From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Wilson Subject: Re: [PATCH] xf86-video-intel: change order of DPMS operations Date: Thu, 08 Dec 2011 16:37:55 +0000 Message-ID: References: <1323303641-13277-1-git-send-email-sque@chromium.org> <86sjkv2f9b.fsf@sumi.keithp.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by gabe.freedesktop.org (Postfix) with ESMTP id 33BC09E7F8 for ; Thu, 8 Dec 2011 08:38:18 -0800 (PST) In-Reply-To: <86sjkv2f9b.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 , jbarnes@virtuousgeek.org, intel-gfx@lists.freedesktop.org, eric@anholt.net Cc: Simon Que , bleung@chromium.org List-Id: intel-gfx@lists.freedesktop.org On Thu, 08 Dec 2011 08:35:12 -0800, Keith Packard wrote: > On Thu, 08 Dec 2011 14:10:06 +0000, Chris Wilson wrote: > > > I had to remind myself why both the driver and the kernel are both > > touching the backlight across DPMS; the answer as I see it is that the > > kernel only knows about the raw backlight interface whereas the driver > > adjusts it via the preferred interface (which should handle the cases > > where the backlight modulation is handled independently of the PWM > > registers). > > Something in the kernel should be managing the backlight or we won't be > doing this right when fbdev is running. User space should not have to > know about the vagaries of the kernel backlight land. The tricky part is figuring out the right interface to use. Matthew was working upon such a mechanism to provide userspace with the ability to actually find the backlight controller for a respective output, but I don't believe there was ever a kernel API for i915 to call. -Chris -- Chris Wilson, Intel Open Source Technology Centre