linux-kernel - Re: [PATCH 1/8] cpupower: Update msr

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Date:   Fri, 22 Jan 2021 13:17:17 -0700
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Nathan Fontenot <nathan.fontenot@....com>, rrichter@....com,
        shuah@...nel.org, linux-kernel@...r.kernel.org, trenn@...e.com,
        linux-pm@...r.kernel.org, Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH 1/8] cpupower: Update msr_pstate union struct naming

On 1/22/21 10:38 AM, Nathan Fontenot wrote:
> The msr_pstate union struct named fam17h_bits is misleading since
> this is the struct to use for all families >= 0x17, not just
> for family 0x17. Rename the bits structs to be 'pstate' (for pre
> family 17h CPUs) and 'pstatedef' (for CPUs since fam 17h) to align
> closer with PPR/BDKG naming.

What is PPR/PDKG - would be helpful to know what it is and provide
link to the doc if applicable.
> 
> There are no functional changes as part of this update.
> 
> Signed-off-by: Nathan Fontenot <nathan.fontenot@....com>
> ---
>   tools/power/cpupower/utils/helpers/amd.c |   26 ++++++++++++++------------
>   1 file changed, 14 insertions(+), 12 deletions(-)
> 
> diff --git a/tools/power/cpupower/utils/helpers/amd.c b/tools/power/cpupower/utils/helpers/amd.c
> index 7c4f83a8c973..34368436bbd6 100644
> --- a/tools/power/cpupower/utils/helpers/amd.c
> +++ b/tools/power/cpupower/utils/helpers/amd.c
> @@ -13,7 +13,8 @@
>   #define MSR_AMD_PSTATE		0xc0010064
>   #define MSR_AMD_PSTATE_LIMIT	0xc0010061
>   
> -union msr_pstate {
> +union core_pstate {
> +	/* pre fam 17h: */
>   	struct {
>   		unsigned fid:6;
>   		unsigned did:3;
> @@ -26,7 +27,8 @@ union msr_pstate {
>   		unsigned idddiv:2;
>   		unsigned res3:21;
>   		unsigned en:1;
> -	} bits;
> +	} pstate;
> +	/* since fam 17h: */
>   	struct {
>   		unsigned fid:8;
>   		unsigned did:6;
> @@ -35,36 +37,36 @@ union msr_pstate {
>   		unsigned idddiv:2;
>   		unsigned res1:31;
>   		unsigned en:1;
> -	} fam17h_bits;
> +	} pstatedef;

Does pstatedef indicate this is pstate default?

>   	unsigned long long val;
>   };
>   
> -static int get_did(int family, union msr_pstate pstate)
> +static int get_did(int family, union core_pstate pstate)
>   {
>   	int t;
>   
>   	if (family == 0x12)
>   		t = pstate.val & 0xf;
>   	else if (family == 0x17 || family == 0x18)
> -		t = pstate.fam17h_bits.did;
> +		t = pstate.pstatedef.did;
>   	else
> -		t = pstate.bits.did;
> +		t = pstate.pstate.did;
>   
>   	return t;
>   }
>   
> -static int get_cof(int family, union msr_pstate pstate)
> +static int get_cof(int family, union core_pstate pstate)
>   {
>   	int t;
>   	int fid, did, cof;
>   
>   	did = get_did(family, pstate);
>   	if (family == 0x17 || family == 0x18) {
> -		fid = pstate.fam17h_bits.fid;
> +		fid = pstate.pstatedef.fid;
>   		cof = 200 * fid / did;
>   	} else {
>   		t = 0x10;
> -		fid = pstate.bits.fid;
> +		fid = pstate.pstate.fid;
>   		if (family == 0x11)
>   			t = 0x8;
>   		cof = (100 * (fid + t)) >> did;
> @@ -89,7 +91,7 @@ int decode_pstates(unsigned int cpu, unsigned int cpu_family,
>   		   int boost_states, unsigned long *pstates, int *no)
>   {
>   	int i, psmax, pscur;
> -	union msr_pstate pstate;
> +	union core_pstate pstate;
>   	unsigned long long val;
>   
>   	/* Only read out frequencies from HW when CPU might be boostable
> @@ -119,9 +121,9 @@ int decode_pstates(unsigned int cpu, unsigned int cpu_family,
>   		}
>   		if (read_msr(cpu, MSR_AMD_PSTATE + i, &pstate.val))
>   			return -1;
> -		if ((cpu_family == 0x17) && (!pstate.fam17h_bits.en))
> +		if ((cpu_family == 0x17) && (!pstate.pstatedef.en))
>   			continue;
> -		else if (!pstate.bits.en)
> +		else if (!pstate.pstate.en)
>   			continue;
>   
>   		pstates[i] = get_cof(cpu_family, pstate);
> 
> 

thanks,
-- Shuah