From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751185Ab2AUScO (ORCPT ); Sat, 21 Jan 2012 13:32:14 -0500 Received: from home.keithp.com ([63.227.221.253]:39317 "EHLO keithp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751043Ab2AUScN (ORCPT ); Sat, 21 Jan 2012 13:32:13 -0500 From: Keith Packard To: Chris Diamand , linux-kernel@vger.kernel.org Cc: tiwai@suse.de, melchior.franz@gmail.com Subject: Re: i915/kms/backlight-combo mode problem (was: Re: Linux 2.6.39-rc5) In-Reply-To: <4F1AF145.2090407@gmail.com> References: <4F1AF145.2090407@gmail.com> User-Agent: Notmuch/0.11 (http://notmuchmail.org) Emacs/23.3.1 (i486-pc-linux-gnu) Date: Sat, 21 Jan 2012 10:32:09 -0800 Message-ID: <86k44kkity.fsf@sumi.keithp.com> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Transfer-Encoding: quoted-printable On Sat, 21 Jan 2012 17:09:25 +0000, Chris Diamand = wrote: > Hi, >=20 > I have the problem described in the thread here=20 > (https://lkml.org/lkml/2011/4/29/217) where the backlight > values are reversed so although stuff is displayed on the screen, the=20 > backlight is off. This occurs with kernels from about 2.6.39 onwards. >=20 > After booting a "broken" kernel (>~2.6.39), the backlight can be lit=20 > temporarily with: > setpci -s 00:02.0 F4.B=3D0 > and then turned off with: > setpci -s 00:02.0 F4.B=3DFF Can you experiment with other values? I'd like to know if it's completely reversed, or if there's some other interaction here. Testing 0x80, 0x7f, 0x01, 0xfe would all be interesting to me. I suspect that writes to the LPBC value are being trapped by SMI and 'doing things' underneath. > Yesterday I tried this patch, https://lkml.org/lkml/2011/4/30/37 by=20 > manually applying it to the 3.2.1 > kernel source - this fixes the problem. Can you still turn the backlight off with this patch in place? > ** Unfortunately the LKML thread stops after this patch and given that=20 > the problem is still present in the latest source, this code wasn't=20 > pushed into the kernel. Is there a reason for this or was it just=20 > forgotten about? What can I do about this? I am happy to make a git=20 > patch with the latest source if this will help. The patch would completely bypass LPBC-based brightness controls if the backlight happened to be off when the driver started, which isn't exactly what you want. =2D-=20 keith.packard@intel.com --=-=-= Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIVAwUBTxsEqTYtFsjWk68qAQhHPA//StQgVhot3xfgkQUTqQn8ASjZ4Xjdwx4B MbIb7A/oE5ZFSrUTYiGE33YPODxwU81Prj38HENujFMpqeZiMeLmn5zm8zNVfPqV XO00gD/me1rILG4raneQnHuVTR9C/UqB2PzlZGzatIOYHtMRjvCqTTyI+fAGJzMF bRwLS6YjYvVE11PvRb2a3Ned3LihJ2nOkNkh6/xUCACaMrtDqNNOT5wI2wTc8xIQ G8zKC9vZcVHRgHalBQgea+BOv0k31zBcOlvx3+jzkOxWcXml6LltidMWA791s8zP NcHr/rZUgZ0fB8+tt4rd/2d370U+7d+F+BI+QJP9dPk3iXOuzXQaizNrhyB8RIHJ 2gEgSWlWUtXh7+yCTm8m1uAlRkV9CxrDWVMg101NjZplYnxBGXT96gISU2/Jg/Bm tTQX+AGlrPcOhQiHAEi/97NLNv0c226UpoJrq9QTsKKRVFnIAhD8vVG1aFY42s52 6kBn1qz1EI8wvpxiU8kkq3YHS6f2B8rrt7Xkv0r8srlrzWiPjQVGjCxEFllxaOZ6 hQZDm6tY/r8HrHriVZSAvjAlq/sRSXUdQIpOII1+e8dGdzbLKYH0yZzCng/JhGqh VafpXizh8MJetqX302cD54Ls+vmrQh7uj0dMFGdvkdnHJ8PytAlhX9xH2vuJA71m +vGD+cij0pg= =Ev+E -----END PGP SIGNATURE----- --=-=-=--