path: root/Documentation
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authorZhao Yakui <yakui.zhao@intel.com>2008-08-11 14:57:50 +0800
committerLen Brown <len.brown@intel.com>2008-10-22 17:59:57 -0400
commitf5adfaa372c76423b6e8e4727a9701330374f364 (patch)
treeb7783111c8f027d954506d7440d806817de13f6b /Documentation
parenteab4b645769fa2f8703f5a3cb0cc4ac090d347af (diff)
ACPI: Add "acpi.power_nocheck=1" to disable power state check in power transition
Maybe the incorrect power state is returned on the bogus bios, which is different with the real power state. For example: the bios returns D0 state and the real power state is D3. OS expects to set the device to D0 state. In such case if OS uses the power state returned by the BIOS and checks the device power state very strictly in power transition, the device can't be transited to the correct power state. So the boot option of "acpi.power_nocheck=1" is added to avoid checking the device power in the course of device power transition. http://bugzilla.kernel.org/show_bug.cgi?id=8049 http://bugzilla.kernel.org/show_bug.cgi?id=11000 Signed-off-by: Zhao Yakui <yakui.zhao@intel.com> Signed-off-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Li Shaohua <shaohua.li@intel.com> Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'Documentation')
1 files changed, 8 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 44d1bd142ed..99cf83fd694 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -251,6 +251,14 @@ and is between 256 and 4096 characters. It is defined in the file
Warning: Many of these options can produce a lot of
output and make your system unusable. Be very careful.
+ acpi.power_nocheck= [HW,ACPI]
+ Format: 1/0 enable/disable the check of power state.
+ On some bogus BIOS the _PSC object/_STA object of
+ power resource can't return the correct device power
+ state. In such case it is unneccessary to check its
+ power state again in power transition.
+ 1 : disable the power state check
acpi_pm_good [X86-32,X86-64]
Override the pmtimer bug detection: force the kernel
to assume that this machine's pmtimer latches its value