From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Antonino A. Daplas" Subject: Re: 2.6.21-rc1 dims my LCD Date: Tue, 27 Feb 2007 01:13:59 +0800 Message-ID: <1172510039.7101.3.camel@daplas> References: <1172490091.5824.30.camel@localhost.localdomain> <20070226142157.GA2909@khazad-dum.debian.net> <1172501357.5824.91.camel@localhost.localdomain> <1172504617.5824.102.camel@localhost.localdomain> Reply-To: linux-fbdev-devel@lists.sourceforge.net Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.91] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1HLjO4-00069P-Rx for linux-fbdev-devel@lists.sourceforge.net; Mon, 26 Feb 2007 09:11:45 -0800 Received: from py-out-1112.google.com ([64.233.166.182]) by mail.sourceforge.net with esmtp (Exim 4.44) id 1HLjO3-0005Wr-Fc for linux-fbdev-devel@lists.sourceforge.net; Mon, 26 Feb 2007 09:11:44 -0800 Received: by py-out-1112.google.com with SMTP id a29so737856pyi for ; Mon, 26 Feb 2007 09:11:43 -0800 (PST) In-Reply-To: <1172504617.5824.102.camel@localhost.localdomain> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-fbdev-devel-bounces@lists.sourceforge.net Errors-To: linux-fbdev-devel-bounces@lists.sourceforge.net To: linux-fbdev-devel@lists.sourceforge.net Cc: Richard Purdie , linux-kernel@vger.kernel.org, Henrique de Moraes Holschuh , Jiri Kosina On Mon, 2007-02-26 at 15:43 +0000, Richard Purdie wrote: > On Mon, 2007-02-26 at 16:24 +0100, Jiri Kosina wrote: > > On Mon, 26 Feb 2007, Richard Purdie wrote: > > > > > Jiri: I've appended a patch that should already be queued, could you > > > test and see if it solves the problem. > > > > Thanks. In the meantime I have gone through the code and I can confirm > > that this is the root cause of what I am observing. > > > > Now regarding the patch - at the time when the dim happened previously, > > currently there is a observable blink (after which the brightness is > > correct). > > The reason for the behaviour is that its turning the backlight down/off > to save power as it thinks the screen is blank. The blink therefore > makes sense as far as the backlight class is concerned and its working > as intended now. > > > I have put some debugging printk() into fb_notifier_callback(), > > and it turns out that on FB_EVENT_CONBLANK, there are two successive calls > > to backlight_update_status(), second immediately following the first one: > > > > Feb 26 15:11:14 thunder kernel: calling backlight_update_status() with bd->props.fb_blank == 1, bd->props.brightness == 0 > > Feb 26 15:11:14 thunder kernel: calling backlight_update_status() with bd->props.fb_blank == 0, bd->props.brightness == 0 > > > > Is this really a right thing to do? Well, no, the console should not blank and immediately unblank. Of course, the console can blank after some time and can be induced to unblank after a keyboard event, for example. Besides the debugging printk's, can you also add something like WARN_ON(1); so you can get a tracing too. Tony ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV