linux-kernel - Re: [PATCH] cpufreq: intel_pstate: warn if HWP Native mode and OOB mode are both set

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Date:   Fri, 14 Sep 2018 11:09:18 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     oceanhe@...o.com.cn, srinivas.pandruvada@...ux.intel.com
Cc:     lenb@...nel.org, viresh.kumar@...aro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Ocean He <hehy1@...ovo.com>
Subject: Re: [PATCH] cpufreq: intel_pstate: warn if HWP Native mode and OOB mode are both set

On Sunday, July 29, 2018 6:14:56 AM CEST oceanhe@...o.com.cn wrote:
> From: Ocean He <hehy1@...ovo.com>
> 
> Refer to Intel HWPM Compliance Guide (Document Number: 566474): Bit[6] or
> bit[8] of MSR MISC_PWR_MGMT is set only when BIOS select either HWP Native
> mode or HWP OOB mode. Bit[6] and bit[8] cannot be set both at the same
> time.
> 
> Add a warning message if intel_pstate detects both HWP Native mode and
> HWP OOB mode are set at the same time.
> 
> Signed-off-by: Ocean He <hehy1@...ovo.com>
> ---
>  drivers/cpufreq/intel_pstate.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index 3c39712..678d3f2 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -2455,8 +2455,12 @@ 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))
> +		if (misc_pwr & (1 << 8)) {
> +			if (misc_pwr & (1 << 6))
> +				pr_warn(FW_WARN
> +					"HWP Native mode and OOB mode cannot be set both at the same time.\n");
>  			return true;
> +		}
>  	}
>  
>  	idx = acpi_match_platform_list(plat_info);
> 

Srinivas, what do you think about this one?