tty: docs: serial/tty, add to ldisc methods

A small addition to the ldisc method descriptions.

Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 7 insertions, 2 deletions

diff --git a/Documentation/serial/tty.txt b/Documentation/serial/tty.txt
index 8e65c4498c52..5e5349a4fcd2 100644
--- a/Documentation/serial/tty.txt
+++ b/Documentation/serial/tty.txt
@@ -42,7 +42,8 @@ TTY side interfaces:
 open()          -       Called when the line discipline is attached to
                         the terminal. No other call into the line
                         discipline for this tty will occur until it
-                        completes successfully. Can sleep.
+                        completes successfully. Returning an error will
+                        prevent the ldisc from being attached. Can sleep.
 
 close()         -       This is called on a terminal when the line
                         discipline is being unplugged. At the point of
@@ -52,7 +53,7 @@ close()		-	This is called on a terminal when the line
 hangup()        -       Called when the tty line is hung up.
                         The line discipline should cease I/O to the tty.
                         No further calls into the ldisc code will occur.
-                        Can sleep.
+                        The return value is ignored. Can sleep.
 
 write()         -       A process is writing data through the line
                         discipline.  Multiple write calls are serialized
@@ -83,6 +84,10 @@ ioctl()		-	Called when an ioctl is handed to the tty layer
                         that might be for the ldisc. Multiple ioctl calls
                         may occur in parallel. May sleep. 
 
+compat_ioctl()  -       Called when a 32 bit ioctl is handed to the tty layer
+                        that might be for the ldisc. Multiple ioctl calls
+                        may occur in parallel. May sleep.
+
 Driver Side Interfaces:
 
 receive_buf()   -       Hand buffers of bytes from the driver to the ldisc