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SubjectRe: [PATCH v4 3/9] cpufreq: amd-pstate: change amd-pstate driver to be built-in type
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On 11/10/2022 11:58, Perry Yuan wrote:
> Change the `amd-pstate` driver as the built-in type which can help to
> load the driver before the acpi_cpufreq driver as the default pstate
> driver for the AMD processors.
>
> for the processors do not have the dedicated MSR functions, add
> `amd-pstate=legacy_cppc` to grub which enable shared memory interface
> to communicate with cppc_acpi module to control pstate hints.

Did you sync with Wyes already as I had suggested? Was this the outcome?

I was a bit surprised to see this still as legacy_cppc when reviewing v4.

>
> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
> ---
> drivers/cpufreq/Kconfig.x86 | 2 +-
> drivers/cpufreq/amd-pstate.c | 25 +++++++++++++++----------
> 2 files changed, 16 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/cpufreq/Kconfig.x86 b/drivers/cpufreq/Kconfig.x86
> index 310779b07daf..00476e94db90 100644
> --- a/drivers/cpufreq/Kconfig.x86
> +++ b/drivers/cpufreq/Kconfig.x86
> @@ -35,7 +35,7 @@ config X86_PCC_CPUFREQ
> If in doubt, say N.
>
> config X86_AMD_PSTATE
> - tristate "AMD Processor P-State driver"
> + bool "AMD Processor P-State driver"
> depends on X86 && ACPI
> select ACPI_PROCESSOR
> select ACPI_CPPC_LIB if X86_64
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index ace7d50cf2ac..85a0b3fb56c2 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -59,10 +59,7 @@
> * we disable it by default to go acpi-cpufreq on these processors and add a
> * module parameter to be able to enable it manually for debugging.
> */
> -static bool shared_mem = false;
> -module_param(shared_mem, bool, 0444);
> -MODULE_PARM_DESC(shared_mem,
> - "enable amd-pstate on processors with shared memory solution (false = disabled (default), true = enabled)");
> +static bool shared_mem __read_mostly;
>
> static struct cpufreq_driver amd_pstate_driver;
>
> @@ -653,16 +650,24 @@ static int __init amd_pstate_init(void)
>
> return ret;
> }
> +device_initcall(amd_pstate_init);
>
> -static void __exit amd_pstate_exit(void)
> +static int __init amd_pstate_param(char *str)
> {
> - cpufreq_unregister_driver(&amd_pstate_driver);
> + if (!str)
> + return -EINVAL;
>
> - amd_pstate_enable(false);
> -}
> + /*
> + * support shared memory type CPPC which has no MSR function.
> + * enable amd-pstate on processors with shared memory solution
> + * (amd-pstate=legacy_cppc enabled), it is disabled by default.
> + */
> + if (!strcmp(str, "legacy_cppc"))
> + shared_mem = true;
>
> -module_init(amd_pstate_init);
> -module_exit(amd_pstate_exit);
> + return 0;
> +}
> +early_param("amd-pstate", amd_pstate_param);

Documentation/kernel-parameters.txt needs to be updated for this early
parameter support.

>
> MODULE_AUTHOR("Huang Rui <ray.huang@amd.com>");
> MODULE_DESCRIPTION("AMD Processor P-state Frequency Driver");

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