From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Purdie Subject: Re: 2.6.21-rc1 dims my LCD Date: Mon, 26 Feb 2007 15:43:37 +0000 Message-ID: <1172504617.5824.102.camel@localhost.localdomain> References: <1172490091.5824.30.camel@localhost.localdomain> <20070226142157.GA2909@khazad-dum.debian.net> <1172501357.5824.91.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-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1HLi13-0003LX-Jf for linux-fbdev-devel@lists.sourceforge.net; Mon, 26 Feb 2007 07:43:53 -0800 Received: from tim.rpsys.net ([194.106.48.114] ident=0) by mail.sourceforge.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.44) id 1HLi12-0003yz-W2 for linux-fbdev-devel@lists.sourceforge.net; Mon, 26 Feb 2007 07:43:53 -0800 In-Reply-To: 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: Jiri Kosina Cc: FB-Dev , linux-kernel@vger.kernel.org, Henrique de Moraes Holschuh 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? This should come from two calls to fbcon_generic_blank() in drivers/video/console/fbcon.c with a different blank parameter and is therefore in a way outside the scope of the backlight class. It would be interesting to know why it decides to blank then immediately unblank the display though. I've cc'd the fbdev-devel list. Richard ------------------------------------------------------------------------- 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