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Diffstat (limited to 'Documentation/laptops/thinkpad-acpi.txt')
| -rw-r--r-- | Documentation/laptops/thinkpad-acpi.txt | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/laptops/thinkpad-acpi.txt b/Documentation/laptops/thinkpad-acpi.txt index bd87682103c1..6a5814330e51 100644 --- a/Documentation/laptops/thinkpad-acpi.txt +++ b/Documentation/laptops/thinkpad-acpi.txt @@ -1097,6 +1097,18 @@ Volume control procfs: /proc/acpi/ibm/volume +NOTE: by default, the volume control interface operates in read-only +mode, as it is supposed to be used for on-screen-display purposes. +The read/write mode can be enabled through the use of the +"volume_control=1" module parameter. + +NOTE: distros are urged to not enable volume_control by default, this +should be done by the local admin only. The ThinkPad UI is for the +console audio control to be done through the volume keys only, and for +the desktop environment to just provide on-screen-display feedback. +Software volume control should be done only in the main AC97/HDA +mixer. + This feature allows volume control on ThinkPad models with a digital volume knob (when available, not all models have it), as well as mute/unmute control. The available commands are: @@ -1465,3 +1477,4 @@ Sysfs interface changelog: 0x020600: Marker for backlight change event support. 0x020700: Support for mute-only mixers. + Volume control in read-only mode by default. |