Merge branch 'kvm-updates-2.6.27' of git://git.kernel.org/pub/scm/linux/kernel/git...

[pandora-kernel.git] / Documentation / tty.txt

diff --git a/Documentation/tty.txt b/Documentation/tty.txt
index 5f799e6..8e65c44 100644 (file)
--- a/Documentation/tty.txt
+++ b/Documentation/tty.txt
@@ -108,7 +108,9 @@ hardware driver through the function pointers within the tty->driver
 structure:
 
 write()                        Write a block of characters to the tty device.
-                       Returns the number of characters accepted.
+                       Returns the number of characters accepted. The
+                       character buffer passed to this method is already
+                       in kernel space.
 
 put_char()             Queues a character for writing to the tty device.
                        If there is no room in the queue, the character is
@@ -130,6 +132,14 @@ set_termios()              Notify the tty driver that the device's termios
                        tty->termios. Previous settings should be passed in
                        the "old" argument.
 
+                       The API is defined such that the driver should return
+                       the actual modes selected. This means that the
+                       driver function is responsible for modifying any
+                       bits in the request it cannot fulfill to indicate
+                       the actual modes being used. A device with no
+                       hardware capability for change (eg a USB dongle or
+                       virtual port) can provide NULL for this method.
+
 throttle()             Notify the tty driver that input buffers for the
                        line discipline are close to full, and it should
                        somehow signal that no more characters should be