linux-kernel - Re: [PATCH 2/2] cpufreq/amd-pstate: Fix the scaling_min/max_freq setting on shared memory CPPC systems

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Date: Wed, 26 Jun 2024 10:54:34 +0530
From: Gautham R.Shenoy <gautham.shenoy@....com>
To: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>, <rafael@...nel.org>,
	<viresh.kumar@...aro.org>, <mario.limonciello@....com>, <perry.yuan@....com>,
	<skhan@...uxfoundation.org>, <li.meng@....com>, <ray.huang@....com>
CC: <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Dhananjay
 Ugwekar" <Dhananjay.Ugwekar@....com>, <darcari@...hat.com>
Subject: Re: [PATCH 2/2] cpufreq/amd-pstate: Fix the scaling_min/max_freq
 setting on shared memory CPPC systems

Dhananjay Ugwekar <Dhananjay.Ugwekar@....com> writes:

> On shared memory CPPC systems, with amd_pstate=active mode, the change
> in scaling_min/max_freq doesn't get written to the shared memory
> region. Due to this, the writes to the scaling_min/max_freq sysfs file
> don't take effect. Fix this by propagating the scaling_min/max_freq
> changes to the shared memory region.
>
> Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors")
> Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>

Please add the following in your v2:

Reported-by: David Arcari <darcari@...hat.com>

> ---
>  drivers/cpufreq/amd-pstate.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 9ad62dbe8bfb..7c1c96abe5bd 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -264,6 +264,15 @@ static int amd_pstate_set_epp(struct amd_cpudata *cpudata, u32 epp)
>  			cpudata->epp_cached = epp;
>  	} else {
>  		perf_ctrls.energy_perf = epp;
> +		perf_ctrls.max_perf = cpudata->max_limit_perf;
> +		perf_ctrls.min_perf = cpudata->min_limit_perf;
> +		perf_ctrls.desired_perf = 0U;
> +
> +		ret = cppc_set_perf(cpudata->cpu, &perf_ctrls);
> +		if (ret) {
> +			pr_debug("failed to set min max limits (%d)\n", ret);
> +			return ret;
> +		}
>  		ret = cppc_set_epp_perf(cpudata->cpu, &perf_ctrls, 1);
>  		if (ret) {
>  			pr_debug("failed to set energy perf value (%d)\n", ret);
> @@ -1547,6 +1556,7 @@ static void amd_pstate_epp_update_limit(struct cpufreq_policy *policy)
>  	}
>  
>  	WRITE_ONCE(cpudata->cppc_req_cached, value);
> +
>  	amd_pstate_set_epp(cpudata, epp);
>  }
>  
> -- 

--
Thanks and Regards
gautham.