linux-kernel - Re: [PATCH v5 04/11] ACPI: CPPC: Extend cppc_set_epp_perf() to support auto

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <81f6409e-7909-44f7-9618-5f263b297ce9@huawei.com>
Date: Thu, 25 Dec 2025 11:56:04 +0800
From: "zhenglifeng (A)" <zhenglifeng1@...wei.com>
To: Sumit Gupta <sumitg@...dia.com>, <rafael@...nel.org>,
	<viresh.kumar@...aro.org>, <lenb@...nel.org>, <robert.moore@...el.com>,
	<corbet@....net>, <pierre.gondois@....com>, <rdunlap@...radead.org>,
	<ray.huang@....com>, <gautham.shenoy@....com>, <mario.limonciello@....com>,
	<perry.yuan@....com>, <ionela.voinescu@....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>
CC: <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 v5 04/11] ACPI: CPPC: Extend cppc_set_epp_perf() to
 support auto_sel and epp

On 2025/12/23 20:13, 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.
> 
> Also update EPP constants for better clarity:
> - Add CPPC_EPP_PERFORMANCE_PREF (0x00) for performance preference
> - Add CPPC_EPP_ENERGY_EFFICIENCY_PREF (0xFF) for energy efficiency
> 
> Signed-off-by: Sumit Gupta <sumitg@...dia.com>
> ---
>  drivers/acpi/cppc_acpi.c | 35 +++++++++++++++++++++++++++++------
>  include/acpi/cppc_acpi.h |  3 ++-
>  2 files changed, 31 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index a4e89fe6aab5..403ee988a8c6 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -1556,6 +1556,8 @@ 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) {
> @@ -1566,6 +1568,11 @@ 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);
> @@ -1590,14 +1597,30 @@ int cppc_set_epp_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls, bool enable)
>  		/* after writing CPC, transfer the ownership of PCC to platform */
>  		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);
> +	} else if (osc_cpc_flexible_adr_space_confirmed) {
> +		if (!epp_ffh_sysmem && !autosel_ffh_sysmem) {
> +			ret = -EOPNOTSUPP;
> +		} else {

I think this can do the same thing:

	} else if (osc_cpc_flexible_adr_space_confirmed &&
		   (epp_ffh_sysmem || autosel_ffh_sysmem)) {

and reduce the levels of indentation.

> +			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;
> +			}
> +		}
>  	} else {
> -		ret = -ENOTSUPP;
> -		pr_debug("_CPC in PCC and _CPC in FFH are not supported\n");
> +		ret = -EOPNOTSUPP;
>  	}
>  
> +	if (ret == -EOPNOTSUPP)
> +		pr_debug("CPU%d: _CPC not in PCC/FFH/SystemMemory\n", cpu);
> +
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(cppc_set_epp_perf);

The code below is unrelated to the code above and should ideally be
separated into a separate patch I think.

> @@ -1609,7 +1632,7 @@ EXPORT_SYMBOL_GPL(cppc_set_epp_perf);
>   */
>  int cppc_set_epp(int cpu, u64 epp_val)
>  {
> -	if (epp_val > CPPC_ENERGY_PERF_MAX)
> +	if (epp_val > CPPC_EPP_ENERGY_EFFICIENCY_PREF)
>  		return -EINVAL;
>  
>  	return cppc_set_reg_val(cpu, ENERGY_PERF, epp_val);
> diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
> index 12a1dc31bf2a..2860a0252313 100644
> --- a/include/acpi/cppc_acpi.h
> +++ b/include/acpi/cppc_acpi.h
> @@ -39,7 +39,8 @@
>  /* CPPC_AUTO_ACT_WINDOW_MAX_SIG is 127, so 128 and 129 will decay to 127 when writing */
>  #define CPPC_AUTO_ACT_WINDOW_SIG_CARRY_THRESH 129
>  
> -#define CPPC_ENERGY_PERF_MAX	(0xFF)
> +#define CPPC_EPP_PERFORMANCE_PREF		0x00
> +#define CPPC_EPP_ENERGY_EFFICIENCY_PREF		0xFF
>  
>  /* Each register has the folowing format. */
>  struct cpc_reg {