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Subject[PATCH 20/36] RS485 documentation: add 16C950 UART description
Date
From: Yegor Yefremov <yegor_sub1@visionsystems.de>

Add a notion about 16C950 UART, that is using DTR signal for RS485 mode.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
Documentation/serial/serial-rs485.txt | 9 +++++----
1 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/Documentation/serial/serial-rs485.txt b/Documentation/serial/serial-rs485.txt
index a3b1af7..a493238 100644
--- a/Documentation/serial/serial-rs485.txt
+++ b/Documentation/serial/serial-rs485.txt
@@ -11,10 +11,11 @@

2. HARDWARE-RELATED CONSIDERATIONS

- Some CPUs (e.g., Atmel AT91) contain a built-in half-duplex mode capable of
- automatically controlling line direction by toggling RTS. That can used to
- control external half-duplex hardware like an RS485 transceiver or any
- RS232-connected half-duplex device like some modems.
+ Some CPUs/UARTs (e.g., Atmel AT91 or 16C950 UART) contain a built-in
+ half-duplex mode capable of automatically controlling line direction by
+ toggling RTS or DTR signals. That can be used to control external
+ half-duplex hardware like an RS485 transceiver or any RS232-connected
+ half-duplex devices like some modems.

For these microcontrollers, the Linux driver should be made capable of
working in both modes, and proper ioctls (see later) should be made
--
1.7.3.2


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