USB Host Controller Reset and Clock Control
14-117
Universal Serial Bus Host
14.9.5 USB Host Controller Power Management
Power management of the OMAP5910 USB host controller is limited to disab-
ling the clock to the USB host controller using the MOD_CONF_CTRL_0 regis-
ter CONF_MOD_USB_HOST_HHC_UHOST_EN_R bit. When this bit is 0,
the USB host controller clocks are disabled and the USB host controller is held
in reset. The USB signal multiplexing controlled by CONF_MOD_USB_HOST
_HMC_MODE_R is not affected, so a CONF_MOD_USB_HOST_HMC
_MODE_R setting that multiplexes USB function controller and/or UART1
signals to OMAP5910 top-level multiplexing can still make use of the USB
function controller and/or UART1.
When the OMAP5910 host controller’s 48-MHz clock is disabled, all USB host
controller OHCI registers and the HostUEAddr, HostUEStatus, Host-
TimeoutCtrl, and HostRevision registers are inaccessible.
14.9.6 Local Bus Clock
Proper operation of the USB host controller requires that the local bus clock
be enabled. For details, see Section 14.7.11, Local Bus Initialization.