[PATCH 0/2 v2] intel_pstate: skip this driver if hit Sun X86 servers

[PATCH 0/2 v2] intel_pstate: skip this driver if hit Sun X86 servers

[Ethan Zhao]

Oracle Sun servers(X86) have power capping features that work via ACPI _PPC method,
patch No.1 is used to skip this driver if Oracle Sun server and _PPC detected. 
Patch No.2 introduces a kernel command line  parameter for those who would like
to enable intel_pstate on Sun X86 servers and be aware of the risk.


Compiled and tested with stable-3.18-rc5 on Oracle Sun server X4-2.
--
Ethan Zhao (2):
  intel_pstate: skip this driver if Sun server has _PPC method
  intel_pstate: add kernel parameter to enable loading on Sun X86
    servers.

 Documentation/kernel-parameters.txt |  3 +++
 drivers/cpufreq/intel_pstate.c      | 24 ++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

-- 
1.8.3.1

[PATCH 1/2 v2] intel_pstate: skip this driver if Sun server has _PPC method

[Ethan Zhao]

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@oracle.com>

v2: only match ORACLE oem id.
---
 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..dacc15a 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, "", ""},
 };
 
@@ -970,11 +986,15 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
 		    intel_pstate_no_acpi_pss())
 			return true;
 	}
+	if (!strncmp(hdr.oem_id, vendor_info[1].oem_id, ACPI_OEM_ID_SIZE) &&
+		intel_pstate_has_acpi_ppc())
+		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)
-- 
1.8.3.1

[PATCH 2/2 v2] intel_pstate: add kernel parameter to enable loading on Sun X86 servers.

[Ethan Zhao]

To force loading on Oracle Sun X86 servers, provide one kernel command line
parameter

  intel_pstate = onora

For those who be aware of the risk doing so.

Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com>

v2: change the command line parameter naming to specific to Oracle Sun servers.
---
 Documentation/kernel-parameters.txt | 3 +++
 drivers/cpufreq/intel_pstate.c      | 6 +++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 479f332..e4b1b81 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
+		       onora
+		         Enable loading intel_pstate on Oracle Sun Servers(X86).
+			 only for those who be aware of the risk.
 
 	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 dacc15a..f28c725 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -866,6 +866,7 @@ static struct cpufreq_driver intel_pstate_driver = {
 };
 
 static int __initdata no_load;
+static unsigned int  load_on_sun;
 
 static int intel_pstate_msrs_not_valid(void)
 {
@@ -987,7 +988,8 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
 			return true;
 	}
 	if (!strncmp(hdr.oem_id, vendor_info[1].oem_id, ACPI_OEM_ID_SIZE) &&
-		intel_pstate_has_acpi_ppc())
+		intel_pstate_has_acpi_ppc() &&
+		!load_on_sun)
 		return true;
 
 	return false;
@@ -1061,6 +1063,8 @@ static int __init intel_pstate_setup(char *str)
 
 	if (!strcmp(str, "disable"))
 		no_load = 1;
+	if (!strcmp(str, "onora"))
+		load_on_sun = 1;
 	return 0;
 }
 early_param("intel_pstate", intel_pstate_setup);
-- 
1.8.3.1