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Date: Tue, 25 Nov 2014 08:33:08 +0800
From: ethan <ethan.kernel@...il.com>
To: Linda Knippers <linda.knippers@...com>
Cc: ethan zhao <ethan.zhao@...cle.com>,
Linda Knippers <ljklists@...il.com>,
Dirk Brandewie <dirk.brandewie@...il.com>,
"viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
"rjw@...ysocki.net" <rjw@...ysocki.net>,
"corbet@....net" <corbet@....net>,
"dirk.j.brandewie@...el.com" <dirk.j.brandewie@...el.com>,
"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 1/3] intel_pstate: skip the driver if Sun server has ACPI _PPC method
Linda，
> 在 2014年11月24日，23:54，Linda Knippers <linda.knippers@...com> 写道：
>
>> On 11/23/2014 8:41 PM, ethan zhao wrote:
>> Linda,
>>
>>> On 2014/11/21 12:44, Linda Knippers wrote:
>>>
>>>> On 11/20/2014 07:37 PM, ethan zhao wrote:
>>>> Dirk,
>>>>
>>>>> On 2014/11/21 0:50, Dirk Brandewie wrote:
>>>>>> 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
>>> Right. This patch breaks HP ProLiant platforms when they are
>>> configured to have the OS do power management. In that case,
>>> the firmware exposes _PPC information.
>> Okay, got it, The HP ProLiant has an option in BIOS could be enabled to "OS
>> PM", so
>> will export _PSS, _PPC, and this patch break this case.
>>
>>>
>>>> No , this patch checks the oem_id against 'ORACLE" first, will not
>>>> affect other vendors even they have _PPC.
>>> I don't think that's how your code works. This patch will match any
>>> vendor that is in the table, not just "ORACLE".
>> Will change patch to match the oem-id out of the loop, such as following , how
>> about it ?
>>
>> static bool intel_pstate_platform_pwr_mgmt_exists(void)
>> {
>> struct acpi_table_header hdr;
>> struct hw_vendor_info *v_info;
>>
>> if (acpi_disabled
>> || ACPI_FAILURE(acpi_get_table_header(ACPI_SIG_FADT, 0, &hdr)))
>> return false;
>>
>> for (v_info = vendor_info; v_info->valid; v_info++) {
>> if (!strncmp(hdr.oem_id, v_info->oem_id, ACPI_OEM_ID_SIZE)
>> && !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[1]->oem_id, ACPI_OEM_ID_SIZE) &&
>> intel_pstate_has_acpi_ppc())
>
> I really don't think you want to hard code a 1 there.
>
> I think you need to do what Dirk suggested, which is to expand the
> hw_vendor_info structure to specify the check that needs to be done
> for each entry. For a ProLiant, it would be to call intel_pstate_no_acpi_pss()
> and for an Oracle box, it would be to call intel_pstate_has_acpi_ppc().
>
thanks，will do that.
Ethan
> -- ljk
>
>> return true;
>>
>> return false;
>> }
>>
>>>>> What about extending the hw_vendor_info struct to include whether _PSS or
>>>> Except refer to ACPI DSDT, I don't know how to fill such info.
>>>>> _PPC should be done for the platform since it appears that oracle and HP
>>>>> have implemented similar functionality using two different methods.
>>>> Maybe Linda could answer this whether HP also has _PPC and should be
>>>> wept out.
>>>> But that doesn't happen with on the same box at the same time.
>>> I don't know how an Oracle box works but on a ProLiant, customers can
>>> choose to have platform power management or OS power management.
>>> When the platform is managing the power, we don't provide the _PSS
>>> information. Since our oem information is in the table and there is
>>> no _PSS, the intel_pstate driver doesn't stay loaded. That's what we want.
>>>
>>> When the platform configured to have the OS do the power management,
>>> the firmware has _PSS and _PPC and we want the intel_pstate driver,
>>> That's what your patch breaks. With your patch, the driver won't
>>> stay loaded because our platform is in the table and the check for
>>> _PPC passes.
>>>
>>> How does an Oracle box work?
>> Oracle Sun servers (X86) don't have the option in BIOS to change the PM mode
>> to firmware/OS,
>> The BIOS always has _PSS and _PPC exported to OS whatever 'soft power capping'
>> or 'hard power capping' enabled
>> in SP configuration web page. if the power policy violation happened, firmware
>> will notify OS via SCI with the changed _PPC
>> number.
>>
>> Thanks,
>> Ethan
>>>
>>> -- ljk
>>>
>>>> Thanks,
>>>> Ethan
>>>>>
>>>>>> 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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>
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