From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754682AbbAURNx (ORCPT ); Wed, 21 Jan 2015 12:13:53 -0500 Received: from mga14.intel.com ([192.55.52.115]:29911 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752595AbbAURNr (ORCPT ); Wed, 21 Jan 2015 12:13:47 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,442,1418112000"; d="scan'208";a="640504873" From: Jani Nikula To: Jeremiah Mahler Cc: Daniel Vetter , David Airlie , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Jeremiah Mahler Subject: Re: [PATCH v2] drm/i915: fix inconsistent brightness after resume In-Reply-To: <1421089263-30398-1-git-send-email-jmmahler@gmail.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20150112184701.GA23217@hudson.localdomain> <1421089263-30398-1-git-send-email-jmmahler@gmail.com> User-Agent: Notmuch/0.19+30~g8f95761 (http://notmuchmail.org) Emacs/24.4.1 (x86_64-pc-linux-gnu) Date: Wed, 21 Jan 2015 19:04:45 +0200 Message-ID: <87h9vk5aky.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 12 Jan 2015, Jeremiah Mahler wrote: > Commit 6dda730e55f4 introduced a bug which resulted in inconsistent > brightness levels on different machines. If a suspended was entered > with the screen off some machines would resume with the screen > at minimum brightness and others at maximum brightness. > > The following commands can be used to produce this behavior. > > xset dpms force off > sleep 1 > sudo systemctl suspend > (resume ...) > > The root cause of this problem is a comparison which checks to see if > the backlight level is zero when the panel is enabled. If it is zero, > it is set to the maximum level. Unfortunately, not all machines have a > minimum level of zero. On those machines the level is left at the > minimum instead of begin set to the maximum. > > Fix the bug by updating the comparison to check for the minimum > backlight level instead of zero. Also, expand the comparison for > the possible case when the level is less than the minimum. > > Fixes: 6dda730e55f4 ("respect the VBT minimum backlight brightness") > Signed-off-by: Jeremiah Mahler Pushed to drm-intel-fixes, thanks for the patch. BR, Jani. > --- > > Notes: > Changes in v2: > > - Expand the comparision for the possible case when > the level is less than the minimum. > > drivers/gpu/drm/i915/intel_panel.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c > index 4d63839..dfb783a 100644 > --- a/drivers/gpu/drm/i915/intel_panel.c > +++ b/drivers/gpu/drm/i915/intel_panel.c > @@ -962,7 +962,7 @@ void intel_panel_enable_backlight(struct intel_connector *connector) > > WARN_ON(panel->backlight.max == 0); > > - if (panel->backlight.level == 0) { > + if (panel->backlight.level <= panel->backlight.min) { > panel->backlight.level = panel->backlight.max; > if (panel->backlight.device) > panel->backlight.device->props.brightness = > -- > 2.1.4 > -- Jani Nikula, Intel Open Source Technology Center