Index: linux-pm/drivers/base/power/sysfs.c
===================================================================
--- linux-pm.orig/drivers/base/power/sysfs.c
+++ linux-pm/drivers/base/power/sysfs.c
@@ -218,7 +218,14 @@ static ssize_t pm_qos_resume_latency_sho
 					  struct device_attribute *attr,
 					  char *buf)
 {
-	return sprintf(buf, "%d\n", dev_pm_qos_requested_resume_latency(dev));
+	s32 value = dev_pm_qos_requested_resume_latency(dev);
+
+	if (value == 0)
+		return sprintf(buf, "n/a\n");
+	else if (value == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
+		value = 0;
+
+	return sprintf(buf, "%d\n", value);
 }
 
 static ssize_t pm_qos_resume_latency_store(struct device *dev,
@@ -228,11 +235,19 @@ static ssize_t pm_qos_resume_latency_sto
 	s32 value;
 	int ret;
 
-	if (kstrtos32(buf, 0, &value))
-		return -EINVAL;
+	if (!kstrtos32(buf, 0, &value)) {
+		/*
+		 * Prevent users from writing negative or "no constraint" values
+		 * directly.
+		 */
+		if (value < 0 || value == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
+			return -EINVAL;
 
-	if (value < 0)
-		return -EINVAL;
+		if (value == 0)
+			value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;
+	} else if (!strcmp(buf, "n/a") || !strcmp(buf, "n/a\n")) {
+		value = 0;
+	}
 
 	ret = dev_pm_qos_update_request(dev->power.qos->resume_latency_req,
 					value);
Index: linux-pm/include/linux/pm_qos.h
===================================================================
--- linux-pm.orig/include/linux/pm_qos.h
+++ linux-pm/include/linux/pm_qos.h
@@ -27,16 +27,17 @@ enum pm_qos_flags_status {
 	PM_QOS_FLAGS_ALL,
 };
 
-#define PM_QOS_DEFAULT_VALUE -1
+#define PM_QOS_DEFAULT_VALUE	(-1)
+#define PM_QOS_LATENCY_ANY	S32_MAX
 
 #define PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE	(2000 * USEC_PER_SEC)
 #define PM_QOS_NETWORK_LAT_DEFAULT_VALUE	(2000 * USEC_PER_SEC)
 #define PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE	0
 #define PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE	0
 #define PM_QOS_RESUME_LATENCY_DEFAULT_VALUE	0
+#define PM_QOS_RESUME_LATENCY_NO_CONSTRAINT	PM_QOS_LATENCY_ANY
 #define PM_QOS_LATENCY_TOLERANCE_DEFAULT_VALUE	0
 #define PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT	(-1)
-#define PM_QOS_LATENCY_ANY			((s32)(~(__u32)0 >> 1))
 
 #define PM_QOS_FLAG_NO_POWER_OFF	(1 << 0)
 
Index: linux-pm/drivers/cpuidle/governors/menu.c
===================================================================
--- linux-pm.orig/drivers/cpuidle/governors/menu.c
+++ linux-pm/drivers/cpuidle/governors/menu.c
@@ -298,8 +298,8 @@ static int menu_select(struct cpuidle_dr
 		data->needs_update = 0;
 	}
 
-	/* resume_latency is 0 means no restriction */
-	if (resume_latency && resume_latency < latency_req)
+	if (resume_latency < latency_req &&
+	    resume_latency != PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
 		latency_req = resume_latency;
 
 	/* Special case when user has set very strict latency requirement */
Index: linux-pm/drivers/base/power/domain_governor.c
===================================================================
--- linux-pm.orig/drivers/base/power/domain_governor.c
+++ linux-pm/drivers/base/power/domain_governor.c
@@ -14,23 +14,20 @@
 static int dev_update_qos_constraint(struct device *dev, void *data)
 {
 	s64 *constraint_ns_p = data;
-	s32 constraint_ns = -1;
+	s64 constraint_ns = -1;
 
 	if (dev->power.subsys_data && dev->power.subsys_data->domain_data)
 		constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;
 
-	if (constraint_ns < 0) {
+	if (constraint_ns < 0)
 		constraint_ns = dev_pm_qos_read_value(dev);
-		constraint_ns *= NSEC_PER_USEC;
-	}
-	if (constraint_ns == 0)
+
+	if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
 		return 0;
 
-	/*
-	 * constraint_ns cannot be negative here, because the device has been
-	 * suspended.
-	 */
-	if (constraint_ns < *constraint_ns_p || *constraint_ns_p == 0)
+	constraint_ns *= NSEC_PER_USEC;
+
+	if (constraint_ns < *constraint_ns_p || *constraint_ns_p < 0)
 		*constraint_ns_p = constraint_ns;
 
 	return 0;
@@ -63,10 +60,14 @@ static bool default_suspend_ok(struct de
 
 	spin_unlock_irqrestore(&dev->power.lock, flags);
 
-	if (constraint_ns < 0)
+	if (constraint_ns == 0)
 		return false;
 
-	constraint_ns *= NSEC_PER_USEC;
+	if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
+		constraint_ns = -1;
+	else
+		constraint_ns *= NSEC_PER_USEC;
+
 	/*
 	 * We can walk the children without any additional locking, because
 	 * they all have been suspended at this point and their
@@ -76,14 +77,19 @@ static bool default_suspend_ok(struct de
 		device_for_each_child(dev, &constraint_ns,
 				      dev_update_qos_constraint);
 
-	if (constraint_ns > 0) {
-		constraint_ns -= td->suspend_latency_ns +
-				td->resume_latency_ns;
-		if (constraint_ns == 0)
-			return false;
+	if (constraint_ns < 0) {
+		/* The children have no constraints. */
+		td->effective_constraint_ns = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;
+		td->cached_suspend_ok = true;
+	} else {
+		constraint_ns -= td->suspend_latency_ns + td->resume_latency_ns;
+		if (constraint_ns > 0) {
+			td->effective_constraint_ns = constraint_ns;
+			td->cached_suspend_ok = true;
+		} else {
+			td->effective_constraint_ns = 0;
+		}
 	}
-	td->effective_constraint_ns = constraint_ns;
-	td->cached_suspend_ok = constraint_ns >= 0;
 
 	/*
 	 * The children have been suspended already, so we don't need to take
@@ -145,13 +151,14 @@ static bool __default_power_down_ok(stru
 		td = &to_gpd_data(pdd)->td;
 		constraint_ns = td->effective_constraint_ns;
 		/* default_suspend_ok() need not be called before us. */
-		if (constraint_ns < 0) {
+		if (constraint_ns < 0)
 			constraint_ns = dev_pm_qos_read_value(pdd->dev);
-			constraint_ns *= NSEC_PER_USEC;
-		}
-		if (constraint_ns == 0)
+
+		if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
 			continue;
 
+		constraint_ns *= NSEC_PER_USEC;
+
 		/*
 		 * constraint_ns cannot be negative here, because the device has
 		 * been suspended.
Index: linux-pm/drivers/base/power/runtime.c
===================================================================
--- linux-pm.orig/drivers/base/power/runtime.c
+++ linux-pm/drivers/base/power/runtime.c
@@ -253,7 +253,7 @@ static int rpm_check_suspend_allowed(str
 	    || (dev->power.request_pending
 			&& dev->power.request == RPM_REQ_RESUME))
 		retval = -EAGAIN;
-	else if (__dev_pm_qos_read_value(dev) < 0)
+	else if (__dev_pm_qos_read_value(dev) == 0)
 		retval = -EPERM;
 	else if (dev->power.runtime_status == RPM_SUSPENDED)
 		retval = 1;
Index: linux-pm/drivers/base/cpu.c
===================================================================
--- linux-pm.orig/drivers/base/cpu.c
+++ linux-pm/drivers/base/cpu.c
@@ -377,7 +377,8 @@ int register_cpu(struct cpu *cpu, int nu
 
 	per_cpu(cpu_sys_devices, num) = &cpu->dev;
 	register_cpu_under_node(num, cpu_to_node(num));
-	dev_pm_qos_expose_latency_limit(&cpu->dev, 0);
+	dev_pm_qos_expose_latency_limit(&cpu->dev,
+					PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);
 
 	return 0;
 }
Index: linux-pm/drivers/base/power/qos.c
===================================================================
--- linux-pm.orig/drivers/base/power/qos.c
+++ linux-pm/drivers/base/power/qos.c
@@ -189,7 +189,7 @@ static int dev_pm_qos_constraints_alloca
 	plist_head_init(&c->list);
 	c->target_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
 	c->default_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
-	c->no_constraint_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
+	c->no_constraint_value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;
 	c->type = PM_QOS_MIN;
 	c->notifiers = n;
 
Index: linux-pm/Documentation/ABI/testing/sysfs-devices-power
===================================================================
--- linux-pm.orig/Documentation/ABI/testing/sysfs-devices-power
+++ linux-pm/Documentation/ABI/testing/sysfs-devices-power
@@ -211,7 +211,9 @@ Description:
 		device, after it has been suspended at run time, from a resume
 		request to the moment the device will be ready to process I/O,
 		in microseconds.  If it is equal to 0, however, this means that
-		the PM QoS resume latency may be arbitrary.
+		the PM QoS resume latency may be arbitrary and the special value
+		"n/a" means that user space cannot accept any resume latency at
+		all for the given device.
 
 		Not all drivers support this attribute.  If it isn't supported,
 		it is not present.
