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| author | Jean Pihet <jean.pihet@newoldbits.com> | 2012-06-01 17:11:07 +0200 |
|---|---|---|
| committer | Kevin Hilman <khilman@ti.com> | 2012-06-25 11:24:24 -0700 |
| commit | 13d65c897e93dfeaed6fe28233559239f9676164 (patch) | |
| tree | 0e68226def4d9b927ef44abbf6ac742a42680496 | |
| parent | 063a5d011698950c86a01044394105605556e92c (diff) | |
| download | linux-13d65c897e93dfeaed6fe28233559239f9676164.tar.gz linux-13d65c897e93dfeaed6fe28233559239f9676164.tar.bz2 linux-13d65c897e93dfeaed6fe28233559239f9676164.zip | |
ARM: OMAP3: PM: cpuidle: optimize the PER latency in C1 state
One of the main contributors of the low power code latency is
the PER power domain. To optimize the high-performance and
low-latency C1 state, prevent any PER state which is lower
than the CORE state in C1.
Reported and suggested by Kevin Hilman.
Reported-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Jean Pihet <j-pihet@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>
| -rw-r--r-- | arch/arm/mach-omap2/cpuidle34xx.c | 41 |
1 files changed, 22 insertions, 19 deletions
diff --git a/arch/arm/mach-omap2/cpuidle34xx.c b/arch/arm/mach-omap2/cpuidle34xx.c index f619a928f01e..2e2f1c6f0f0b 100644 --- a/arch/arm/mach-omap2/cpuidle34xx.c +++ b/arch/arm/mach-omap2/cpuidle34xx.c @@ -222,23 +222,22 @@ static int next_valid_state(struct cpuidle_device *dev, * the device to the specified or a safer state. */ static int omap3_enter_idle_bm(struct cpuidle_device *dev, - struct cpuidle_driver *drv, + struct cpuidle_driver *drv, int index) { int new_state_idx; - u32 core_next_state, per_next_state = 0, per_saved_state = 0, cam_state; + u32 core_next_state, per_next_state = 0, per_saved_state = 0; struct omap3_idle_statedata *cx; int ret; /* - * Prevent idle completely if CAM is active. + * Use only C1 if CAM is active. * CAM does not have wakeup capability in OMAP3. */ - cam_state = pwrdm_read_pwrst(cam_pd); - if (cam_state == PWRDM_POWER_ON) { + if (pwrdm_read_pwrst(cam_pd) == PWRDM_POWER_ON) new_state_idx = drv->safe_state_index; - goto select_state; - } + else + new_state_idx = next_valid_state(dev, drv, index); /* * FIXME: we currently manage device-specific idle states @@ -248,24 +247,28 @@ static int omap3_enter_idle_bm(struct cpuidle_device *dev, * its own code. */ - /* - * Prevent PER off if CORE is not in retention or off as this - * would disable PER wakeups completely. - */ - cx = &omap3_idle_data[index]; + /* Program PER state */ + cx = &omap3_idle_data[new_state_idx]; core_next_state = cx->core_state; per_next_state = per_saved_state = pwrdm_read_next_pwrst(per_pd); - if ((per_next_state == PWRDM_POWER_OFF) && - (core_next_state > PWRDM_POWER_RET)) - per_next_state = PWRDM_POWER_RET; + if (new_state_idx == 0) { + /* In C1 do not allow PER state lower than CORE state */ + if (per_next_state < core_next_state) + per_next_state = core_next_state; + } else { + /* + * Prevent PER OFF if CORE is not in RETention or OFF as this + * would disable PER wakeups completely. + */ + if ((per_next_state == PWRDM_POWER_OFF) && + (core_next_state > PWRDM_POWER_RET)) + per_next_state = PWRDM_POWER_RET; + } /* Are we changing PER target state? */ if (per_next_state != per_saved_state) pwrdm_set_next_pwrst(per_pd, per_next_state); - new_state_idx = next_valid_state(dev, drv, index); - -select_state: ret = omap3_enter_idle(dev, drv, new_state_idx); /* Restore original PER state if it was modified */ @@ -282,7 +285,7 @@ struct cpuidle_driver omap3_idle_driver = { .owner = THIS_MODULE, .states = { { - .enter = omap3_enter_idle, + .enter = omap3_enter_idle_bm, .exit_latency = 2 + 2, .target_residency = 5, .flags = CPUIDLE_FLAG_TIME_VALID, |