8250.c::autoconfig() fails loopback test on MPC824[15]

[Guennadi Liakhovetski]

Hi,

I tried using of_serial.c on a (PPC) MPC8241 based system, which has a 
"16650A" compatible double UART built into the SoC. Using of_serial.c 
causes the ports to be autoconfigured, and this fails. The loopback test 
fails, because the MSR register on 824[15] doesn't implement the 
UART_MSR_DCD bit. Question: what's better, teach 8250.c to handle UARTs 
without this bit, or set the UPF_SKIP_TEST bit in of_serial.c for these 
SOCs to skip the loopback test altogether? The latter is certainly easier 
and affects much fewer systems, so, I'd go for that.

Thanks
Guennadi
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Guennadi Liakhovetski