UPSTREAM: cpuidle: remove the power_specified field in the driver

We realized that the power usage field is never filled and when it
is filled for tegra, the power_specified flag is not set causing all
of these values to be reset when the driver is initialized with
set_power_state().

However, the power_specified flag can be simply removed under the
assumption that the states are always backward sorted, which is the
case with the current code.

This change allows the menu governor select function and the
cpuidle_play_dead() to be simplified.  Moreover, the
set_power_states() function can removed as it does not make sense
any more.

Drop the power_specified flag from struct cpuidle_driver and make
the related changes as described above.

As a consequence, this also fixes the bug where on the dynamic
C-states system, the power fields are not initialized.

[rjw: Changelog]
References: https://bugzilla.kernel.org/show_bug.cgi?id=42870
References: https://bugzilla.kernel.org/show_bug.cgi?id=43349
References: https://lkml.org/lkml/2012/10/16/518
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit 8aef33a7cf40ca9da188e8578b2abe7267a38c52)

BUG=chromium-os:35320
TEST=Boot a ZGB on AC and unplug it afterwards. Run powertop and notice
how the device correctly goes down into C3.

Change-Id: If4f34246ce62d77094bf8f1a1718631a4b8e8030
Reviewed-on: https://gerrit.chromium.org/gerrit/42433
Reviewed-by: Sameer Nanda <snanda@chromium.org>
Commit-Queue: Julius Werner <jwerner@chromium.org>
Tested-by: Julius Werner <jwerner@chromium.org>

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 05c4ebf..2be11a9 100644 (file)
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -80,24 +80,15 @@ int cpuidle_play_dead(void)
 {
        struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
        struct cpuidle_driver *drv = cpuidle_get_driver();
-       int i, dead_state = -1;
-       int power_usage = -1;
+       int i;
 
        if (!drv)
                return -ENODEV;
 
        /* Find lowest-power state that supports long-term idle */
-       for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
-               struct cpuidle_state *s = &drv->states[i];
-
-               if (s->power_usage < power_usage && s->enter_dead) {
-                       power_usage = s->power_usage;
-                       dead_state = i;
-               }
-       }
-
-       if (dead_state != -1)
-               return drv->states[dead_state].enter_dead(dev, dead_state);
+       for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
+               if (drv->states[i].enter_dead)
+                       return drv->states[i].enter_dead(dev, i);
 
        return -ENODEV;
 }

diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index 40cd3f3..2265fcf 100644 (file)
--- a/drivers/cpuidle/driver.c
+++ b/drivers/cpuidle/driver.c
@@ -17,29 +17,6 @@
 static struct cpuidle_driver *cpuidle_curr_driver;
 DEFINE_SPINLOCK(cpuidle_driver_lock);
 
-static void __cpuidle_register_driver(struct cpuidle_driver *drv)
-{
-       int i;
-       /*
-        * cpuidle driver should set the drv->power_specified bit
-        * before registering if the driver provides
-        * power_usage numbers.
-        *
-        * If power_specified is not set,
-        * we fill in power_usage with decreasing values as the
-        * cpuidle code has an implicit assumption that state Cn
-        * uses less power than C(n-1).
-        *
-        * With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
-        * an power value of -1.  So we use -2, -3, etc, for other
-        * c-states.
-        */
-       if (!drv->power_specified) {
-               for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++)
-                       drv->states[i].power_usage = -1 - i;
-       }
-}
-
 
 /**
  * cpuidle_register_driver - registers a driver
@@ -58,7 +35,6 @@ int cpuidle_register_driver(struct cpuidle_driver *drv)
                spin_unlock(&cpuidle_driver_lock);
                return -EBUSY;
        }
-       __cpuidle_register_driver(drv);
        cpuidle_curr_driver = drv;
        spin_unlock(&cpuidle_driver_lock);
 

diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 0633575..2df35d1 100644 (file)
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -236,7 +236,6 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 {
        struct menu_device *data = &__get_cpu_var(menu_devices);
        int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
-       int power_usage = -1;
        int i;
        int multiplier;
        struct timespec t;
@@ -300,11 +299,8 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
                if (s->exit_latency * multiplier > data->predicted_us)
                        continue;
 
-               if (s->power_usage < power_usage) {
-                       power_usage = s->power_usage;
-                       data->last_state_idx = i;
-                       data->exit_us = s->exit_latency;
-               }
+               data->last_state_idx = i;
+               data->exit_us = s->exit_latency;
        }
 
        return data->last_state_idx;

diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 6c26a3d..10f74f2 100644 (file)
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -124,9 +124,9 @@ struct cpuidle_driver {
        const char              *name;
        struct module           *owner;
 
-       unsigned int            power_specified:1;
        /* set to 1 to use the core cpuidle time keeping (for all states). */
        unsigned int            en_core_tk_irqen:1;
+       /* states array must be ordered in decreasing power consumption */
        struct cpuidle_state    states[CPUIDLE_STATE_MAX];
        int                     state_count;
        int                     safe_state_index;