Merge branches 'pm-opp', 'pm-cpufreq' and 'pm-tools'

rafaeljw · rafaeljw · commit 2ec1c17cadd0 · 2014-12-18T18:44:53.000+01:00
* pm-opp:
  PM / OPP: do error handling at the bottom of dev_pm_opp_add_dynamic()
  PM / OPP: handle allocation of device_opp in a separate routine
  PM / OPP: reuse find_device_opp() instead of duplicating code
  PM / OPP: Staticize __dev_pm_opp_remove()
  PM / OPP: replace kfree with kfree_rcu while freeing 'struct device_opp'

* pm-cpufreq:
  MAINTAINERS: add entry for intel_pstate
  intel_pstate: Add a few comments
  intel_pstate: add kernel parameter to force loading

* pm-tools:
  Revert "tools: cpupower: fix return checks for sysfs_get_idlestate_count()"
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
@@ -1446,6 +1446,15 @@ 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
+		       force
+			 Enable intel_pstate on systems that prohibit it by default
+			 in favor of acpi-cpufreq. Forcing the intel_pstate driver
+			 instead of acpi-cpufreq may disable platform features, such
+			 as thermal controls and power capping, that rely on ACPI
+			 P-States information being indicated to OSPM and therefore
+			 should be used with caution. This option does not work with
+			 processors that aren't supported by the intel_pstate driver
+			 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
 		       no_hwp
 		         Do not enable hardware P state control (HWP)
 			 if available.
diff --git a/MAINTAINERS b/MAINTAINERS
@@ -4869,6 +4869,12 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux.git
 S:	Supported
 F:	drivers/idle/intel_idle.c
 
+INTEL PSTATE DRIVER
+M:	Kristen Carlson Accardi <kristen@linux.intel.com>
+L:	linux-pm@vger.kernel.org
+S:	Supported
+F:	drivers/cpufreq/intel_pstate.c
+
 INTEL FRAMEBUFFER DRIVER (excluding 810 and 815)
 M:	Maik Broemme <mbroemme@plusserver.de>
 L:	linux-fbdev@vger.kernel.org
diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
@@ -84,7 +84,11 @@ struct dev_pm_opp {
  *
  * This is an internal data structure maintaining the link to opps attached to
  * a device. This structure is not meant to be shared to users as it is
- * meant for book keeping and private to OPP library
+ * meant for book keeping and private to OPP library.
+ *
+ * Because the opp structures can be used from both rcu and srcu readers, we
+ * need to wait for the grace period of both of them before freeing any
+ * resources. And so we have used kfree_rcu() from within call_srcu() handlers.
  */
 struct device_opp {
 	struct list_head node;
@@ -382,12 +386,34 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor);
 
+static struct device_opp *add_device_opp(struct device *dev)
+{
+	struct device_opp *dev_opp;
+
+	/*
+	 * Allocate a new device OPP table. In the infrequent case where a new
+	 * device is needed to be added, we pay this penalty.
+	 */
+	dev_opp = kzalloc(sizeof(*dev_opp), GFP_KERNEL);
+	if (!dev_opp)
+		return NULL;
+
+	dev_opp->dev = dev;
+	srcu_init_notifier_head(&dev_opp->srcu_head);
+	INIT_LIST_HEAD(&dev_opp->opp_list);
+
+	/* Secure the device list modification */
+	list_add_rcu(&dev_opp->node, &dev_opp_list);
+	return dev_opp;
+}
+
 static int dev_pm_opp_add_dynamic(struct device *dev, unsigned long freq,
 				  unsigned long u_volt, bool dynamic)
 {
 	struct device_opp *dev_opp = NULL;
 	struct dev_pm_opp *opp, *new_opp;
 	struct list_head *head;
+	int ret;
 
 	/* allocate new OPP node */
 	new_opp = kzalloc(sizeof(*new_opp), GFP_KERNEL);
@@ -408,27 +434,12 @@ static int dev_pm_opp_add_dynamic(struct device *dev, unsigned long freq,
 	/* Check for existing list for 'dev' */
 	dev_opp = find_device_opp(dev);
 	if (IS_ERR(dev_opp)) {
-		/*
-		 * Allocate a new device OPP table. In the infrequent case
-		 * where a new device is needed to be added, we pay this
-		 * penalty.
-		 */
-		dev_opp = kzalloc(sizeof(struct device_opp), GFP_KERNEL);
+		dev_opp = add_device_opp(dev);
 		if (!dev_opp) {
-			mutex_unlock(&dev_opp_list_lock);
-			kfree(new_opp);
-			dev_warn(dev,
-				"%s: Unable to create device OPP structure\n",
-				__func__);
-			return -ENOMEM;
+			ret = -ENOMEM;
+			goto free_opp;
 		}
 
-		dev_opp->dev = dev;
-		srcu_init_notifier_head(&dev_opp->srcu_head);
-		INIT_LIST_HEAD(&dev_opp->opp_list);
-
-		/* Secure the device list modification */
-		list_add_rcu(&dev_opp->node, &dev_opp_list);
 		head = &dev_opp->opp_list;
 		goto list_add;
 	}
@@ -447,15 +458,13 @@ static int dev_pm_opp_add_dynamic(struct device *dev, unsigned long freq,
 
 	/* Duplicate OPPs ? */
 	if (new_opp->rate == opp->rate) {
-		int ret = opp->available && new_opp->u_volt == opp->u_volt ?
+		ret = opp->available && new_opp->u_volt == opp->u_volt ?
 			0 : -EEXIST;
 
 		dev_warn(dev, "%s: duplicate OPPs detected. Existing: freq: %lu, volt: %lu, enabled: %d. New: freq: %lu, volt: %lu, enabled: %d\n",
 			 __func__, opp->rate, opp->u_volt, opp->available,
 			 new_opp->rate, new_opp->u_volt, new_opp->available);
-		mutex_unlock(&dev_opp_list_lock);
-		kfree(new_opp);
-		return ret;
+		goto free_opp;
 	}
 
 list_add:
@@ -469,6 +478,11 @@ static int dev_pm_opp_add_dynamic(struct device *dev, unsigned long freq,
 	 */
 	srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_ADD, new_opp);
 	return 0;
+
+free_opp:
+	mutex_unlock(&dev_opp_list_lock);
+	kfree(new_opp);
+	return ret;
 }
 
 /**
@@ -511,10 +525,11 @@ static void kfree_device_rcu(struct rcu_head *head)
 {
 	struct device_opp *device_opp = container_of(head, struct device_opp, rcu_head);
 
-	kfree(device_opp);
+	kfree_rcu(device_opp, rcu_head);
 }
 
-void __dev_pm_opp_remove(struct device_opp *dev_opp, struct dev_pm_opp *opp)
+static void __dev_pm_opp_remove(struct device_opp *dev_opp,
+				struct dev_pm_opp *opp)
 {
 	/*
 	 * Notify the changes in the availability of the operable
@@ -592,7 +607,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_remove);
 static int opp_set_availability(struct device *dev, unsigned long freq,
 		bool availability_req)
 {
-	struct device_opp *tmp_dev_opp, *dev_opp = ERR_PTR(-ENODEV);
+	struct device_opp *dev_opp;
 	struct dev_pm_opp *new_opp, *tmp_opp, *opp = ERR_PTR(-ENODEV);
 	int r = 0;
 
@@ -606,12 +621,7 @@ static int opp_set_availability(struct device *dev, unsigned long freq,
 	mutex_lock(&dev_opp_list_lock);
 
 	/* Find the device_opp */
-	list_for_each_entry(tmp_dev_opp, &dev_opp_list, node) {
-		if (dev == tmp_dev_opp->dev) {
-			dev_opp = tmp_dev_opp;
-			break;
-		}
-	}
+	dev_opp = find_device_opp(dev);
 	if (IS_ERR(dev_opp)) {
 		r = PTR_ERR(dev_opp);
 		dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r);
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
@@ -199,7 +199,14 @@ static signed int pid_calc(struct _pid *pid, int32_t busy)
 
 	pid->integral += fp_error;
 
-	/* limit the integral term */
+	/*
+	 * We limit the integral here so that it will never
+	 * get higher than 30.  This prevents it from becoming
+	 * too large an input over long periods of time and allows
+	 * it to get factored out sooner.
+	 *
+	 * The value of 30 was chosen through experimentation.
+	 */
 	integral_limit = int_tofp(30);
 	if (pid->integral > integral_limit)
 		pid->integral = integral_limit;
@@ -616,6 +623,11 @@ static void intel_pstate_get_min_max(struct cpudata *cpu, int *min, int *max)
 	if (limits.no_turbo || limits.turbo_disabled)
 		max_perf = cpu->pstate.max_pstate;
 
+	/*
+	 * performance can be limited by user through sysfs, by cpufreq
+	 * policy, or by cpu specific default values determined through
+	 * experimentation.
+	 */
 	max_perf_adj = fp_toint(mul_fp(int_tofp(max_perf), limits.max_perf));
 	*max = clamp_t(int, max_perf_adj,
 			cpu->pstate.min_pstate, cpu->pstate.turbo_pstate);
@@ -717,11 +729,29 @@ static inline int32_t intel_pstate_get_scaled_busy(struct cpudata *cpu)
 	u32 duration_us;
 	u32 sample_time;
 
+	/*
+	 * core_busy is the ratio of actual performance to max
+	 * max_pstate is the max non turbo pstate available
+	 * current_pstate was the pstate that was requested during
+	 * 	the last sample period.
+	 *
+	 * We normalize core_busy, which was our actual percent
+	 * performance to what we requested during the last sample
+	 * period. The result will be a percentage of busy at a
+	 * specified pstate.
+	 */
 	core_busy = cpu->sample.core_pct_busy;
 	max_pstate = int_tofp(cpu->pstate.max_pstate);
 	current_pstate = int_tofp(cpu->pstate.current_pstate);
 	core_busy = mul_fp(core_busy, div_fp(max_pstate, current_pstate));
 
+	/*
+	 * Since we have a deferred timer, it will not fire unless
+	 * we are in C0.  So, determine if the actual elapsed time
+	 * is significantly greater (3x) than our sample interval.  If it
+	 * is, then we were idle for a long enough period of time
+	 * to adjust our busyness.
+	 */
 	sample_time = pid_params.sample_rate_ms  * USEC_PER_MSEC;
 	duration_us = (u32) ktime_us_delta(cpu->sample.time,
 					   cpu->last_sample_time);
@@ -948,6 +978,7 @@ static struct cpufreq_driver intel_pstate_driver = {
 
 static int __initdata no_load;
 static int __initdata no_hwp;
+static unsigned int force_load;
 
 static int intel_pstate_msrs_not_valid(void)
 {
@@ -1094,7 +1125,8 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
 			case PSS:
 				return intel_pstate_no_acpi_pss();
 			case PPC:
-				return intel_pstate_has_acpi_ppc();
+				return intel_pstate_has_acpi_ppc() &&
+					(!force_load);
 			}
 	}
 
@@ -1175,6 +1207,8 @@ static int __init intel_pstate_setup(char *str)
 		no_load = 1;
 	if (!strcmp(str, "no_hwp"))
 		no_hwp = 1;
+	if (!strcmp(str, "force"))
+		force_load = 1;
 	return 0;
 }
 early_param("intel_pstate", intel_pstate_setup);
diff --git a/tools/power/cpupower/utils/cpuidle-info.c b/tools/power/cpupower/utils/cpuidle-info.c
@@ -22,13 +22,13 @@
 
 static void cpuidle_cpu_output(unsigned int cpu, int verbose)
 {
-	int idlestates, idlestate;
+	unsigned int idlestates, idlestate;
 	char *tmp;
 
 	printf(_ ("Analyzing CPU %d:\n"), cpu);
 
 	idlestates = sysfs_get_idlestate_count(cpu);
-	if (idlestates < 1) {
+	if (idlestates == 0) {
 		printf(_("CPU %u: No idle states\n"), cpu);
 		return;
 	}
@@ -100,10 +100,10 @@ static void cpuidle_general_output(void)
 static void proc_cpuidle_cpu_output(unsigned int cpu)
 {
 	long max_allowed_cstate = 2000000000;
-	int cstate, cstates;
+	unsigned int cstate, cstates;
 
 	cstates = sysfs_get_idlestate_count(cpu);
-	if (cstates < 1) {
+	if (cstates == 0) {
 		printf(_("CPU %u: No C-states info\n"), cpu);
 		return;
 	}

Original file line number	Diff line number	Diff line change
`@@ -22,13 +22,13 @@`
`22`	`22`
`23`	`23`	`static void cpuidle_cpu_output(unsigned int cpu, int verbose)`
`24`	`24`	`{`
`25`		`- int idlestates, idlestate;`
	`25`	`+ unsigned int idlestates, idlestate;`
`26`	`26`	`char *tmp;`
`27`	`27`
`28`	`28`	`printf(_ ("Analyzing CPU %d:\n"), cpu);`
`29`	`29`
`30`	`30`	`idlestates = sysfs_get_idlestate_count(cpu);`
`31`		`- if (idlestates < 1) {`
	`31`	`+ if (idlestates == 0) {`
`32`	`32`	`printf(_("CPU %u: No idle states\n"), cpu);`
`33`	`33`	`return;`
`34`	`34`	`}`
`@@ -100,10 +100,10 @@ static void cpuidle_general_output(void)`
`100`	`100`	`static void proc_cpuidle_cpu_output(unsigned int cpu)`
`101`	`101`	`{`
`102`	`102`	`long max_allowed_cstate = 2000000000;`
`103`		`- int cstate, cstates;`
	`103`	`+ unsigned int cstate, cstates;`
`104`	`104`
`105`	`105`	`cstates = sysfs_get_idlestate_count(cpu);`
`106`		`- if (cstates < 1) {`
	`106`	`+ if (cstates == 0) {`
`107`	`107`	`printf(_("CPU %u: No C-states info\n"), cpu);`
`108`	`108`	`return;`
`109`	`109`	`}`