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2.2.3
HMC_MODE and Top-Level Pin Multiplexing and OHCI Registers
2.2.4
No Ownership Change Interrupt
2.3
OMAP5912 Implementation of OHCI Specification for USB
2.3.1
Isochronous Transmit Descriptor (TD) OFFSETX/PSWX Values
2.3.2
OMAP5912 USB Host Controller Endpoint Descriptor (ED) List Head
Pointers
SPRU761A
Users
can
use
software
implementation-specific control mechanisms to report port overcurrent
information to the USB host controller driver.
The USB signal multiplexing modes selected by HMC_MODE provide
selections where 0, 1, 2, or 3 USB host controller ports can be brought to
OMAP5912 pins. The OHCI RHDESCRIPTORA register always reports three
available USB host ports, regardless of the HMC_MODE setting (see
Table 20) or top-level pin multiplexing settings. When the HMC_MODE setting
disables a USB host controller port, the USB host controller sees that port as
unattached.
When OMAP5912 top-level pin multiplexing configures a pin for functionality
other than the USB, the USB host controller is disconnected from that pin and
that pin does not affect the USB host controller.
The OMAP5912 USB host controller does not implement the OHCI ownership
change interrupt.
The OMAP5912 USB host controller implements the OHCI Specification for
USB optional feature of checking isochronous OFFSETX/PSWX values. If
either OFFSETX or OFFSET(X+1) does not have a condition code of Not
Accessed, or if the OFFSET(X+1) value is not greater than or equal to
OFFSETX, then an unrecoverable error is reported. Unrecoverable errors
issued for these reasons do not cause an update of the HOSTUEADDR,
HOSTUESTATUS, or HOSTTIMEOUTCTRL registers.
The OHCI Specification for USB provides a specific sequence of operations
for the host controller driver to perform when setting up the host controller.
Failure to follow that sequence can result in malfunction. As a specific
example, the HCCONTROLHEADED and HCBULKHEADED pointer
registers and the 32 HCCAINTERRUPTTABLE pointers must all point to valid
physical addresses of valid endpoint descriptors.
monitoring
of
GPIO
Universal Serial Bus (USB)
USB Host Controller
pins
or
other
23
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