Texas Instruments OMAP5912 Reference Manual page 1399

Table 54. Transmit Endpoint n Configuration Register (EPn_TX)
Bit Name
15 EPn_TX_VALID
14 EPn_TX_SIZE/Db
13:12 EPn_TX_SIZE
SPRU761A
Description
The transmit endpoint n valid bit must be set by the USB device controller
to allow transmit endpoint n to be used for USB transfers as part of the
device configuration. If not set, all transactions to this endpoint are ignored
by the core.
0: Transmit endpoint n does not exist for this configuration.
1: Transmit endpoint n is part of the device configuration.
Values after USB device controller hardware reset are low, after USB reset
is unchanged.
Transmit non-ISO (or ISO) endpoint n double buffer. This bit is only for
non-ISO endpoints used in DMA mode. For ISO endpoints, which are
always double buffered, this bit is endpoint size MSB.
For non-ISO endpoints that are not used in a DMA transfer, double
buffering is not provided.This bit must be set by the USB device controller
to allow double buffering for transmit non-ISO endpoint n, when used in a
DMA transfer. This is used to reduce the number of transactions resulting
in NAK handshake.
0: No double buffer for non-ISO transmit endpoint n.
1: Double buffer used for non-ISO transmit endpoint n.
Values after MPU or USB reset is unchanged.
Or transmit ISO endpoint n size[2]
Transmit endpoint n size
USB Device Controller
Universal Serial Bus (USB) 107