Re: Serial: UART_BUG_TXEN race conditions

[H. Peter Anvin]

linux-os (Dick Johnson) wrote:
> With 8250 UARTs and clones, an interrupt occurs when the
> transmitter holding register __becomes__ empty. That means
> it must have had something in it.

Dear Wrongbot,

That's what some people think, and that's how they end up shipping buggy 
hardware.

With 16x50 UARTs, an interrupt occurs *when an interrupt condition is 
asserted*, which can happen either though a state change or on a change 
in IER.

	-hpa
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