From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: brightness control on thinkpad t61p Date: Sun, 23 Dec 2007 00:00:57 -0800 Message-ID: <20071223000057.739d5891.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from smtp2.linux-foundation.org ([207.189.120.14]:51892 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750872AbXLWIBw (ORCPT ); Sun, 23 Dec 2007 03:01:52 -0500 Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: linux-acpi@vger.kernel.org, Henrique de Moraes Holschuh Cc: "Rafael J. Wysocki" When I fire up the latest Linus tree on my thinkpad t61p I get: thinkpad_acpi: ThinkPad ACPI Extras v0.17 thinkpad_acpi: http://ibm-acpi.sf.net/ thinkpad_acpi: ThinkPad BIOS 7LET44WW (1.14 ), EC 7KHT22WW-1.06 thinkpad_acpi: Lenovo ThinkPad T61p thinkpad_acpi: radio switch found; radios are enabled ACPI: Lid Switch [LID] input: Sleep Button (CM) as /class/input/input6 ACPI: Sleep Button (CM) [SLPB] thinkpad_acpi: standard ACPI backlight interface available, not loading native one... and /sys/class/backlight/thinkpad_screen/brightness is no longer present, so my `brightness' script no longer works. That, my friends, is a regression. Here's my script: ( 0 sh -c "echo $1 > /proc/acpi/sony/brightness" 0 sh -c "echo $1 > /proc/acpi/sony/brightness_default" 0 sh -c "echo $1 > /sys/class/backlight/sony/brightness" 0 sh -c "echo $1 > /sys/class/backlight/thinkpad_screen/brightness" ) 2>/dev/null which rather shows how pathetic we are in this area. Ho hum. So I go hunting around and find /sys/class/backlight/acpi_video0/ and /sys/class/backlight/acpi_video1/ Why are there two of them? Both of these have a `brightness' entry which has contents of 100. When I set that to 10, the screen's brightness is not reduced. So as far as I can tell, we have lost the ability to alter the brightness of the screen on this machine.