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PRCM Basic Programming Model
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NOTE:
The interface clock ensures proper communication between any module and the
interconnect (L3 or L4), in most cases supplying the module interface and registers.
3.6.2.4.4 CM_AUTOIDLE_ <domain_name> (Autoidle Register)
The autoidle register holds an AUTOIDLE bit per module that belongs to the related power domain. Each
AUTOIDLE bit enables/disables automatic (hardware) gating of a module interface clock.
When AUTOIDLE and ICLKEN are set for a module, the module interface clock is managed automatically
(that is, by hardware control) according to the power domain clock activity; for example, stopped before a
power domain sleep transition and reenabled on wakeup.
lists the possible autoidle settings for
the interface clock.
Table 3-89. Interface Clock Autoidle Settings
CM_AUTOIDLE.AUTO_<module>
CM_ICLKEN.EN_<module>
Interface Clock
0
0
Disabled
0
1
Enabled
1
0
Disabled
1
1
Automatic enabling/disabling
The device has the following autoidle control registers:
•
and
: CORE domain peripherals set
•
: Camera subsystem
•
: DSS subsystem
•
: PER domain peripherals set
•
: WKUP domain peripherals set
•
: HS USB Host subsystem
NOTE:
For SmartReflex1 and 2, IVA2.2, and GFX modules, the automatic idle mode is always
enabled, and is not software-controllable.
3.6.2.4.5 CM_IDLEST_ <domain_name> (Idle-Status Register)
The idle-status register allows checking whether a target module is in idle mode or if an initiator module is
in standby mode. Software must not access a target module in idle mode. A target access in this state can
lead to an error.
The idle mode of any module can depend on the configuration of the CM_FCLKEN_<domain_name> and
CM_ICLKEN_<domain_name> registers, or may be controlled automatically by hardware, depending on
the configuration of the CM_AUTOIDLE_<domain_name> registers.
In the case of IVA2.2 subsystem, standby mode is reached after the IVA2.2 processor has performed its
idle instruction.
The device has the following idle status registers:
•
: MPU subsystem
•
and
: CORE domain peripherals set
•
: Camera subsystem
•
: DSS
•
: Peripheral domain peripherals set
•
: NEON subsystem
•
: IVA2.2 subsystem
•
SGX subsystem
•
: WKUP domain peripherals set
•
: HS USB Host subsystem
408
Power, Reset, and Clock Management
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated