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Date: Thu, 20 Nov 2014 23:44:56 -0500
From: Linda Knippers <ljklists@...il.com>
To: ethan zhao <ethan.zhao@...cle.com>,
Dirk Brandewie <dirk.brandewie@...il.com>
CC: Linda Knippers <linda.knippers@...com>, viresh.kumar@...aro.org,
rjw@...ysocki.net, corbet@....net, 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 11/20/2014 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.
> 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".
>
>>
>> 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?
-- 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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