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@xxxxxxxxxx>
> Reviewed-by: Al Stone <al.stone@xxxxxxxxxx>
> ---
[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
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