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path: root/arch/ia64/kernel/cpufreq/acpi-cpufreq.c
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2005-12-01[ACPI] Avoid BIOS inflicted crashes by evaluating _PDC only onceVenkatesh Pallipadi
Linux invokes the AML _PDC method (Processor Driver Capabilities) to tell the BIOS what features it can handle. While the ACPI spec says nothing about the OS invoking _PDC multiple times, doing so with changing bits seems to hopelessly confuse the BIOS on multiple platforms up to and including crashing the system. Factor out the _PDC invocation so Linux invokes it only once. http://bugzilla.kernel.org/show_bug.cgi?id=5483 Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Len Brown <len.brown@intel.com>
2005-08-26[IA64] Add ACPI based P-state supportVenkatesh Pallipadi
Patch to support P-state transitions on ia64. This driver is based on ACPI, and uses the ACPI processor driver interface to find out the P-state support information for the processor. This driver plugs into generic cpufreq infrastructure. Once this driver is loaded successfully, ondemand/userspace governor can be used to change the CPU frequency dynamically based on load or on request from userspace process. Refer : ACPI specification - http://www.acpi.info P-state related PAL calls - http://developer.intel.com/design/itanium/downloads/24869909.pdf Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Tony Luck <tony.luck@intel.com>