I've built a PC/104 board with two 16550 UARTS on it, but the UARTS
are not being recognized correctly on a cold boot. If I warm boot
(meaning I press the reset button, do a shutdown -r now, or stop my
watchdog) everything gets recognized fine.
On a warm bootup, the board displays the following on the console...
...
Off-board serial at /dev/tts/2 0x3e8 COM3
Off-board serial at /dev/tts/3 0x2e8 COM4
...
On a cold bootup, sometimes I get one device, sometimes the other...
The missing UART doesn't show up in devfs. Again, a warm bootup has
worked perfectly every time so far (about 10 attempts). Once
detected, the COM ports seem to work just fine.
I downloaded serialblaster and I see where this is being printed in
the Initialize_UARTS section of the ts7250-bootrom.S file.
Is this likely to be a power issue or something else? Should I insert
some sort of delay into the bootrom code to stabilize the power? Does
the serialblaster bootrom code handle uart initialization any differently?
The UARTS themselves are TL16C550CFN devices from Texas Instruments,
chosen for maximum compatibility with the 2.4 kernel.
Thanks,
Tom Johnson
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