linux-kernel - Re: [PATCH v6 1/8] ACPI: CPPC: Add IS_OPTIONAL_CPC_REG macro to judge if a cpc

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Message-ID: <7a3bda35-05a0-49ad-b014-1834a176a906@amd.com>
Date: Wed, 9 Apr 2025 13:53:25 -0500
From: Mario Limonciello <mario.limonciello@....com>
To: Lifeng Zheng <zhenglifeng1@...wei.com>, rafael@...nel.org,
 lenb@...nel.org, robert.moore@...el.com, viresh.kumar@...aro.org,
 gautham.shenoy@....com, ray.huang@....com, perry.yuan@....com,
 pierre.gondois@....com
Cc: acpica-devel@...ts.linux.dev, linux-acpi@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org, linuxarm@...wei.com,
 jonathan.cameron@...wei.com, zhanjie9@...ilicon.com, lihuisong@...wei.com,
 cenxinghai@...artners.com, hepeng68@...wei.com
Subject: Re: [PATCH v6 1/8] ACPI: CPPC: Add IS_OPTIONAL_CPC_REG macro to judge
 if a cpc_reg is optional

On 4/9/2025 1:56 AM, Lifeng Zheng wrote:
> In ACPI 6.5, s8.4.6.1 _CPC (Continuous Performance Control), whether each
> of the per-cpu cpc_regs[] is mendatory or optional is defined. Since the
mandatory
> CPC_SUPPORTED() check is only for optional cpc field, another macro to
> check if the field is optional is needed.
> 
> Reviewed-by: Pierre Gondois <pierre.gondois@....com>
> Signed-off-by: Lifeng Zheng <zhenglifeng1@...wei.com>
> ---
>   drivers/acpi/cppc_acpi.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index f193e713825a..39f019e265da 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -129,6 +129,20 @@ static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);
>   #define CPC_SUPPORTED(cpc) ((cpc)->type == ACPI_TYPE_INTEGER ?		\
>   				!!(cpc)->cpc_entry.int_value :		\
>   				!IS_NULL_REG(&(cpc)->cpc_entry.reg))
> +
> +/*
> + * Each bit indicates the optionality of the register in per-cpu
> + * cpc_regs[] with the corresponding index. 0 means mandatory and 1
> + * means optional.
> + */
> +#define REG_OPTIONAL (0x1FC7D0)
> +
> +/*
> + * Use the index of the register in per-cpu cpc_regs[] to check if
> + * it's an optional one.
> + */
> +#define IS_OPTIONAL_CPC_REG(reg_idx) (REG_OPTIONAL & (1U << (reg_idx)))
> +
>   /*
>    * Arbitrary Retries in case the remote processor is slow to respond
>    * to PCC commands. Keeping it high enough to cover emulators where