SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
At the PRCM module level, when all conditions to shut off the functional or interface output clocks of the PRCM module are met (see Clock Domain-Level Clock Management), the PRCM module automatically launches a hardware handshake protocol to ensure the GP timer is ready to have its clocks switched off. Namely, the PRCM module asserts an IDLE request to the GP timer.
Although this handshake is a hardware function and is out of software control, the way the GP timer acknowledges the PRCM IDLE request is configurable through the TIOCP_CFG[3:2] IDLEMODE bit field.
Table 22-6 lists the IDLEMODE settings and the related acknowledgment modes.
IDLEMODE Value | Selected Mode | Description |
---|---|---|
00 | Force-idle | The GP timer unconditionally acknowledges the IDLE request from the PRCM module, regardless of its internal operations. This mode must be used carefully, because it does not prevent the loss of data when the clock is switched off. |
01 | No-idle | The GP timer never acknowledges an IDLE request from the PRCM module. This mode is safe from a module point of view, because it ensures that the clocks remain active. It is not efficient from a power-saving perspective, however, because it does not allow the PRCM output clock to be shut off and thus the power domain to be set to a lower power state. |
10 | Smart-idle | The GP timer acknowledges the IDLE request, basing its decision on its internal activity. The acknowledge signal is asserted only when all pending transactions and IRQ requests are treated. This is the best approach to efficient system power management. |
11 | Smart-idleWakeup | The module behaves like in Smart-idle mode, with the exception, that it can issue a wake-up request in sleep mode, if the functional clock is not cut off. |