Texas Instruments OMAP5912 Reference Manual page 1396

USB Device Controller
Table 53. Receive Endpoint n Configuration Register (EPn_RX)
Bit Name
15 EPn_RX_VALID
14 EPn_RX_SIZE/DB
104 Universal Serial Bus (USB)
Description
The receive endpoint n valid bit must be set by the USB device controller
to allow receive 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: Receive endpoint n does not exist for this configuration.
1: Receive endpoint n is part of the device configuration.
Values after USB device controller hardware reset are low, after USB reset
is unchanged.
Receive non-ISO (or ISO) endpoint n double-buffer (DB).This bit is only for
non-ISO endpoints. For ISO endpoints, which are always double-buffered,
this bit is endpoint size MSB.
This bit must be set by the USB device controller to allow double buffering
for receive non-ISO endpoint n. This is used to reduce number of
transactions resulting in NAK handshake.
0: No double buffer for non-ISO receive endpoint n.
1: Double buffer used for non-ISO receive endpoint n.
Values after USB device controller hardware reset or USB reset are
unchanged (which means that values are unknown until first write access).
SPRU761A