attached to "obio") on the IQ80310 and IQ80321. It makes more sense
to do it this way for this type of system (the goal being to encapsulate
as much information about the board as possible into one file).
not pre-load the chip's Tx buffer, but instead waits for the Tx Ready
interrupt to transmit the first chunk of data.
* On the IOP310, set COM_HW_NO_TXPRELOAD, rather than COM_HW_TXFIFO_DISABLE.
This solves the "UART hangs" problem on the Npwr in a nicer way (i.e. we
get to use the FIFO, whee). The COM_HW_NO_TXPRELOAD happens to match the
Linux 16550 driver's Tx algorithm, and the "UART hang" was never observed
on the Npwr running Linux.
Eventually, we might want to eliminate the COM_HW_NO_TXPRELOAD, and simply
always use its algorithm. But it should be tested on more 16x50 variants
before we do that.
Kudos to Valeriy Ushakov <uwe@netbsd.org> for pointing out this solution
(which also happens to fix the stray UART interrupt issue on the Krups
Javastation), and to Allen Briggs <briggs@netbsd.org> for experimenting
with various methods of fixing this.
