Re: [PATCH 11/11] cpufreq: amd-pstate: automatically load pstate driver by default

Mario Limonciello
2024-05-07T14:41:36Z

On 5/7/2024 02:15, 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.
>
> [ 0.917789] usb usb6: Manufacturer: Linux 6.9.0-rc6-amd-pstate-new-fix-v1 xhci-hcd
> [ 0.982579] amd_pstate: failed to register with return -22
>
> 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>
> ---
> drivers/cpufreq/amd-pstate.c | 39 +++++++++++++++++++-----------------
> 1 file changed, 21 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 3ff381c4edf7..f5368497ee79 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -66,7 +66,7 @@
> static struct cpufreq_driver *current_pstate_driver;
> static struct cpufreq_driver amd_pstate_driver;
> static struct cpufreq_driver amd_pstate_epp_driver;
> -static int cppc_state = AMD_PSTATE_UNDEFINED;
> +static int cppc_state;
> static bool cppc_enabled;
> static bool amd_pstate_prefcore = true;
> static struct quirk_entry *quirks;
> @@ -1762,6 +1762,16 @@ static int __init amd_pstate_init(void)
> if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
> return -ENODEV;
>
> + /* Disable on the following configs by default:
> + * 1. Undefined platforms
> + * 2. Server platforms
> + */
> + if (amd_pstate_acpi_pm_profile_undefined() ||
> + amd_pstate_acpi_pm_profile_server()) {
> + pr_info("driver load is disabled for server or undefined platform\n");
> + return -ENODEV;
> + }
> +
> /* show debug message only if CPPC is not supported */
> if (!amd_cppc_supported())
> return -EOPNOTSUPP;
> @@ -1781,28 +1791,21 @@ static int __init amd_pstate_init(void)
> /* check if this machine need CPPC quirks */
> dmi_check_system(amd_pstate_quirks_table);
>
> + /* get default driver mode for loading*/
> + cppc_state = CONFIG_X86_AMD_PSTATE_DEFAULT_MODE;

Rather than setting it here within amd_pstate_init() I think you can
just set it at line 67 to CONFIG_X86_AMD_PSTATE_DEFAULT_MODE.

> + pr_debug("cppc working state set to mode:%d\n", cppc_state);

I think this debug line is going to be unnecessary when it's already
hardcoded to kernel config.

> +
> switch (cppc_state) {
> - case AMD_PSTATE_UNDEFINED:
> - /* Disable on the following configs by default:
> - * 1. Undefined platforms
> - * 2. Server platforms
> - * 3. Shared memory designs
> - */
> - if (amd_pstate_acpi_pm_profile_undefined() ||
> - amd_pstate_acpi_pm_profile_server() ||
> - !cpu_feature_enabled(X86_FEATURE_CPPC)) {
> - 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;
> case AMD_PSTATE_DISABLE:
> + pr_info("driver load is disabled, boot with specific mode to enable this\n");
> return -ENODEV;
> + case AMD_PSTATE_UNDEFINED:

With the intent of this patch I no longer see a need for
AMD_PSTATE_UNDEFINED in the rest of the driver (or in this case
statement even).

I feel you can drop it from amd-pstate.h.

> 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;
> @@ -1823,7 +1826,7 @@ 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) with return %d\n", cppc_state, ret);
> return ret;
> }
>