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authorAlexander Schremmer <alex@alexanderweb.de>2019-08-22 13:48:33 +0200
committerAndy Shevchenko <andriy.shevchenko@linux.intel.com>2019-09-07 21:16:09 +0300
commit110ea1d833ad291272d52e0a40a06157a3d9ba17 (patch)
tree3acdf105f4d3b4d0b076092f3028f130d8cd3042 /Documentation/admin-guide
parentad0d315b4d4e7138f43acf03308192ec00e9614d (diff)
platform/x86: thinkpad_acpi: Add ThinkPad PrivacyGuard
This feature is found optionally in T480s, T490, T490s. The feature is called lcdshadow and visible via /proc/acpi/ibm/lcdshadow. The ACPI methods \_SB.PCI0.LPCB.EC.HKEY.{GSSS,SSSS,TSSS,CSSS} are available in these machines. They get, set, toggle or change the state apparently. The patch was tested on a 5.0 series kernel on a T480s. Signed-off-by: Alexander Schremmer <alex@alexanderweb.de> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Diffstat (limited to 'Documentation/admin-guide')
-rw-r--r--Documentation/admin-guide/laptops/thinkpad-acpi.rst23
1 files changed, 23 insertions, 0 deletions
diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
index adea0bf2acc5..822907dcc845 100644
--- a/Documentation/admin-guide/laptops/thinkpad-acpi.rst
+++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
@@ -49,6 +49,7 @@ detailed description):
- Fan control and monitoring: fan speed, fan enable/disable
- WAN enable and disable
- UWB enable and disable
+ - LCD Shadow (PrivacyGuard) enable and disable
A compatibility table by model and feature is maintained on the web
site, http://ibm-acpi.sf.net/. I appreciate any success or failure
@@ -1409,6 +1410,28 @@ Sysfs notes
Documentation/driver-api/rfkill.rst for details.
+LCD Shadow control
+------------------
+
+procfs: /proc/acpi/ibm/lcdshadow
+
+Some newer T480s and T490s ThinkPads provide a feature called
+PrivacyGuard. By turning this feature on, the usable vertical and
+horizontal viewing angles of the LCD can be limited (as if some privacy
+screen was applied manually in front of the display).
+
+procfs notes
+^^^^^^^^^^^^
+
+The available commands are::
+
+ echo '0' >/proc/acpi/ibm/lcdshadow
+ echo '1' >/proc/acpi/ibm/lcdshadow
+
+The first command ensures the best viewing angle and the latter one turns
+on the feature, restricting the viewing angles.
+
+
EXPERIMENTAL: UWB
-----------------