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

Oleksandr Natalenko
2024-05-08T15:20:52Z

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Hello.

On úterý 7. května 2024 16:41:29, SELČ Mario Limonciello wrote:
> 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.

To me it seems like setting it here kills a possibility to set the mode via the kernel cmdline. Regardless of what will be set in `amd_pstate=`, `CONFIG_X86_AMD_PSTATE_DEFAULT_MODE` will be used instead.

>
> > + 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;
> > }
> >
>
>
>

--
Oleksandr Natalenko (post-factum)

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