path: root/Documentation/serial
diff options
authorRussell King <>2005-08-31 10:12:14 +0100
committerRussell King <>2005-08-31 10:12:14 +0100
commitb129a8ccd53f74c43e4c83c8e0031a4990040830 (patch)
tree4c40afd836be87166d6d014380262f1baa19694f /Documentation/serial
parent6b39374a27eb4be7e9d82145ae270ba02ea90dc8 (diff)
parent194d0710e1a7fe92dcf860ddd31fded8c3103b7a (diff)
[SERIAL] Clean up and fix tty transmission start/stoping
The start_tx and stop_tx methods were passed a flag to indicate whether the start/stop was from the tty start/stop callbacks, and some drivers used this flag to decide whether to ask the UART to immediately stop transmission (where the UART supports such a feature.) There are other cases when we wish this to occur - when CTS is lowered, or if we change from soft to hard flow control and CTS is inactive. In these cases, this flag was false, and we would allow the transmitter to drain before stopping. There is really only one case where we want to let the transmitter drain before disabling, and that's when we run out of characters to send. Hence, re-jig the start_tx and stop_tx methods to eliminate this flag, and introduce new functions for the special "disable and allow transmitter to drain" case. Signed-off-by: Russell King <>
Diffstat (limited to 'Documentation/serial')
1 files changed, 4 insertions, 11 deletions
diff --git a/Documentation/serial/driver b/Documentation/serial/driver
index ac7eabbf662a..87856d3cfb67 100644
--- a/Documentation/serial/driver
+++ b/Documentation/serial/driver
@@ -111,24 +111,17 @@ hardware.
Interrupts: locally disabled.
This call must not sleep
- stop_tx(port,tty_stop)
+ stop_tx(port)
Stop transmitting characters. This might be due to the CTS
line becoming inactive or the tty layer indicating we want
- to stop transmission.
- tty_stop: 1 if this call is due to the TTY layer issuing a
- TTY stop to the driver (equiv to rs_stop).
+ to stop transmission due to an XOFF character.
Locking: port->lock taken.
Interrupts: locally disabled.
This call must not sleep
- start_tx(port,tty_start)
- start transmitting characters. (incidentally, nonempty will
- always be nonzero, and shouldn't be used - it will be dropped).
- tty_start: 1 if this call was due to the TTY layer issuing
- a TTY start to the driver (equiv to rs_start)
+ start_tx(port)
+ start transmitting characters.
Locking: port->lock taken.
Interrupts: locally disabled.