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 13:27:52 +0530
From: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
To: "Gautham R.Shenoy" <gautham.shenoy@....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, darcari@...hat.com
Subject: Re: [PATCH 2/2] cpufreq/amd-pstate: Fix the scaling_min/max_freq
 setting on shared memory CPPC systems

Hello Gautham,

On 6/26/2024 10:54 AM, Gautham R.Shenoy wrote:
> 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>

Yup, will add.

Thanks,
Dhananjay

> 
>> ---
>>  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.