Lines Matching refs:PCC
2 * pcc-cpufreq.txt - PCC interface documentation
33 1.1 PCC interface
46 Processor Clocking Control (PCC) is an interface between the platform
50 The PCC driver (pcc-cpufreq) allows OSPM to take advantage of the PCC
53 OS utilizes the PCC interface to inform platform firmware what frequency the
59 1.1 PCC interface:
61 The complete PCC specification is available here:
64 PCC relies on a shared memory region that provides a channel for communication
65 between the OS and platform firmware. PCC also implements a "doorbell" that
69 The ACPI PCCH() method is used to discover the location of the PCC shared
74 The following commands are supported by the PCC interface:
82 When PCC mode is enabled, the platform will not expose processor performance
89 The PCC driver fills in the command interface, and the input buffer and
93 Each PCC command is "global" in scope and can affect all the logical CPUs in
94 the system. Therefore, PCC is capable of performing "group" updates. With PCC
115 The PCC driver will load on any system where the platform firmware:
116 * supports the PCC interface, and the associated PCCH() and PCCP() methods
120 Currently, certain HP ProLiant platforms implement the PCC interface. On those
121 platforms PCC is the "default" choice.
124 such an instance, as is also the case on platforms where the PCC interface
125 is not implemented, the PCC driver will fail to load silently.
132 The PCC driver loads with a message such as:
147 |-- this is the version of the PCC specification the driver adheres to
151 /sys filesystem and how their values are affected by the PCC driver:
162 The cpuinfo_transition_latency field is 0. The PCC specification does
199 Currently, the PCC driver does not evaluate _PSD. The platforms that support
200 PCC do not implement SW_ALL. So OSPM doesn't need to perform any coordination
206 expected to work with the PCC driver. Since the "cpufreq_stats" module
207 provides information wrt each P-state, it is not applicable to the PCC driver.