sensor, or can it do some smoothing/watermarks
> itself?

Generally stupid.

-- 
Matthew Garrett | mjg59@...f.ucam.org
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/