UART Problem: Receive fails until Transmit is done

I'm running uCLinux and have a device connected to the RX line of one
of my 16450-compatible UARTs.  When my device is initialized (through
another mechanism, not the serial port), the device sends about 16
bytes (at 9600-E-8-2) to the RX line, verified by an o'scope.

The problem I'm seeing is that a read() will not return the received
data until I transmit a byte.  I modified the serial driver to return
immediately in uart_tx_chars() to try get filling the FIFO out of the
picture.  Doing that and transmitting a byte in my application (the
byte did not transmit, as shown by the scope) allowed the read() to
work, whether the read() occurred 1 second later or 5 minutes later.

I first saw this with my app, but tip (I tap a key and the data shows
up) shows the same thing, so I don't think it's an initialization
problem.  I'm combing through the driver now, but does this condition
look familiar to anyone?  Any comments or suggestions would be
appreciated.

Thanks.