From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754313AbaCaAOr (ORCPT ); Sun, 30 Mar 2014 20:14:47 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:36408 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753048AbaC3XZC (ORCPT ); Sun, 30 Mar 2014 19:25:02 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Aaron Lu" , "Hans de Goede" , "Rafael J. Wysocki" Date: Mon, 31 Mar 2014 00:23:35 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 132/200] ACPI / video: Filter the _BCL table for duplicate brightness values In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.56-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Hans de Goede commit bd8ba20597f0cfef3ef65c3fd2aa92ab23d4c8e1 upstream. Some devices have duplicate entries in there brightness levels table, ie on my Dell Latitude E6430 the table looks like this: [ 3.686060] acpi backlight index 0, val 80 [ 3.686095] acpi backlight index 1, val 50 [ 3.686122] acpi backlight index 2, val 5 [ 3.686147] acpi backlight index 3, val 5 [ 3.686172] acpi backlight index 4, val 5 [ 3.686197] acpi backlight index 5, val 5 [ 3.686223] acpi backlight index 6, val 5 [ 3.686248] acpi backlight index 7, val 5 [ 3.686273] acpi backlight index 8, val 6 [ 3.686332] acpi backlight index 9, val 7 [ 3.686356] acpi backlight index 10, val 8 [ 3.686380] acpi backlight index 11, val 9 etc. Notice that brightness values 0-5 are all mapped to 5. This means that if userspace writes any value between 0 and 5 to the brightness sysfs attribute and then reads it, it will always return 0, which is somewhat unexpected. This is a problem for ie gnome-settings-daemon, which uses read-modify-write logic when the users presses the brightness up or down keys. This is done this way to take brightness changes from other sources into account. On this specific laptop what happens once the brightness has been set to 0, is that gsd reads 0, adds 5, writes 5, and on the next brightness up key press again reads 0, so things get stuck at the lowest brightness setting. Filtering out the duplicate table entries, makes any write to brightness read back as the written value as one would expect, fixing this. Signed-off-by: Hans de Goede Reviewed-by: Aaron Lu Signed-off-by: Rafael J. Wysocki Signed-off-by: Ben Hutchings --- drivers/acpi/video.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- a/drivers/acpi/video.c +++ b/drivers/acpi/video.c @@ -646,6 +646,7 @@ acpi_video_init_brightness(struct acpi_v union acpi_object *o; struct acpi_video_device_brightness *br = NULL; int result = -EINVAL; + u32 value; if (!ACPI_SUCCESS(acpi_video_device_lcd_query_levels(device, &obj))) { ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Could not query available " @@ -676,7 +677,12 @@ acpi_video_init_brightness(struct acpi_v printk(KERN_ERR PREFIX "Invalid data\n"); continue; } - br->levels[count] = (u32) o->integer.value; + value = (u32) o->integer.value; + /* Skip duplicate entries */ + if (count > 2 && br->levels[count - 1] == value) + continue; + + br->levels[count] = value; if (br->levels[count] > max_level) max_level = br->levels[count];