From 48a22edb4ae2ef41969095abc5a514910361ee58 Mon Sep 17 00:00:00 2001 From: Joel Sherrill Date: Tue, 9 Jul 2013 11:15:57 -0500 Subject: libchip ns16550.c: Improve comment --- c/src/libchip/serial/ns16550.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'c/src/libchip') diff --git a/c/src/libchip/serial/ns16550.c b/c/src/libchip/serial/ns16550.c index de2245651f..829284a86c 100644 --- a/c/src/libchip/serial/ns16550.c +++ b/c/src/libchip/serial/ns16550.c @@ -501,10 +501,13 @@ int ns16550_set_attributes( /* * Set the baud rate + * + * NOTE: When the Divisor Latch Access Bit (DLAB) is set to 1, + * the transmit buffer and interrupt enable registers + * turn into the LSB and MSB divisor latch registers. */ (*setReg)(pNS16550, NS16550_LINE_CONTROL, SP_LINE_DLAB); - /* XXX are these registers right? */ (*setReg)(pNS16550, NS16550_TRANSMIT_BUFFER, ulBaudDivisor&0xff); (*setReg)(pNS16550, NS16550_INTERRUPT_ENABLE, (ulBaudDivisor>>8)&0xff); -- cgit v1.2.3