From: Mario Limonciello <mario.limonciello@amd.com>
To: Perry Yuan <perry.yuan@amd.com>,
rafael.j.wysocki@intel.com, viresh.kumar@linaro.org,
Ray.Huang@amd.com, gautham.shenoy@amd.com,
Borislav.Petkov@amd.com
Cc: Alexander.Deucher@amd.com, Xinmei.Huang@amd.com,
Xiaojian.Du@amd.com, Li.Meng@amd.com, linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 6/7] cpufreq:amd-pstate: add suspend and resume callback for passive mode
Date: Fri, 26 Jan 2024 09:52:51 -0600 [thread overview]
Message-ID: <580bc2a0-8621-4147-a7dd-0cc0bd54f9fa@amd.com> (raw)
In-Reply-To: <fa430f6288744c760145f4acab952c2bd0f947ad.1706255676.git.perry.yuan@amd.com>
On 1/26/2024 02:08, Perry Yuan wrote:
> From: Perry Yuan <Perry.Yuan@amd.com>
>
> Add suspend and resume support for `passive` mode driver which can save
> the previous CPU Pstate values and restore them while resuming, on some
> old platforms, the highest perf needs to be restored from driver side,
> otherwise the highest frequency could be changed during suspend.
So this sounds like a BIOS bug, right? Do you know how far back this
problem exists? Should it be a quirked behavior to only run on the
broken platforms so we don't need to run the callback on modern ones
without it?
>
> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
> ---
> drivers/cpufreq/amd-pstate.c | 48 ++++++++++++++++++++++++++++++++----
> 1 file changed, 43 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 5cbbc2999d9a..bba7640d46e0 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -785,23 +785,61 @@ static int amd_pstate_cpu_exit(struct cpufreq_policy *policy)
>
> static int amd_pstate_cpu_resume(struct cpufreq_policy *policy)
> {
> + struct cppc_perf_ctrls perf_ctrls;
> + struct amd_cpudata *cpudata = policy->driver_data;
> + u64 value, max_perf;
> int ret;
>
> - ret = amd_pstate_enable(true);
> - if (ret)
> - pr_err("failed to enable amd-pstate during resume, return %d\n", ret);
> + if (cpudata->suspended) {
> + mutex_lock(&amd_pstate_driver_lock);
>
> - return ret;
> + ret = amd_pstate_enable(true);
> + if (ret) {
> + pr_err("failed to enable amd-pstate during resume, return %d\n", ret);
> + mutex_unlock(&amd_pstate_driver_lock);
> + return ret;
> + }
This /looks/ like an unintended logic change to me. Previously
amd_pstate_enable(true) would be called in all modes, but now it will
only be called in passive mode.
Is that right?
> +
> + value = READ_ONCE(cpudata->cppc_req_cached);
> + max_perf = READ_ONCE(cpudata->highest_perf);
> +
> + if (boot_cpu_has(X86_FEATURE_CPPC)) {
> + wrmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, value);
> + } else {
> + perf_ctrls.max_perf = max_perf;
> + cppc_set_perf(cpudata->cpu, &perf_ctrls);
> + }
> +
> + cpudata->suspended = false;
> + mutex_unlock(&amd_pstate_driver_lock);
> + }
> +
> + return 0;
> }
>
> static int amd_pstate_cpu_suspend(struct cpufreq_policy *policy)
> {
> + struct amd_cpudata *cpudata = policy->driver_data;
> int ret;
>
> + /* avoid suspending when EPP is not enabled */
The logic seems right, but shouldn't the comment be:
/* only run suspend callbacks for passive mode */
Because this stuff won't run in guided mode or disable mode either
> + if (cppc_state != AMD_PSTATE_PASSIVE)
> + return 0;
> +
> + mutex_lock(&amd_pstate_driver_lock);
> +
> + /* set this flag to avoid calling core offline function
> + * when system is suspending, use this flag to skip offline function
> + * called
> + */
> + cpudata->suspended = true;
> +
> ret = amd_pstate_enable(false);
> if (ret)
> pr_err("failed to disable amd-pstate during suspend, return %d\n", ret);
>
> + mutex_unlock(&amd_pstate_driver_lock);
> +
> return ret;
> }
>
> @@ -1460,7 +1498,7 @@ static int amd_pstate_epp_suspend(struct cpufreq_policy *policy)
> if (cppc_state != AMD_PSTATE_ACTIVE)
> return 0;
>
> - /* set this flag to avoid setting core offline*/
> + /* set this flag to avoid setting core offline */
> cpudata->suspended = true;
>
> /* disable CPPC in lowlevel firmware */
next prev parent reply other threads:[~2024-01-26 15:52 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-26 8:08 [PATCH 0/7] AMD Pstate Driver Core Performance Boost Perry Yuan
2024-01-26 8:08 ` [PATCH 1/7] cpufreq: amd-pstate: remove set_boost callback for passive mode Perry Yuan
2024-01-26 15:45 ` Mario Limonciello
2024-01-29 4:46 ` Yuan, Perry
2024-01-26 8:08 ` [PATCH 2/7] cpufreq: amd-pstate: initialize new core precision boost state Perry Yuan
2024-01-26 16:01 ` Mario Limonciello
2024-01-27 19:01 ` kernel test robot
2024-02-11 18:19 ` kernel test robot
2024-02-14 6:37 ` Gautham R. Shenoy
2024-01-26 8:08 ` [PATCH 3/7] cpufreq: amd-pstate: implement cpb_boost sysfs entry for boost control Perry Yuan
2024-01-26 15:56 ` Mario Limonciello
2024-01-29 5:22 ` Yuan, Perry
2024-01-26 8:08 ` [PATCH 4/7] cpufreq: amd-pstate: fix max_perf calculation for amd_get_max_freq() Perry Yuan
2024-01-26 15:54 ` Mario Limonciello
2024-01-29 5:16 ` Yuan, Perry
2024-01-26 8:08 ` [PATCH 5/7] cpufreq: amd-pstate: fix the MSR highest perf will be reset issue while cpb boost off Perry Yuan
2024-01-26 8:08 ` [PATCH 6/7] cpufreq:amd-pstate: add suspend and resume callback for passive mode Perry Yuan
2024-01-26 15:52 ` Mario Limonciello [this message]
2024-01-26 8:08 ` [PATCH 7/7] Documentation: cpufreq: amd-pstate: introduce the new cpu boost control method Perry Yuan
2024-01-26 15:47 ` Mario Limonciello
2024-01-29 5:07 ` Yuan, Perry
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