Re: [Linaro-acpi] [RFC 2/2] CPPC: Initial support for Collaborative Processor Performance Control

Does it need a hardware change for using CPPC?

+static int cppc_cpufreq_target(struct cpufreq_policy *policy,

• unsigned int target_freq,
  

• unsigned int relation)
  

+{

• unsigned int cpu = policy->cpu;
• struct cpc_desc *current_cpu_cpc = per_cpu(cpc_desc, cpu);
• struct cpufreq_freqs freqs;
• u16 status;
• freqs.old = policy->cur;
• freqs.new = target_freq;
• cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
• /* Set CPU Perf thresholds and current desired perf value. */
• acpi_write(policy->max, &current_cpu_cpc->pcc_regs[MAX_PERF]);
• acpi_write(policy->min, &current_cpu_cpc->pcc_regs[MIN_PERF]);
• acpi_write(target_freq, &current_cpu_cpc->pcc_regs[DESIRED_PERF]);
• status = send_pcc_cmd(CMD_WRITE, 0, PCC_SUBSPACE_IDX,

comm_base_addr);

• if (status & CMD_COMPLETE) {

• pr_debug("Failed to set target CPU perf for CPU:%d,
  

status:%d\n",

• 		cpu, status);
  

• return -EINVAL;
  

• }
• return 0;

+}

-> Don't need cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE)?

• /* Base address returned from PCC subspace desc needs to ioremap'd.

• * Used by the client to send/recv data from platform.
  

• */
  

• comm_base_addr = ioremap_nocache(pcc_comm_base_addr, len);
• if (comm_base_addr) {

->Should be if (!comm_base_addr) ?

• pr_err("Could not map PCC communicate channel\n");
  

• ret = -ENOMEM;
  

• goto out_err;
  

• }

Thanks Best Regards.