From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753393Ab1KTLWw (ORCPT ); Sun, 20 Nov 2011 06:22:52 -0500 Received: from cantor2.suse.de ([195.135.220.15]:55522 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753082Ab1KTLWv (ORCPT ); Sun, 20 Nov 2011 06:22:51 -0500 Date: Sun, 20 Nov 2011 12:22:50 +0100 Message-ID: From: Takashi Iwai To: Keith Packard Cc: Daniel Mack , Chris Wilson , Jesse Barnes , harald@redhat.com, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/i915: Fix invalid backpanel values for GEN3 or older chips In-Reply-To: <867h2wklln.fsf@sumi.keithp.com> References: <861ut5mdvn.fsf@sumi.keithp.com> <867h2wklln.fsf@sumi.keithp.com> User-Agent: Wanderlust/2.15.6 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.7 Emacs/23.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org At Sat, 19 Nov 2011 10:34:12 -0800, Keith Packard wrote: > > [1 ] > On Sat, 19 Nov 2011 11:05:05 +0100, Takashi Iwai wrote: > > > Maybe it'd be better to mention that actually setting bit-0 caused a > > blank screen on some machines. > > Was that caused by *just* setting bit zero? Or was it caused by setting > the duty cycle to 0xffff, in which case it would be larger than the > maximum value? > > I'll clean up the commit log message with your answer and then push this out. According to Daniels' original post: On 11/04/2011 03:36 PM, Daniel Mack wrote: > I'm facing a bug on a Samsung X20 notebook which features an i915 > chipset (output of 'lspci -v' attached). > > The effect is that setting the backlight to odd values causes the value > to be misinterpreted. Harald Hoyer (cc:) had the same thing on a Netbook > (I don't recall which model it was). > > So this will turn the backlight to full brightness: > > # cat /sys/class/backlight/intel_backlight/max_brightness > 29750 > # echo 29750 > /sys/class/backlight/intel_backlight/brightness > > However, writing 29749 will turn the display backlight off, and 29748 > appears to be the next valid lower value. So, writing bit-0 caused a problem, as it seems. Takashi From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: [PATCH] drm/i915: Fix invalid backpanel values for GEN3 or older chips Date: Sun, 20 Nov 2011 12:22:50 +0100 Message-ID: References: <861ut5mdvn.fsf@sumi.keithp.com> <867h2wklln.fsf@sumi.keithp.com> Mime-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) by gabe.freedesktop.org (Postfix) with ESMTP id C51659E872 for ; Sun, 20 Nov 2011 03:22:51 -0800 (PST) In-Reply-To: <867h2wklln.fsf@sumi.keithp.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Keith Packard Cc: intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, Daniel Mack , harald@redhat.com List-Id: intel-gfx@lists.freedesktop.org At Sat, 19 Nov 2011 10:34:12 -0800, Keith Packard wrote: > > [1 ] > On Sat, 19 Nov 2011 11:05:05 +0100, Takashi Iwai wrote: > > > Maybe it'd be better to mention that actually setting bit-0 caused a > > blank screen on some machines. > > Was that caused by *just* setting bit zero? Or was it caused by setting > the duty cycle to 0xffff, in which case it would be larger than the > maximum value? > > I'll clean up the commit log message with your answer and then push this out. According to Daniels' original post: On 11/04/2011 03:36 PM, Daniel Mack wrote: > I'm facing a bug on a Samsung X20 notebook which features an i915 > chipset (output of 'lspci -v' attached). > > The effect is that setting the backlight to odd values causes the value > to be misinterpreted. Harald Hoyer (cc:) had the same thing on a Netbook > (I don't recall which model it was). > > So this will turn the backlight to full brightness: > > # cat /sys/class/backlight/intel_backlight/max_brightness > 29750 > # echo 29750 > /sys/class/backlight/intel_backlight/brightness > > However, writing 29749 will turn the display backlight off, and 29748 > appears to be the next valid lower value. So, writing bit-0 caused a problem, as it seems. Takashi