On 27.05.2025 10:48, Penny Zheng wrote:
> @@ -537,6 +537,14 @@ choice of `dom0-kernel` is deprecated and not supported
> by all Dom0 kernels.
> * `amd-cppc` selects ACPI Collaborative Performance and Power Control (CPPC)
> on supported AMD hardware to provide finer grained frequency control
> mechanism. The default is disabled.
> +* `active` is a boolean to enable amd-cppc driver in active(autonomous) mode.
> + In this mode, users could write to energy performance preference
> + register(epp) to tell hardware if they want to bias toward performance or
> + energy efficiency.
Who or what is "users" here? Certainly not the person reading the doc, trying
to determine whether to use this command line sub-option. That person can't
write to the EPP register. (Or really they maybe can, but they shouldn't.)
It's the driver which is supposed to be carrying out such writes, isn't it?
> +static int cf_check amd_cppc_epp_set_policy(struct cpufreq_policy *policy)
> +{
> + const struct amd_cppc_drv_data *data = per_cpu(amd_cppc_drv_data,
> + policy->cpu);
> + uint8_t max_perf, min_perf, epp;
> +
> + /*
> + * min_perf represents the idle frequency, while max_perf represents
> + * the maximum frequency
> + */
> + max_perf = data->caps.highest_perf;
> + min_perf = data->caps.lowest_perf;
> +
> + /*
> + * We set min_perf with highest_perf in performance mode
> + * and max_perf with lowest_perf in powersave mode, to achieve
> + * ultmost performance and power savings.
> + */
> + switch ( policy->policy )
> + {
> + case CPUFREQ_POLICY_PERFORMANCE:
> + /* Force the epp value to be zero for performance policy */
> + epp = CPPC_ENERGY_PERF_MAX_PERFORMANCE;
> + min_perf = data->caps.highest_perf;
> + break;
> + case CPUFREQ_POLICY_POWERSAVE:
> + /* Force the epp value to be 0xff for powersave policy */
> + epp = CPPC_ENERGY_PERF_MAX_POWERSAVE;
> + max_perf = data->caps.lowest_perf;
> + break;
> + default:
> + epp = per_cpu(epp_init, policy->cpu);
> + break;
> + }
Blank lines please between non-fall-through case blocks.
Jan
