linux-kernel - Re: [PATCH 3/3] intel_pstate: add module and kernel command line parameter to ignore ACPI

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Message-Id: <41ADCDB8-C204-4661-833B-F68E7D687B61@gmail.com>
Date:	Thu, 20 Nov 2014 08:57:34 +0800
From:	ethan <ethan.kernel@...il.com>
To:	Kristen Carlson Accardi <kristen@...ux.intel.com>
Cc:	Ethan Zhao <ethan.zhao@...cle.com>,
	"<dirk.j.brandewie@...el.com>" <dirk.j.brandewie@...el.com>,
	"<viresh.kumar@...aro.org>" <viresh.kumar@...aro.org>,
	"<rjw@...ysocki.net>" <rjw@...ysocki.net>,
	"<corbet@....net>" <corbet@....net>,
	"<linux-doc@...r.kernel.org>" <linux-doc@...r.kernel.org>,
	"<linux-kernel@...r.kernel.org>" <linux-kernel@...r.kernel.org>,
	"<linux-pm@...r.kernel.org>" <linux-pm@...r.kernel.org>,
	"<joe.jin@...cle.com>" <joe.jin@...cle.com>,
	"<brian.maly@...cle.com>" <brian.maly@...cle.com>
Subject: Re: [PATCH 3/3] intel_pstate: add module and kernel command line parameter to ignore ACPI _PPC



> 在 2014年11月20日，03:05，Kristen Carlson Accardi <kristen@...ux.intel.com> 写道：
> 
> On Tue, 18 Nov 2014 17:37:06 +0900
> Ethan Zhao <ethan.zhao@...cle.com> wrote:
> 
>> Add kernel command line parameter
>> intel_pstate = ignore_acpi_ppc
>> and module parameter
>> ignore_acpi_ppc = 1
>> to allow driver to ignore the ACPI _PPC existence even for Sun x86 servers.
>> These parameter could be used for debug\test\workaround etc purpose.
>> 
>> Signed-off-by: Ethan Zhao <ethan.zhao@...cle.com>
> 
> What if we used a more generic parameter like "force" that would bypass
> any vendor specific checks and just load anyway?  This way we don't have
> to add new parameters everything some new thing shows up that we want to
> ignore.
> 
To be honest, I prefer more generic parameter. But to avoid the possible negative affect 
To another vendors. I back to this way.

Thanks,
Ethan
>> ---
>> Documentation/kernel-parameters.txt | 3 +++
>> drivers/cpufreq/intel_pstate.c      | 8 +++++++-
>> 2 files changed, 10 insertions(+), 1 deletion(-)
>> 
>> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
>> index 4c81a86..f502b85 100644
>> --- a/Documentation/kernel-parameters.txt
>> +++ b/Documentation/kernel-parameters.txt
>> @@ -1446,6 +1446,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>>               disable
>>                 Do not enable intel_pstate as the default
>>                 scaling driver for the supported processors
>> +               ignore_acpi_ppc
>> +             Ignore the existence of ACPI method _PPC for Sun x86 servers
>> +             and load the driver.
>> 
>>    intremap=    [X86-64, Intel-IOMMU]
>>            on    enable Interrupt Remapping (default)
>> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
>> index 7c5faea..388387b 100644
>> --- a/drivers/cpufreq/intel_pstate.c
>> +++ b/drivers/cpufreq/intel_pstate.c
>> @@ -870,6 +870,7 @@ static struct cpufreq_driver intel_pstate_driver = {
>> };
>> 
>> static int __initdata no_load;
>> +static unsigned int  ignore_acpi_ppc;
>> 
>> static int intel_pstate_msrs_not_valid(void)
>> {
>> @@ -990,7 +991,7 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
>>            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())
>> +            intel_pstate_has_acpi_ppc() && !ignore_acpi_ppc)
>>            return true;
>>    }
>> 
>> @@ -1066,11 +1067,16 @@ static int __init intel_pstate_setup(char *str)
>> 
>>    if (!strcmp(str, "disable"))
>>        no_load = 1;
>> +    if (!strcmp(str, "ignore_acpi_ppc"))
>> +        ignore_acpi_ppc = 1;
>>    return 0;
>> }
>> early_param("intel_pstate", intel_pstate_setup);
>> #endif
>> 
>> +module_param(ignore_acpi_ppc, uint, 0644);
>> +MODULE_PARM_DESC(ignore_acpi_ppc,
>> +    "value 0 or non-zero. non-zero -> ignore ACPI _PPC and load this driver");
>> MODULE_AUTHOR("Dirk Brandewie <dirk.j.brandewie@...el.com>");
>> MODULE_DESCRIPTION("'intel_pstate' - P state driver Intel Core processors");
>> MODULE_LICENSE("GPL");
> 
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