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Message-ID: <aecb3986-aa2e-4725-b08b-473b35ca8221@amd.com>
Date: Tue, 11 Jun 2024 14:35:23 -0500
From: Mario Limonciello <mario.limonciello@....com>
To: Perry Yuan <perry.yuan@....com>, gautham.shenoy@....com
Cc: rafael.j.wysocki@...el.com, viresh.kumar@...aro.org, Ray.Huang@....com,
Borislav.Petkov@....com, Alexander.Deucher@....com, Xinmei.Huang@....com,
Xiaojian.Du@....com, Li.Meng@....com, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 10/10] cpufreq: amd-pstate: automatically load pstate
driver by default
On 6/11/2024 03:52, 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.
>
> Meanwhle, user can add driver mode in command line which will override
> the kernel config default option.
>
> [ 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
This is currently "intended" behavior. There is a comment remaining in
the driver at the moment not part of this patch:
/*
* TODO: We need more time to fine tune processors with shared memory
solution
* with community together.
*
* There are some performance drops on the CPU benchmarks which reports
from
* Suse. We are co-working with them to fine tune the shared memory
solution. So
* 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.
*/
Would you say that the performance drops are worked out on the shared
memory designs?
* If so; this comment should be dropped too in this patch.
* If not; this patch really shouldn't be done as is.
>
> Reported-by: Andrei Amuraritei <andamu@...teo.net>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218705
> Signed-off-by: Perry Yuan <perry.yuan@....com>
> ---
> drivers/cpufreq/amd-pstate.c | 27 ++++++++++++++++++---------
> 1 file changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index fa486dfaa7e8..6e5c398810bf 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -1841,28 +1841,37 @@ 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:
> + /*
> + * get driver mode for loading from command line choice or kernel config
> + * cppc_state will be AMD_PSTATE_UNDEFINED if no command line input
> + * command line choice will override the kconfig option
> + */
> + if (cppc_state == AMD_PSTATE_UNDEFINED) {
> + pr_err("pyuan cppc_state == AMD_PSTATE_UNDEFINED \n");
Looks like a debug line escaped into the patch.
> /* 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)) {
> + amd_pstate_acpi_pm_profile_server()) {
> 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;
> @@ -1883,7 +1892,7 @@ 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;
> }
>
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