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Clark" , platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org, Anghel Mihai-Alexandru Subject: [PATCH] Documentation: thinkpad-acpi: fix backlight power attribute name Date: Sun, 15 Nov 2026 14:46:42 +0200 Message-ID: <20261115124642.983197-1-mih@ianghel.com> X-Mailer: git-send-email 2.54.0 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The sysfs notes called the thinkpad_screen attribute "power". The generic backlight class names it "bl_power", so the docs now use that name and describe its values (0 on, 4 off). The intro now points to the backlight class documentation instead of saying it is poorly documented. AI-assisted: Claude Sonnet 5.5 and Claude Haiku 5.5. Signed-off-by: Anghel Mihai-Alexandru --- .../admin-guide/laptops/thinkpad-acpi.rst | 29 ++++++++++++------- 1 file changed, 18 insertions(+), 11 deletions(-) diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst b/Documentation/admin-guide/laptops/thinkpad-acpi.rst index db4588af0278..f6377fad3aa0 100644 --- a/Documentation/admin-guide/laptops/thinkpad-acpi.rst +++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst @@ -1066,8 +1066,9 @@ The available commands are:: Sysfs notes ^^^^^^^^^^^ -The interface is implemented through the backlight sysfs class, which is -poorly documented at this time. +The interface is implemented through the backlight sysfs class. See +Documentation/gpu/backlight.rst and +Documentation/ABI/stable/sysfs-class-backlight for details. Locate the thinkpad_screen device under /sys/class/backlight, and inside it there will be the following attributes: @@ -1082,17 +1083,23 @@ it there will be the following attributes: brightness: Writes request the driver to change brightness to the given value. Reads will tell you what brightness the - driver is trying to set the display to when "power" is set - to zero and the display has not been dimmed by a kernel + driver is trying to set the display to when "bl_power" is + zero and the display has not been dimmed by a kernel power management event. - power: - power management mode, where 0 is "display on", and 1 to 3 - will dim the display backlight to brightness level 0 - because thinkpad-acpi cannot really turn the backlight - off. Kernel power management events can temporarily - increase the current power management level, i.e. they can - dim the display. + bl_power: + Backlight power management mode, provided by the generic + backlight class. 0 (BACKLIGHT_POWER_ON) turns the display + on, and 4 (BACKLIGHT_POWER_OFF) powers the display down; + the driver decides how to blank the output. 1 + (BACKLIGHT_POWER_REDUCED) is deprecated. Any other + non-zero value is also treated as blank. Kernel power + management events can temporarily blank the display. + + thinkpad-acpi gets its brightness from + backlight_get_brightness(), which yields zero while the + display is blank, so the backlight level is set to zero + in that case. WARNING: -- 2.54.0