From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Wilson Subject: Re: [PATCH] drm/i915: do not expose a dysfunctional backlight interface to userspace Date: Mon, 03 Sep 2012 18:51:31 +0100 Message-ID: <051c15$46gcp3@AZSMGA002.ch.intel.com> References: <1346678712-30513-1-git-send-email-jani.nikula@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga14.intel.com (mga14.intel.com [143.182.124.37]) by gabe.freedesktop.org (Postfix) with ESMTP id 79E449F043 for ; Mon, 3 Sep 2012 10:51:59 -0700 (PDT) In-Reply-To: <1346678712-30513-1-git-send-email-jani.nikula@intel.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: intel-gfx@lists.freedesktop.org Cc: jani.nikula@intel.com, david.woodhouse@intel.com List-Id: intel-gfx@lists.freedesktop.org On Mon, 3 Sep 2012 16:25:12 +0300, Jani Nikula wrote: > Previously intel_panel_setup_backlight() would create a sysfs backlight > interface with max brightness of 1 if it was unable to figure out the max > backlight brightness. This rendered the backlight interface useless. > > Do not create a dysfunctional backlight interface to begin with. > > Signed-off-by: Jani Nikula Reviewed-by: Chris Wilson > --- > > See https://bugzilla.redhat.com/show_bug.cgi?id=752595 > > There's still a bug somewhere in the userspace as well; it should always > prefer the platform backlight interface over the raw one. This patch might > have the effect of hiding that particular userspace issue, but we shouldn't > be exporting a backlight interface that's useless no matter what. It was fixed. UXA uses a hardcoded set of preferred platform drivers, SNA looks at all the backlights under /sys/class/backlight and sorts them by type. We still have the issue of multi-panel or just multiple backlight interfaces and choosing the wrong one randomly. libbacklight's idea was to expose some more details through the kernel to be able to link device + connector to a particular backlight interface. However, userspace has the Option "Backlight" for fine tuning. -Chris -- Chris Wilson, Intel Open Source Technology Centre