TL16C752B DUART: MCR_OUT2 disables interrupts

[Shaun Jackman]

The datasheet I have for the TL16C752B labels the MCR_OUT1 bit as
`FIFO Rdy enable' and the MCR_OUT2 bit as `IRQ enable'. The latter bit
concerns me. The 8250.c driver sets MCR_OUT2 by default; however, if
the user space clears MCR_OUT2 (through an ioctl TIOCMSET operation or
similar), it seems to me that interrupts for that UART will stop
working. Can someone confirm my suspicion?

I'd expect that clearing/setting the OUT1 and OUT2 pins from user
space should be an innocuous operation. Disabling interrupts is a
fairly nasty side effect.

Please cc me in your reply. Cheers,
Shaun
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