linux-kernel - Re: [PATCH 1/3] intel_pstate: skip the driver if Sun server has ACPI

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Message-ID: <546E1BBE.7050906@intel.com>
Date:	Thu, 20 Nov 2014 08:50:06 -0800
From:	Dirk Brandewie <dirk.brandewie@...il.com>
To:	Linda Knippers <linda.knippers@...com>,
	Ethan Zhao <ethan.zhao@...cle.com>, viresh.kumar@...aro.org,
	rjw@...ysocki.net, corbet@....net
CC:	dirk.j.brandewie@...el.com, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	ethan.kernel@...il.com, joe.jin@...cle.com, brian.maly@...cle.com
Subject: Re: [PATCH 1/3] intel_pstate: skip the driver if Sun server has ACPI
 _PPC method

On 11/19/2014 12:22 PM, Linda Knippers wrote:
> On 11/18/2014 3:37 AM, Ethan Zhao wrote:
>> Oracle Sun X86 servers have dynamic power capping capability that works via
>> ACPI _PPC method etc, so skip loading this driver if Sun server has ACPI _PPC
>> enabled.
>>
>> Signed-off-by: Ethan Zhao <ethan.zhao@...cle.com>
>> ---
>>   drivers/cpufreq/intel_pstate.c | 20 ++++++++++++++++++++
>>   1 file changed, 20 insertions(+)
>>
>> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
>> index 27bb6d3..5498eb0 100644
>> --- a/drivers/cpufreq/intel_pstate.c
>> +++ b/drivers/cpufreq/intel_pstate.c
>> @@ -943,6 +943,21 @@ static bool intel_pstate_no_acpi_pss(void)
>>   	return true;
>>   }
>>
>> +static bool intel_pstate_has_acpi_ppc(void)
>> +{
>> +	int i;
>> +
>> +	for_each_possible_cpu(i) {
>> +		struct acpi_processor *pr = per_cpu(processors, i);
>> +
>> +		if (!pr)
>> +			continue;
>> +		if (acpi_has_method(pr->handle, "_PPC"))
>> +			return true;
>> +	}
>> +	return false;
>> +}
>> +
>>   struct hw_vendor_info {
>>   	u16  valid;
>>   	char oem_id[ACPI_OEM_ID_SIZE];
>> @@ -952,6 +967,7 @@ struct hw_vendor_info {
>>   /* Hardware vendor-specific info that has its own power management modes */
>>   static struct hw_vendor_info vendor_info[] = {
>>   	{1, "HP    ", "ProLiant"},
>> +	{1, "ORACLE", ""},
>>   	{0, "", ""},
>>   };
>>
>> @@ -969,12 +985,16 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
>>   		    !strncmp(hdr.oem_table_id, v_info->oem_table_id, ACPI_OEM_TABLE_ID_SIZE) &&
>>   		    intel_pstate_no_acpi_pss())
>>   			return true;
>> +		if (!strncmp(hdr.oem_id, v_info->oem_id, ACPI_OEM_ID_SIZE) &&
>> +			intel_pstate_has_acpi_ppc())
>
> We need try this on a few platforms to make sure this patch doesn't break the
> HP platforms that may or may not need this driver, depending on the BIOS settings.
>

It looks like HP systems would get swept up in this check too if they have _PPC

What about extending the hw_vendor_info struct to include whether _PSS or
_PPC should be done for the platform since it appears that oracle and HP
have implemented similar functionality using two different methods.


> I don't suppose you tested on a ProLiant too?
>
> -- ljk
>
>> +			return true;
>>   	}
>>
>>   	return false;
>>   }
>>   #else /* CONFIG_ACPI not enabled */
>>   static inline bool intel_pstate_platform_pwr_mgmt_exists(void) { return false; }
>> +static inline bool intel_pstate_has_acpi_ppc(void) { return false; }
>>   #endif /* CONFIG_ACPI */
>>
>>   static int __init intel_pstate_init(void)
>>
>

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