From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrey Borzenkov Subject: rc6+ regression - backlight reset to 0 on boot after 7c0ea45be4f114d85ee35caeead8e1660699c46f Date: Wed, 2 Apr 2008 22:53:15 +0400 Message-ID: <200804022253.17862.arvidjaar@mail.ru> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart2019604.mx0Q6UFNd7"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Return-path: Received: from mx6.mail.ru ([194.67.23.26]:20381 "EHLO mx6.mail.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756966AbYDBSxZ (ORCPT ); Wed, 2 Apr 2008 14:53:25 -0400 Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Rafael J. Wysocki" , Zhao Yakui Cc: linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org --nextPart2019604.mx0Q6UFNd7 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Commit 7c0ea45be4f114d85ee35caeead8e1660699c46f registers ACPI backlight even if _BQC method (query current backlight level) is missing. The effect is: during initialization video.c:acpi_video_device_find_cap() calls backlight_update_status(). It tries to fetch actual level via acpi_video_get_brightness() - but as _BQC is missing it just returns current value as stored in memory - i.e. zero, because it was never set. So effectively backlight_update_status() reset brightness to minimal value == 0. This happens on Toshiba Portege 4000. Verified by reverting commit on top of rc8. On a side note, it would be nice to fit backlight device into actual ACPI device tree instead of /devices/virtual. --nextPart2019604.mx0Q6UFNd7 Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEABECAAYFAkfz1h0ACgkQR6LMutpd94yg0wCgsofIQqOpo7kjJsw7D/SdgjIu p7kAoISGT98GrGTc+d/qoYFZ4XnjH5Jh =BwDj -----END PGP SIGNATURE----- --nextPart2019604.mx0Q6UFNd7--