Re: [PATCH v4 10/11] cpufreq: amd-pstate: auto-load pstate driver by default

Mario Limonciello
2024-06-18T19:25:29Z

On 6/17/2024 01:59, Perry Yuan wrote:
> If the `amd-pstate` driver is not loaded automatically by default,
> it is because the kernel command line parameter has not been added.
> To resolve this issue, it is necessary to call the `amd_pstate_set_driver()`
> function to enable the desired mode (passive/active/guided) before registering
> the driver instance.
>
> This ensures that the driver is loaded correctly without relying on the kernel
> command line parameter.
>
> When there is no parameter added to command line, Kernel config will
> provide the default mode to load.
>
> Meanwhle, user can add driver mode in command line which will override

Meanwhile

> the kernel config default option.

I think you'll probably want to swap the order of patch 10 and patch 11.

>
> Reported-by: Andrei Amuraritei <andamu@posteo.net>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218705
> Signed-off-by: Perry Yuan <perry.yuan@amd.com>

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

> ---
> drivers/cpufreq/amd-pstate.c | 24 +++++++++++++++++-------
> 1 file changed, 17 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index cf68343219d1..b48fd60cbc6d 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -1857,8 +1857,13 @@ static int __init amd_pstate_init(void)
> /* check if this machine need CPPC quirks */
> dmi_check_system(amd_pstate_quirks_table);
>
> - switch (cppc_state) {
> - case AMD_PSTATE_UNDEFINED:
> + /*
> + * determine the driver mode from the command line or kernel config.
> + * If no command line input is provided, cppc_state will be AMD_PSTATE_UNDEFINED.
> + * command line options will override the kernel config settings.
> + */
> +
> + if (cppc_state == AMD_PSTATE_UNDEFINED) {
> /* Disable on the following configs by default:
> * 1. Undefined platforms
> * 2. Server platforms
> @@ -1870,15 +1875,20 @@ static int __init amd_pstate_init(void)
> pr_info("driver load is disabled, boot with specific mode to enable this\n");
> return -ENODEV;
> }
> - ret = amd_pstate_set_driver(CONFIG_X86_AMD_PSTATE_DEFAULT_MODE);
> - if (ret)
> - return ret;
> - break;
> + /* get driver mode from kernel config option [1:4] */
> + cppc_state = CONFIG_X86_AMD_PSTATE_DEFAULT_MODE;
> + }
> +
> + switch (cppc_state) {
> case AMD_PSTATE_DISABLE:
> + pr_info("driver load is disabled, boot with specific mode to enable this\n");
> return -ENODEV;
> case AMD_PSTATE_PASSIVE:
> case AMD_PSTATE_ACTIVE:
> case AMD_PSTATE_GUIDED:
> + ret = amd_pstate_set_driver(cppc_state);
> + if (ret)
> + return ret;
> break;
> default:
> return -EINVAL;
> @@ -1899,7 +1909,7 @@ static int __init amd_pstate_init(void)
> /* enable amd pstate feature */
> ret = amd_pstate_enable(true);
> if (ret) {
> - pr_err("failed to enable with return %d\n", ret);
> + pr_err("failed to enable driver mode(%d)\n", cppc_state);
> return ret;
> }
>