Re: [PATCH v9 05/13] cpufreq: amd-pstate: optimize driver working mode selection in amd_pstate_param()

Limonciello, Mario
2023-01-04T00:34:01Z

On 12/25/2022 10:34, Perry Yuan wrote:
> From: Wyes Karny <wyes.karny@amd.com>
>
> The amd-pstate driver may support multiple working modes.
> Introduce a variable to keep track of which mode is currently enabled.
> Here we use cppc_state var to indicate which mode is enabled.
> This change will help to simplify the the amd_pstate_param() to choose
> which mode used for the following driver registration.
>
> Signed-off-by: Perry Yuan <perry.yuan@amd.com>
> Signed-off-by: Wyes Karny <wyes.karny@amd.com>

Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>

> ---
> drivers/cpufreq/amd-pstate.c | 39 +++++++++++++++++++++++++++---------
> include/linux/amd-pstate.h | 17 ++++++++++++++++
> 2 files changed, 46 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index c17bd845f5fc..65c16edbbb20 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -60,7 +60,18 @@
> * module parameter to be able to enable it manually for debugging.
> */
> static struct cpufreq_driver amd_pstate_driver;
> -static int cppc_load __initdata;
> +static int cppc_state = AMD_PSTATE_DISABLE;
> +
> +static inline int get_mode_idx_from_str(const char *str, size_t size)
> +{
> + int i;
> +
> + for (i=0; i < AMD_PSTATE_MAX; i++) {
> + if (!strncmp(str, amd_pstate_mode_string[i], size))
> + return i;
> + }
> + return -EINVAL;
> +}
>
> static inline int pstate_enable(bool enable)
> {
> @@ -626,10 +637,10 @@ static int __init amd_pstate_init(void)
> /*
> * by default the pstate driver is disabled to load
> * enable the amd_pstate passive mode driver explicitly
> - * with amd_pstate=passive in kernel command line
> + * with amd_pstate=passive or other modes in kernel command line
> */
> - if (!cppc_load) {
> - pr_debug("driver load is disabled, boot with amd_pstate=passive to enable this\n");
> + if (cppc_state == AMD_PSTATE_DISABLE) {
> + pr_debug("driver load is disabled, boot with specific mode to enable this\n");
> return -ENODEV;
> }
>
> @@ -671,16 +682,24 @@ device_initcall(amd_pstate_init);
>
> static int __init amd_pstate_param(char *str)
> {
> + size_t size;
> + int mode_idx;
> +
> if (!str)
> return -EINVAL;
>
> - if (!strcmp(str, "disable")) {
> - cppc_load = 0;
> - pr_info("driver is explicitly disabled\n");
> - } else if (!strcmp(str, "passive"))
> - cppc_load = 1;
> + size = strlen(str);
> + mode_idx = get_mode_idx_from_str(str, size);
>
> - return 0;
> + if (mode_idx >= AMD_PSTATE_DISABLE && mode_idx < AMD_PSTATE_MAX) {
> + cppc_state = mode_idx;
> + if (cppc_state == AMD_PSTATE_DISABLE)
> + pr_info("driver is explicitly disabled\n");
> +
> + return 0;
> + }
> +
> + return -EINVAL;
> }
> early_param("amd_pstate", amd_pstate_param);
>
> diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
> index 1c4b8659f171..dae2ce0f6735 100644
> --- a/include/linux/amd-pstate.h
> +++ b/include/linux/amd-pstate.h
> @@ -74,4 +74,21 @@ struct amd_cpudata {
> bool boost_supported;
> };
>
> +/*
> + * enum amd_pstate_mode - driver working mode of amd pstate
> + */
> +enum amd_pstate_mode {
> + AMD_PSTATE_DISABLE = 0,
> + AMD_PSTATE_PASSIVE,
> + AMD_PSTATE_ACTIVE,
> + AMD_PSTATE_MAX,
> +};
> +
> +static const char * const amd_pstate_mode_string[] = {
> + [AMD_PSTATE_DISABLE] = "disable",
> + [AMD_PSTATE_PASSIVE] = "passive",
> + [AMD_PSTATE_ACTIVE] = "active",
> + NULL,
> +};
> +
> #endif /* _LINUX_AMD_PSTATE_H */