PM / QoS: Add type to dev_pm_qos_add_ancestor_request() arguments

Rework dev_pm_qos_add_ancestor_request() so that device PM QoS type
is passed to it as the third argument and make it support the
DEV_PM_QOS_LATENCY_TOLERANCE device PM QoS type (in addition to
DEV_PM_QOS_RESUME_LATENCY).

That will allow the drivers of devices without latency tolerance
hardware support to use their ancestors having it as proxies for
their latency tolerance requirements.

Signed-off-by: Rafael J. Wysocki <[e-mail]>

Documentation/power/pm_qos_interface.txt

···
 	PM_QOS_FLAGS_UNDEFINED: The device's PM QoS structure has not been
 			initialized or the list of requests is empty.
 
-int dev_pm_qos_add_ancestor_request(dev, handle, value)
+int dev_pm_qos_add_ancestor_request(dev, handle, type, value)
 Add a PM QoS request for the first direct ancestor of the given device whose
-power.ignore_children flag is unset.
+power.ignore_children flag is unset (for DEV_PM_QOS_RESUME_LATENCY requests)
+or whose power.set_latency_tolerance callback pointer is not NULL (for
+DEV_PM_QOS_LATENCY_TOLERANCE requests).
 
 int dev_pm_qos_expose_latency_limit(device, value)
 Add a request to the device's PM QoS list of resume latency constraints and

drivers/base/power/qos.c

···
  * dev_pm_qos_add_ancestor_request - Add PM QoS request for device's ancestor.
  * @dev: Device whose ancestor to add the request for.
  * @req: Pointer to the preallocated handle.
+ * @type: Type of the request.
  * @value: Constraint latency value.
  */
 int dev_pm_qos_add_ancestor_request(struct device *dev,
-				    struct dev_pm_qos_request *req, s32 value)
+				    struct dev_pm_qos_request *req,
+				    enum dev_pm_qos_req_type type, s32 value)
 {
 	struct device *ancestor = dev->parent;
 	int ret = -ENODEV;
 
-	while (ancestor && !ancestor->power.ignore_children)
-		ancestor = ancestor->parent;
+	switch (type) {
+	case DEV_PM_QOS_RESUME_LATENCY:
+		while (ancestor && !ancestor->power.ignore_children)
+			ancestor = ancestor->parent;
 
+		break;
+	case DEV_PM_QOS_LATENCY_TOLERANCE:
+		while (ancestor && !ancestor->power.set_latency_tolerance)
+			ancestor = ancestor->parent;
+
+		break;
+	default:
+		ancestor = NULL;
+	}
 	if (ancestor)
-		ret = dev_pm_qos_add_request(ancestor, req,
-					     DEV_PM_QOS_RESUME_LATENCY, value);
+		ret = dev_pm_qos_add_request(ancestor, req, type, value);
 
 	if (ret < 0)
 		req->dev = NULL;

drivers/input/touchscreen/st1232.c

···
 	} else if (!ts->low_latency_req.dev) {
 		/* First contact, request 100 us latency. */
 		dev_pm_qos_add_ancestor_request(&ts->client->dev,
-						&ts->low_latency_req, 100);
+						&ts->low_latency_req,
+						DEV_PM_QOS_RESUME_LATENCY, 100);
 	}
 
 	/* SYN_REPORT */

include/linux/pm_qos.h

···
 void dev_pm_qos_constraints_init(struct device *dev);
 void dev_pm_qos_constraints_destroy(struct device *dev);
 int dev_pm_qos_add_ancestor_request(struct device *dev,
-				    struct dev_pm_qos_request *req, s32 value);
+				    struct dev_pm_qos_request *req,
+				    enum dev_pm_qos_req_type type, s32 value);
 #else
 static inline enum pm_qos_flags_status __dev_pm_qos_flags(struct device *dev,
 							  s32 mask)
···
 	dev->power.power_state = PMSG_INVALID;
 }
 static inline int dev_pm_qos_add_ancestor_request(struct device *dev,
-				    struct dev_pm_qos_request *req, s32 value)
+						  struct dev_pm_qos_request *req,
+						  enum dev_pm_qos_req_type type,
+						  s32 value)
 			{ return 0; }
 #endif