linux-kernel - Re: [PATCH v6 5/9] ACPI: CPPC: Extend cppc_set_epp

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Message-ID: <a7a4d351-eed3-4ea6-a84f-e525b7ac13a6@huawei.com>
Date: Thu, 22 Jan 2026 17:18:42 +0800
From: "zhenglifeng (A)" <zhenglifeng1@...wei.com>
To: Sumit Gupta <sumitg@...dia.com>
CC: <rafael@...nel.org>, <viresh.kumar@...aro.org>, <pierre.gondois@....com>,
	<ionela.voinescu@....com>, <lenb@...nel.org>, <robert.moore@...el.com>,
	<corbet@....net>, <rdunlap@...radead.org>, <ray.huang@....com>,
	<gautham.shenoy@....com>, <mario.limonciello@....com>, <perry.yuan@....com>,
	<zhanjie9@...ilicon.com>, <linux-pm@...r.kernel.org>,
	<linux-acpi@...r.kernel.org>, <linux-doc@...r.kernel.org>,
	<acpica-devel@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
	<linux-tegra@...r.kernel.org>, <treding@...dia.com>, <jonathanh@...dia.com>,
	<vsethi@...dia.com>, <ksitaraman@...dia.com>, <sanjayc@...dia.com>,
	<nhartman@...dia.com>, <bbasu@...dia.com>
Subject: Re: [PATCH v6 5/9] ACPI: CPPC: Extend cppc_set_epp_perf() for
 FFH/SystemMemory

On 2026/1/20 22:56, Sumit Gupta wrote:
> Extend cppc_set_epp_perf() to write both auto_sel and energy_perf
> registers when they are in FFH or SystemMemory address space.
> 
> This keeps the behavior consistent with PCC case where both registers
> are already updated together, but was missing for FFH/SystemMemory.
> 
> Signed-off-by: Sumit Gupta <sumitg@...dia.com>
> ---
>  drivers/acpi/cppc_acpi.c | 24 +++++++++++++++++++++---
>  1 file changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index de35aeb07833..45c6bd6ec24b 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -1562,6 +1562,8 @@ int cppc_set_epp_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls, bool enable)
>  	struct cpc_register_resource *auto_sel_reg;
>  	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
>  	struct cppc_pcc_data *pcc_ss_data = NULL;
> +	bool autosel_ffh_sysmem;
> +	bool epp_ffh_sysmem;
>  	int ret;
>  
>  	if (!cpc_desc) {
> @@ -1572,6 +1574,11 @@ int cppc_set_epp_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls, bool enable)
>  	auto_sel_reg = &cpc_desc->cpc_regs[AUTO_SEL_ENABLE];
>  	epp_set_reg = &cpc_desc->cpc_regs[ENERGY_PERF];
>  
> +	epp_ffh_sysmem = CPC_SUPPORTED(epp_set_reg) &&
> +		(CPC_IN_FFH(epp_set_reg) || CPC_IN_SYSTEM_MEMORY(epp_set_reg));
> +	autosel_ffh_sysmem = CPC_SUPPORTED(auto_sel_reg) &&
> +		(CPC_IN_FFH(auto_sel_reg) || CPC_IN_SYSTEM_MEMORY(auto_sel_reg));
> +
>  	if (CPC_IN_PCC(epp_set_reg) || CPC_IN_PCC(auto_sel_reg)) {
>  		if (pcc_ss_id < 0) {
>  			pr_debug("Invalid pcc_ss_id for CPU:%d\n", cpu);
> @@ -1597,11 +1604,22 @@ int cppc_set_epp_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls, bool enable)
>  		ret = send_pcc_cmd(pcc_ss_id, CMD_WRITE);
>  		up_write(&pcc_ss_data->pcc_lock);
>  	} else if (osc_cpc_flexible_adr_space_confirmed &&
> -		   CPC_SUPPORTED(epp_set_reg) && CPC_IN_FFH(epp_set_reg)) {
> -		ret = cpc_write(cpu, epp_set_reg, perf_ctrls->energy_perf);
> +		   (epp_ffh_sysmem || autosel_ffh_sysmem)) {
> +		if (autosel_ffh_sysmem) {
> +			ret = cpc_write(cpu, auto_sel_reg, enable);
> +			if (ret)
> +				return ret;
> +		}
> +
> +		if (epp_ffh_sysmem) {
> +			ret = cpc_write(cpu, epp_set_reg,
> +					perf_ctrls->energy_perf);
> +			if (ret)
> +				return ret;
> +		}

Don't know if such a scenario exists, but if one of them is in PCC and the
other is in FFH or system memory, only the one in PCC will be updated
based on your modifications.

>  	} else {
>  		ret = -ENOTSUPP;
> -		pr_debug("_CPC in PCC and _CPC in FFH are not supported\n");
> +		pr_debug("_CPC in PCC/FFH/SystemMemory are not supported\n");
>  	}
>  
>  	return ret;