linux-kernel - RE: [PATCH] cpufreq: intel_pstate: Add additional OOB enabling bit

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Date:   Fri, 12 Jun 2020 07:11:00 -0700
From:   "Doug Smythies" <dsmythies@...us.net>
To:     "'Srinivas Pandruvada'" <srinivas.pandruvada@...ux.intel.com>,
        <lenb@...nel.org>, <viresh.kumar@...aro.org>, <rjw@...ysocki.net>
Cc:     <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] cpufreq: intel_pstate: Add additional OOB enabling bit

On 2020.06.11 10:49 Srinivas Pandruvada wrote:

> Add additional bit for OOB (Out of band) enabling of P-states. In this
> case intel_pstate shouldn't load. Currently, only "BIT(8) == 1" of the
> MSR MSR_MISC_PWR_MGMT is considered as OOB. Also add "BIT(18) == 1" as
> OOB condition.

Shouldn't those bits be defined in these files:
arch/x86/include/asm/msr-index.h
and
tools/arch/x86/include/asm/msr-index.h

?

By the way, I couldn't find those bits defined in Intel docs that I have.
 
> 
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
> ---
>  drivers/cpufreq/intel_pstate.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index 8e23a698ce04..f21761443c90 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -2686,8 +2686,8 @@ static bool __init intel_pstate_platform_pwr_mgmt_exists(void)
>  	id = x86_match_cpu(intel_pstate_cpu_oob_ids);
>  	if (id) {
>  		rdmsrl(MSR_MISC_PWR_MGMT, misc_pwr);
> -		if (misc_pwr & (1 << 8)) {
> -			pr_debug("Bit 8 in the MISC_PWR_MGMT MSR set\n");
> +		if ((misc_pwr & BIT(8)) || (misc_pwr & BIT(18))) {

And then those bit definitions used above.

> +			pr_debug("Bit 8 or 18 in the MISC_PWR_MGMT MSR set\n");

And then some insight also printed  with the debug message.
At least say "Out of Band".

>  			return true;
>  		}
>  	}
> --
> 2.24.1