SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
The DPLL_USB_OTG_SS accepts the functional clock, USB_OTG_SS_REF_CLK, on its CLKINP pin (REF_CLK input at USB3_PHY subsystem level) directly from the device PRCM, without involving any DPLLCTRL_USB_OTG_SS interactions. The USB_OTG_SS_REF_CLK is derived from SYS_CLK1. See Clock Domain Module Attributes in Power, Reset, and Clock Management.
If the CLKINP signal is lost for some time, the LOSSREF output signal, which serves as a feedback to DPLLCTRL_USB_OTG_SS, is asserted high. When CLKINP resumes, LOSSREF goes low (LOSSREF inactive state). The LOSSREF status signal can be software-monitored in the DPLLCTRL_USB_OTG_SS.PLL_STATUS[3] PLL_LOSSREF bit.
DPLLCTRL_USB_OTG_SS has no software or hardware mechanisms to control DPLL_USB_OTG_SS input clock (CLKINP).