path: root/Documentation
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authorLinus Torvalds <torvalds@linux-foundation.org>2009-12-30 16:00:24 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-30 16:00:24 -0800
commit08d869aa8683703c4a60fdc574dd0809f9b073cd (patch)
treef9b875013297130d50a66336899962d15530a07b /Documentation
parent05a625486efc3209ae4d98e253dafa6ce0124385 (diff)
parent1201b2a9bec0413188ada1443ece1a52da6dbff4 (diff)
Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6
* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6: ACPI: introduce kernel parameter acpi_sleep=sci_force_enable ACPI: WMI: Survive BIOS with duplicate GUIDs dell-wmi - fix condition to abort driver loading wmi: check find_guid() return value to prevent oops dell-wmi, hp-wmi, msi-wmi: check wmi_get_event_data() return value ACPI: hp-wmi, msi-wmi: clarify that wmi_install_notify_handler() returns an acpi_status dell-wmi: sys_init_module: 'dell_wmi'->init suspiciously returned 21, it should ACPI video: correct error-handling code ACPI video: no warning message if "acpi_backlight=vendor" is used ACPI: fix ACPI=n allmodconfig build thinkpad-acpi: improve Kconfig help text thinkpad-acpi: update volume subdriver documentation thinkpad-acpi: make volume subdriver optional thinkpad-acpi: don't fail to load the entire module due to ALSA problems thinkpad-acpi: don't take the first ALSA slot by default
Diffstat (limited to 'Documentation')
2 files changed, 54 insertions, 9 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 5ba4d9dff113..736d45602886 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -240,7 +240,7 @@ and is between 256 and 4096 characters. It is defined in the file
acpi_sleep= [HW,ACPI] Sleep options
Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
- old_ordering, s4_nonvs }
+ old_ordering, s4_nonvs, sci_force_enable }
See Documentation/power/video.txt for information on
s3_bios and s3_mode.
s3_beep is for debugging; it makes the PC's speaker beep
@@ -253,6 +253,9 @@ and is between 256 and 4096 characters. It is defined in the file
of _PTS is used by default).
s4_nonvs prevents the kernel from saving/restoring the
ACPI NVS memory during hibernation.
+ sci_force_enable causes the kernel to set SCI_EN directly
+ on resume from S1/S3 (which is against the ACPI spec,
+ but some broken systems don't work without it).
acpi_use_timer_override [HW,ACPI]
Use timer override. For some broken Nvidia NF5 boards
diff --git a/Documentation/laptops/thinkpad-acpi.txt b/Documentation/laptops/thinkpad-acpi.txt
index 169091f75e6d..75afa1229fd7 100644
--- a/Documentation/laptops/thinkpad-acpi.txt
+++ b/Documentation/laptops/thinkpad-acpi.txt
@@ -1092,8 +1092,8 @@ WARNING:
its level up and down at every change.
-Volume control
+Volume control (Console Audio control)
procfs: /proc/acpi/ibm/volume
ALSA: "ThinkPad Console Audio Control", default ID: "ThinkPadEC"
@@ -1110,9 +1110,53 @@ the desktop environment to just provide on-screen-display feedback.
Software volume control should be done only in the main AC97/HDA
-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:
+About the ThinkPad Console Audio control:
+ThinkPads have a built-in amplifier and muting circuit that drives the
+console headphone and speakers. This circuit is after the main AC97
+or HDA mixer in the audio path, and under exclusive control of the
+ThinkPads have three special hotkeys to interact with the console
+audio control: volume up, volume down and mute.
+It is worth noting that the normal way the mute function works (on
+ThinkPads that do not have a "mute LED") is:
+1. Press mute to mute. It will *always* mute, you can press it as
+ many times as you want, and the sound will remain mute.
+2. Press either volume key to unmute the ThinkPad (it will _not_
+ change the volume, it will just unmute).
+This is a very superior design when compared to the cheap software-only
+mute-toggle solution found on normal consumer laptops: you can be
+absolutely sure the ThinkPad will not make noise if you press the mute
+button, no matter the previous state.
+The IBM ThinkPads, and the earlier Lenovo ThinkPads have variable-gain
+amplifiers driving the speakers and headphone output, and the firmware
+also handles volume control for the headphone and speakers on these
+ThinkPads without any help from the operating system (this volume
+control stage exists after the main AC97 or HDA mixer in the audio
+The newer Lenovo models only have firmware mute control, and depend on
+the main HDA mixer to do volume control (which is done by the operating
+system). In this case, the volume keys are filtered out for unmute
+key press (there are some firmware bugs in this area) and delivered as
+normal key presses to the operating system (thinkpad-acpi is not
+The ThinkPad-ACPI volume control:
+The preferred way to interact with the Console Audio control is the
+ALSA interface.
+The legacy procfs interface allows one to read the current state,
+and if volume control is enabled, accepts the following commands:
echo up >/proc/acpi/ibm/volume
echo down >/proc/acpi/ibm/volume
@@ -1121,12 +1165,10 @@ mute/unmute control. The available commands are:
echo 'level <level>' >/proc/acpi/ibm/volume
The <level> number range is 0 to 14 although not all of them may be
-distinct. The unmute the volume after the mute command, use either the
+distinct. To unmute the volume after the mute command, use either the
up or down command (the level command will not unmute the volume), or
the unmute command.
-The current volume level and mute state is shown in the file.
You can use the volume_capabilities parameter to tell the driver
whether your thinkpad has volume control or mute-only control:
volume_capabilities=1 for mixers with mute and volume control,

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