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Subject[PATCH] pm_qos: Add QoS param, minimum system bus frequency
Date
From: Praveen Chidambaram <pchidamb@quicinc.com>

In some systems, the system bus speed can be varied, usually
based on the current CPU frequency. However, various device
drivers and/or applications may need a faster system bus for I/O
even though the CPU itself may be idle.

Signed-off-by: Praveen Chidambaram <pchidamb@quicinc.com>
Signed-off-by: David Brown <davidb@quicinc.com>
Signed-off-by: Daniel Walker <dwalker@codeaurora.org>
---
include/linux/pm_qos_params.h | 3 ++-
kernel/pm_qos_params.c | 32 +++++++++++++++++++++++++-------
2 files changed, 27 insertions(+), 8 deletions(-)
diff --git a/include/linux/pm_qos_params.h b/include/linux/pm_qos_params.h
index d74f75e..091c13c 100644
--- a/include/linux/pm_qos_params.h
+++ b/include/linux/pm_qos_params.h
@@ -10,8 +10,9 @@
#define PM_QOS_CPU_DMA_LATENCY 1
#define PM_QOS_NETWORK_LATENCY 2
#define PM_QOS_NETWORK_THROUGHPUT 3
+#define PM_QOS_SYSTEM_BUS_FREQ 4

-#define PM_QOS_NUM_CLASSES 4
+#define PM_QOS_NUM_CLASSES 5
#define PM_QOS_DEFAULT_VALUE -1

int pm_qos_add_requirement(int qos, char *name, s32 value);
diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c
index 3db49b9..8576f40 100644
--- a/kernel/pm_qos_params.c
+++ b/kernel/pm_qos_params.c
@@ -102,12 +102,24 @@ static struct pm_qos_object network_throughput_pm_qos = {
.comparitor = max_compare
};

+static BLOCKING_NOTIFIER_HEAD(system_bus_freq_notifier);
+static struct pm_qos_object system_bus_freq_pm_qos = {
+ .requirements =
+ {LIST_HEAD_INIT(system_bus_freq_pm_qos.requirements.list)},
+ .notifiers = &system_bus_freq_notifier,
+ .name = "system_bus_freq",
+ .default_value = 0,
+ .target_value = ATOMIC_INIT(0),
+ .comparitor = max_compare
+};
+

-static struct pm_qos_object *pm_qos_array[] = {
- &null_pm_qos,
- &cpu_dma_pm_qos,
- &network_lat_pm_qos,
- &network_throughput_pm_qos
+static struct pm_qos_object *pm_qos_array[PM_QOS_NUM_CLASSES] = {
+ [PM_QOS_RESERVED] = &null_pm_qos,
+ [PM_QOS_CPU_DMA_LATENCY] = &cpu_dma_pm_qos,
+ [PM_QOS_NETWORK_LATENCY] = &network_lat_pm_qos,
+ [PM_QOS_NETWORK_THROUGHPUT] = &network_throughput_pm_qos,
+ [PM_QOS_SYSTEM_BUS_FREQ] = &system_bus_freq_pm_qos,
};

static DEFINE_SPINLOCK(pm_qos_lock);
@@ -313,7 +325,7 @@ EXPORT_SYMBOL_GPL(pm_qos_remove_requirement);
* will register the notifier into a notification chain that gets called
* upon changes to the pm_qos_class target value.
*/
- int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
+int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
{
int retval;

@@ -409,9 +421,15 @@ static int __init pm_qos_power_init(void)
return ret;
}
ret = register_pm_qos_misc(&network_throughput_pm_qos);
- if (ret < 0)
+ if (ret < 0) {
printk(KERN_ERR
"pm_qos_param: network_throughput setup failed\n");
+ return ret;
+ }
+ ret = register_pm_qos_misc(&system_bus_freq_pm_qos);
+ if (ret < 0)
+ printk(KERN_ERR
+ "pm_qos_param: system_bus_freq setup failed\n");

return ret;
}
--
1.6.3.3


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