Re: [PATCH 1/1] cpufreq: intel_pstate: skip the driver if ACPI has power mgmt option

[adrian <adrian.huang@hp.com>]

Thanks, Dirk. The patch has been modified accordingly. 

Signed-off-by: Adrian Huang <adrian.huang@hp.com>
---
 drivers/cpufreq/intel_pstate.c | 80 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index badf620..8c00394 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -26,6 +26,8 @@
 #include <linux/fs.h>
 #include <linux/debugfs.h>
 #include <trace/events/power.h>
+#include <linux/acpi.h>
+#include <acpi/processor.h>
 
 #include <asm/div64.h>
 #include <asm/msr.h>
@@ -129,6 +131,18 @@ static struct perf_limits limits = {
 	.max_sysfs_pct = 100,
 };
 
+struct hw_vendor_info {
+	u16  valid;
+	char oem_id[ACPI_OEM_ID_SIZE];
+	char oem_table_id[ACPI_OEM_TABLE_ID_SIZE];
+};
+
+/* Hardware vendor-specific info that has its own power management modes */
+static struct hw_vendor_info vendor_info[] = {
+	{1, "HP    ", "ProLiant"},
+	{0, "", ""},
+};
+
 static inline void pid_reset(struct _pid *pid, int setpoint, int busy,
 			int deadband, int integral) {
 	pid->setpoint = setpoint;
@@ -700,6 +714,63 @@ static int intel_pstate_msrs_not_valid(void)
 
 	return 0;
 }
+
+static bool intel_pstate_no_acpi_pss(void)
+{
+	struct acpi_processor *pr;
+	union acpi_object *pss = NULL;
+	int i;
+
+	for_each_possible_cpu(i) {
+
+		pr = per_cpu(processors, i);
+
+		if (pr) {
+			struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER,
+							NULL };
+
+			if (ACPI_SUCCESS(acpi_evaluate_object(pr->handle,
+						"_PSS", NULL, &buffer))) {
+
+				pss = buffer.pointer;
+
+				if (pss && pss->type == ACPI_TYPE_PACKAGE) {
+					kfree(buffer.pointer);
+					return false;
+				}
+
+				kfree(buffer.pointer);
+			}
+		}
+	}
+
+	return true;
+}
+
+static bool intel_pstate_platform_pwr_mgmt_exists(void)
+{
+	struct acpi_table_header hdr;
+	struct hw_vendor_info *v_info;
+
+	if (acpi_get_table_header(ACPI_SIG_FADT, 0, &hdr) == AE_OK) {
+		for (v_info = vendor_info; v_info->valid; v_info++) {
+			/*
+			 * Check if the hardware/platform is in the
+			 * predefined vendor data.
+			 */
+			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)) {
+				if (intel_pstate_no_acpi_pss())
+					return true;
+			}
+		}
+	}
+
+	return false;
+}
+
 static int __init intel_pstate_init(void)
 {
 	int cpu, rc = 0;
@@ -708,6 +779,15 @@ static int __init intel_pstate_init(void)
 	if (no_load)
 		return -ENODEV;
 
+	if (!acpi_disabled) {
+		/*
+		 * Check if the platform has its own power management modes.
+		 * If so, the pstate cpufreq driver will be ignored.
+		 */
+		if (intel_pstate_platform_pwr_mgmt_exists())
+			return -ENODEV;
+	}
+
 	id = x86_match_cpu(intel_pstate_cpu_ids);
 	if (!id)
 		return -ENODEV;
-- 
1.8.1.2


於 一，2013-10-21 於 09:03 -0700，Dirk Brandewie 提到： 
> On 10/20/2013 10:27 PM, Adrian Huang wrote:
> >   static int __init intel_pstate_init(void)
> >   {
> >   	int cpu, rc = 0;
> > @@ -708,6 +779,15 @@ static int __init intel_pstate_init(void)
> >   	if (no_load)
> >   		return -ENODEV;
> >
> > +	if (!acpi_disabled) {
> > +		/*
> > +		 * Check if the platform has its own power management modes.
> > +		 * If so, the pstate cpufreq driver will be ignored.
> > +		 */
> > +		if (intel_pstate_platform_pwr_mgmt_exists())
> > +			return 0;
> 
> Please return -ENODEV here instead of 0
> 
> > +	}
> > +
> >   	id = x86_match_cpu(intel_pstate_cpu_ids);
> >   	if (!id)
> >   		return -ENODEV;
> >
>