Cortex-A8 Power Mode; Overview; Cortex-A8 Power Mode Transition - Samsung S5PC110 Manual

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4.5 CORTEX-A8 POWER MODE

4.5.1 OVERVIEW

Cortex-A8 has its own four power modes, namely, RUN, STANDBY, L2RETENTION, and POWER-OFF.
In each power mode, power control of Cortex-A8 is done as follows:
•
In RUN mode, Core logic of Cortex-A8 is powered "ON" and clocked. The L2 cache of Cortex-A8 is power-on.
•
In STANDBY mode, Core logic of Cortex-A8 is powered "ON" and only wake-up logic is clocked. The L2
cache of Cortex-A8 is power-on.
•
In L2RETENTION mode, Core logic of Cortex-A8 is power-gated and L2 cache of Cortex-A8 enters retention
mode for data retention. Therefore, the data of L2 cache can be kept in this mode.
•
In POWER-OFF mode, all components of Cortex-A8 (that is, Core logic, L2 cache, ETM, and NEON) are all
power-gated.

4.5.2 CORTEX-A8 POWER MODE TRANSITION

For information on entry to and exit from STANDBY mode in IDLE mode, refer to
For information on entry to and exit from L2RETENTION and POWER-OFF in DEEP-IDLE mode, refer to
"DEEP-IDLE Mode".
In IDLE and STOP mode, Cortex-A8 enters STANDBY mode.
In DEEP-IDLE and DEEP-STOP mode, Cortex-A8 enters L2RETENTION or POWER-OFF mode depending on
the selection of L2 retention mode, that is, IDLE_CFG[27:26] for DEEP-IDLE mode, and STOP_CFG[27:26] for
DEEP-STOP mode.
In SLEEP mode, Cortex-A8 automatically enters POWER-OFF mode. Before entry into SLEEP mode, state of
Cortex-A8 must be saved in external memory.
shows the state transition diagram of Cortex-A8 power mode, and the relationship between System
Figure 4-3
power mode and Cortex-A8 power mode transition is summarized in
STANDBY, L2RETENTION, and POWER-OFF modes transition from RUN mode can be done in NORMAL
system power mode. STANDBY mode of Cortex-A8 can exist in IDLE and STOP system power modes.
L2RETENTION mode of Cortex-A8 can exist in DEEP-IDLE and DEEP-STOP system power mode. POWER-OFF
mode of Cortex-A8 can exist in DEEP-IDLE, DEEP-STOP, and SLEEP system power mode.
RUN mode transitions from STANDBY, L2RETENTION, and POWER-OFF can be done by wakeup sources. In
IDLE mode, internal interrupts, external interrupts, and RTC alarm can be wakeup sources. In DEEP-IDLE mode,
external interrupts, wakeup event, and RTC alarm can be wakeup sources. In STOP, and DEEP-STOP, external
interrupts, wakeup event, and RTC alarm can be wakeup sources.
4 POWER MANAGEMENT
4.3.3 "IDLE
Table 4-5.
Mode".
4.3.4
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