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authorYegor Yefremov <yegor_sub1@visionsystems.de>2010-11-22 11:06:32 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2010-11-30 17:26:04 -0800
commitde6f86ce51341559dc3c9c9f5c562da12fcfcb31 (patch)
tree01a51dca4ea1a201d6aa01988945d419ec84c397 /Documentation/serial
parenta4fb0b228e284107b9bdf44769bbdc80efd660e1 (diff)
downloadlinux-de6f86ce51341559dc3c9c9f5c562da12fcfcb31.tar.gz
RS485 documentation: add 16C950 UART description
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>
Diffstat (limited to 'Documentation/serial')
-rw-r--r--Documentation/serial/serial-rs485.txt9
1 files changed, 5 insertions, 4 deletions
diff --git a/Documentation/serial/serial-rs485.txt b/Documentation/serial/serial-rs485.txt
index a3b1af7b6db..a4932387bbf 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