On Wednesday, September 09, 2015 04:27:04 PM Ashwin Chaugule wrote:
CPPC stands for Collaborative Processor Performance Controls and is defined in the ACPI v5.0+ spec. It describes CPU performance controls on an abstract and continuous scale allowing the platform (e.g. remote power processor) to flexibly optimize CPU performance with its knowledge of power budgets and other architecture specific knowledge.
This patch adds a shim which exports commonly used functions to get and set CPPC specific controls for each CPU. This enables CPUFreq drivers to gather per CPU performance data and use with exisiting governors or even allows for customized governors which are implemented inside CPUFreq drivers.
Signed-off-by: Ashwin Chaugule ashwin.chaugule@linaro.org Reviewed-by: Al Stone al.stone@linaro.org
[cut]
+/**
- acpi_get_psd_map - Map the CPUs in a common freq domain as indicated
- in the respective _PSD entries.
One minor nit: this needs to be one-line in a proper kerneldoc.
- @all_cpu_data: This array of pointers contains all the CPU specific
- details to access CPPC registers and freq domain information for each
- CPU.
Ditto.
You can add more description below.
[cut]
+int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs) +{
- struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
- struct cpc_register_resource *delivered_reg, *reference_reg;
- u64 delivered, reference;
- int ret = 0;
- if (!cpc_desc) {
pr_debug("No CPC descriptor for CPU:%d\n", cpunum);return -ENODEV;- }
- delivered_reg = &cpc_desc->cpc_regs[DELIVERED_CTR];
- reference_reg = &cpc_desc->cpc_regs[REFERENCE_CTR];
- spin_lock(&pcc_lock);
I still have the question about this lock.
Why does it have to be a spinlock?
Rafael