PM QOS update

This patch changes the string based list management to a handle base
implementation to help with the hot path use of pm-qos, it also renames
much of the API to use "request" as opposed to "requirement" that was
used in the initial implementation.  I did this because request more
accurately represents what it actually does.

Also, I added a string based ABI for users wanting to use a string
interface.  So if the user writes 0xDDDDDDDD formatted hex it will be
accepted by the interface.  (someone asked me for it and I don't think
it hurts anything.)

This patch updates some documentation input I got from Randy.
Signed-off-by: markgross <mgross@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

Documentation/power/pm_qos_interface.txt

@@ -18,44 +18,46 @@ and pm_qos_params.h.  This is done because having the available parameters
 being runtime configurable or changeable from a driver was seen as too easy to
 abuse.
 
-For each parameter a list of performance requirements is maintained along with
+For each parameter a list of performance requests is maintained along with
 an aggregated target value.  The aggregated target value is updated with
-changes to the requirement list or elements of the list.  Typically the
-aggregated target value is simply the max or min of the requirement values held
+changes to the request list or elements of the list.  Typically the
+aggregated target value is simply the max or min of the request values held
 in the parameter list elements.
 
 From kernel mode the use of this interface is simple:
-pm_qos_add_requirement(param_id, name, target_value):
-Will insert a named element in the list for that identified PM_QOS parameter
-with the target value.  Upon change to this list the new target is recomputed
-and any registered notifiers are called only if the target value is now
-different.
 
-pm_qos_update_requirement(param_id, name, new_target_value):
-Will search the list identified by the param_id for the named list element and
-then update its target value, calling the notification tree if the aggregated
-target is changed.  with that name is already registered.
+handle = pm_qos_add_request(param_class, target_value):
+Will insert an element into the list for that identified PM_QOS class with the
+target value.  Upon change to this list the new target is recomputed and any
+registered notifiers are called only if the target value is now different.
+Clients of pm_qos need to save the returned handle.
 
-pm_qos_remove_requirement(param_id, name):
-Will search the identified list for the named element and remove it, after
-removal it will update the aggregate target and call the notification tree if
-the target was changed as a result of removing the named requirement.
+void pm_qos_update_request(handle, new_target_value):
+Will update the list element pointed to by the handle with the new target value
+and recompute the new aggregated target, calling the notification tree if the
+target is changed.
+
+void pm_qos_remove_request(handle):
+Will remove the element.  After removal it will update the aggregate target and
+call the notification tree if the target was changed as a result of removing
+the request.
 
 
 From user mode:
-Only processes can register a pm_qos requirement.  To provide for automatic
-cleanup for process the interface requires the process to register its
-parameter requirements in the following way:
+Only processes can register a pm_qos request.  To provide for automatic
+cleanup of a process, the interface requires the process to register its
+parameter requests in the following way:
 
 To register the default pm_qos target for the specific parameter, the process
 must open one of /dev/[cpu_dma_latency, network_latency, network_throughput]
 
 As long as the device node is held open that process has a registered
-requirement on the parameter.  The name of the requirement is "process_<PID>"
-derived from the current->pid from within the open system call.
+request on the parameter.
 
-To change the requested target value the process needs to write a s32 value to
-the open device node.  This translates to a pm_qos_update_requirement call.
+To change the requested target value the process needs to write an s32 value to
+the open device node.  Alternatively the user mode program could write a hex
+string for the value using 10 char long format e.g. "0x12345678".  This
+translates to a pm_qos_update_request call.
 
 To remove the user mode request for a target value simply close the device
 node.

drivers/acpi/processor_idle.c

@@ -698,7 +698,7 @@ static int acpi_processor_power_seq_show(struct seq_file *seq, void *offset)
 		   "max_cstate:              C%d\n"
 		   "maximum allowed latency: %d usec\n",
 		   pr->power.state ? pr->power.state - pr->power.states : 0,
-		   max_cstate, pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY));
+		   max_cstate, pm_qos_request(PM_QOS_CPU_DMA_LATENCY));
 
 	seq_puts(seq, "states:\n");
 

drivers/cpuidle/governors/ladder.c

@@ -67,7 +67,7 @@ static int ladder_select_state(struct cpuidle_device *dev)
 	struct ladder_device *ldev = &__get_cpu_var(ladder_devices);
 	struct ladder_device_state *last_state;
 	int last_residency, last_idx = ldev->last_state_idx;
-	int latency_req = pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY);
+	int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
 
 	/* Special case when user has set very strict latency requirement */
 	if (unlikely(latency_req == 0)) {

drivers/cpuidle/governors/menu.c

@@ -182,7 +182,7 @@ static u64 div_round64(u64 dividend, u32 divisor)
 static int menu_select(struct cpuidle_device *dev)
 {
 	struct menu_device *data = &__get_cpu_var(menu_devices);
-	int latency_req = pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY);
+	int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
 	int i;
 	int multiplier;
 

drivers/net/e1000e/netdev.c

@@ -2524,11 +2524,11 @@ static void e1000_configure_rx(struct e1000_adapter *adapter)
 			 * excessive C-state transition latencies result in
 			 * dropped transactions.
 			 */
-			pm_qos_update_requirement(PM_QOS_CPU_DMA_LATENCY,
-						  adapter->netdev->name, 55);
+			pm_qos_update_request(
+				adapter->netdev->pm_qos_req, 55);
 		} else {
-			pm_qos_update_requirement(PM_QOS_CPU_DMA_LATENCY,
-						  adapter->netdev->name,
+			pm_qos_update_request(
+				adapter->netdev->pm_qos_req,
 				PM_QOS_DEFAULT_VALUE);
 		}
 	}
@@ -2824,8 +2824,8 @@ int e1000e_up(struct e1000_adapter *adapter)
 
 	/* DMA latency requirement to workaround early-receive/jumbo issue */
 	if (adapter->flags & FLAG_HAS_ERT)
-		pm_qos_add_requirement(PM_QOS_CPU_DMA_LATENCY,
-		                       adapter->netdev->name,
+		adapter->netdev->pm_qos_req =
+			pm_qos_add_request(PM_QOS_CPU_DMA_LATENCY,
 				       PM_QOS_DEFAULT_VALUE);
 
 	/* hardware has been reset, we need to reload some things */
@@ -2887,9 +2887,11 @@ void e1000e_down(struct e1000_adapter *adapter)
 	e1000_clean_tx_ring(adapter);
 	e1000_clean_rx_ring(adapter);
 
-	if (adapter->flags & FLAG_HAS_ERT)
-		pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY,
-		                          adapter->netdev->name);
+	if (adapter->flags & FLAG_HAS_ERT) {
+		pm_qos_remove_request(
+			      adapter->netdev->pm_qos_req);
+		adapter->netdev->pm_qos_req = NULL;
+	}
 
 	/*
 	 * TODO: for power management, we could drop the link and

drivers/net/igbvf/netdev.c

@@ -48,6 +48,7 @@
 #define DRV_VERSION "1.0.0-k0"
 char igbvf_driver_name[] = "igbvf";
 const char igbvf_driver_version[] = DRV_VERSION;
+struct pm_qos_request_list *igbvf_driver_pm_qos_req;
 static const char igbvf_driver_string[] =
 				"Intel(R) Virtual Function Network Driver";
 static const char igbvf_copyright[] = "Copyright (c) 2009 Intel Corporation.";
@@ -2899,7 +2900,7 @@ static int __init igbvf_init_module(void)
 	printk(KERN_INFO "%s\n", igbvf_copyright);
 
 	ret = pci_register_driver(&igbvf_driver);
-	pm_qos_add_requirement(PM_QOS_CPU_DMA_LATENCY, igbvf_driver_name,
+	igbvf_driver_pm_qos_req = pm_qos_add_request(PM_QOS_CPU_DMA_LATENCY,
 	                       PM_QOS_DEFAULT_VALUE);
 
 	return ret;
@@ -2915,7 +2916,8 @@ module_init(igbvf_init_module);
 static void __exit igbvf_exit_module(void)
 {
 	pci_unregister_driver(&igbvf_driver);
-	pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY, igbvf_driver_name);
+	pm_qos_remove_request(igbvf_driver_pm_qos_req);
+	igbvf_driver_pm_qos_req = NULL;
 }
 module_exit(igbvf_exit_module);
 

drivers/net/wireless/ipw2x00/ipw2100.c

@@ -174,6 +174,8 @@ that only one external action is invoked at a time.
 #define DRV_DESCRIPTION	"Intel(R) PRO/Wireless 2100 Network Driver"
 #define DRV_COPYRIGHT	"Copyright(c) 2003-2006 Intel Corporation"
 
+struct pm_qos_request_list *ipw2100_pm_qos_req;
+
 /* Debugging stuff */
 #ifdef CONFIG_IPW2100_DEBUG
 #define IPW2100_RX_DEBUG	/* Reception debugging */
@@ -1739,7 +1741,7 @@ static int ipw2100_up(struct ipw2100_priv *priv, int deferred)
 	/* the ipw2100 hardware really doesn't want power management delays
 	 * longer than 175usec
 	 */
-	pm_qos_update_requirement(PM_QOS_CPU_DMA_LATENCY, "ipw2100", 175);
+	pm_qos_update_request(ipw2100_pm_qos_req, 175);
 
 	/* If the interrupt is enabled, turn it off... */
 	spin_lock_irqsave(&priv->low_lock, flags);
@@ -1887,8 +1889,7 @@ static void ipw2100_down(struct ipw2100_priv *priv)
 	ipw2100_disable_interrupts(priv);
 	spin_unlock_irqrestore(&priv->low_lock, flags);
 
-	pm_qos_update_requirement(PM_QOS_CPU_DMA_LATENCY, "ipw2100",
-			PM_QOS_DEFAULT_VALUE);
+	pm_qos_update_request(ipw2100_pm_qos_req, PM_QOS_DEFAULT_VALUE);
 
 	/* We have to signal any supplicant if we are disassociating */
 	if (associated)
@@ -6669,7 +6670,7 @@ static int __init ipw2100_init(void)
 	if (ret)
 		goto out;
 
-	pm_qos_add_requirement(PM_QOS_CPU_DMA_LATENCY, "ipw2100",
+	ipw2100_pm_qos_req = pm_qos_add_request(PM_QOS_CPU_DMA_LATENCY,
 			PM_QOS_DEFAULT_VALUE);
 #ifdef CONFIG_IPW2100_DEBUG
 	ipw2100_debug_level = debug;
@@ -6692,7 +6693,7 @@ static void __exit ipw2100_exit(void)
 			   &driver_attr_debug_level);
 #endif
 	pci_unregister_driver(&ipw2100_pci_driver);
-	pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY, "ipw2100");
+	pm_qos_remove_request(ipw2100_pm_qos_req);
 }
 
 module_init(ipw2100_init);

include/linux/netdevice.h

@@ -31,6 +31,7 @@
 #include <linux/if_link.h>
 
 #ifdef __KERNEL__
+#include <linux/pm_qos_params.h>
 #include <linux/timer.h>
 #include <linux/delay.h>
 #include <linux/mm.h>
@@ -711,6 +712,9 @@ struct net_device {
 	 * the interface.
 	 */
 	char			name[IFNAMSIZ];
+
+	struct pm_qos_request_list *pm_qos_req;
+
 	/* device name hash chain */
 	struct hlist_node	name_hlist;
 	/* snmp alias */

include/linux/pm_qos_params.h

@@ -14,12 +14,14 @@
 #define PM_QOS_NUM_CLASSES 4
 #define PM_QOS_DEFAULT_VALUE -1
 
-int pm_qos_add_requirement(int qos, char *name, s32 value);
-int pm_qos_update_requirement(int qos, char *name, s32 new_value);
-void pm_qos_remove_requirement(int qos, char *name);
+struct pm_qos_request_list;
 
-int pm_qos_requirement(int qos);
+struct pm_qos_request_list *pm_qos_add_request(int pm_qos_class, s32 value);
+void pm_qos_update_request(struct pm_qos_request_list *pm_qos_req,
+		s32 new_value);
+void pm_qos_remove_request(struct pm_qos_request_list *pm_qos_req);
 
-int pm_qos_add_notifier(int qos, struct notifier_block *notifier);
-int pm_qos_remove_notifier(int qos, struct notifier_block *notifier);
+int pm_qos_request(int pm_qos_class);
+int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier);
+int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier);
 

include/sound/pcm.h

@@ -29,6 +29,7 @@
 #include <linux/poll.h>
 #include <linux/mm.h>
 #include <linux/bitops.h>
+#include <linux/pm_qos_params.h>
 
 #define snd_pcm_substream_chip(substream) ((substream)->private_data)
 #define snd_pcm_chip(pcm) ((pcm)->private_data)
@@ -365,7 +366,7 @@ struct snd_pcm_substream {
 	int number;
 	char name[32];			/* substream name */
 	int stream;			/* stream (direction) */
-	char latency_id[20];		/* latency identifier */
+	struct pm_qos_request_list *latency_pm_qos_req; /* pm_qos request */
 	size_t buffer_bytes_max;	/* limit ring buffer size */
 	struct snd_dma_buffer dma_buffer;
 	unsigned int dma_buf_id;

net/mac80211/mlme.c

@@ -495,7 +495,7 @@ void ieee80211_recalc_ps(struct ieee80211_local *local, s32 latency)
 		s32 beaconint_us;
 
 		if (latency < 0)
-			latency = pm_qos_requirement(PM_QOS_NETWORK_LATENCY);
+			latency = pm_qos_request(PM_QOS_NETWORK_LATENCY);
 
 		beaconint_us = ieee80211_tu_to_usec(
 					found->vif.bss_conf.beacon_int);

sound/core/pcm.c

@@ -648,9 +648,6 @@ int snd_pcm_new_stream(struct snd_pcm *pcm, int stream, int substream_count)
 		substream->number = idx;
 		substream->stream = stream;
 		sprintf(substream->name, "subdevice #%i", idx);
-		snprintf(substream->latency_id, sizeof(substream->latency_id),
-			 "ALSA-PCM%d-%d%c%d", pcm->card->number, pcm->device,
-			 (stream ? 'c' : 'p'), idx);
 		substream->buffer_bytes_max = UINT_MAX;
 		if (prev == NULL)
 			pstr->substream = substream;

sound/core/pcm_native.c

@@ -481,11 +481,13 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
 	snd_pcm_timer_resolution_change(substream);
 	runtime->status->state = SNDRV_PCM_STATE_SETUP;
 
-	pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY,
-				substream->latency_id);
+	if (substream->latency_pm_qos_req) {
+		pm_qos_remove_request(substream->latency_pm_qos_req);
+		substream->latency_pm_qos_req = NULL;
+	}
 	if ((usecs = period_to_usecs(runtime)) >= 0)
-		pm_qos_add_requirement(PM_QOS_CPU_DMA_LATENCY,
-					substream->latency_id, usecs);
+		substream->latency_pm_qos_req = pm_qos_add_request(
+					PM_QOS_CPU_DMA_LATENCY, usecs);
 	return 0;
  _error:
 	/* hardware might be unuseable from this time,
@@ -540,8 +542,8 @@ static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
 	if (substream->ops->hw_free)
 		result = substream->ops->hw_free(substream);
 	runtime->status->state = SNDRV_PCM_STATE_OPEN;
-	pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY,
-		substream->latency_id);
+	pm_qos_remove_request(substream->latency_pm_qos_req);
+	substream->latency_pm_qos_req = NULL;
 	return result;
 }