gpio calls don't need i/o barriers

Clarify that drivers using the GPIO operations don't need to issue io
barrier instructions themselves.  Previously this wasn't clear, and at
least one platform assumed otherwise (and would thus break various
otherwise-portable drivers which don't issue barriers).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt
index 36af58eba136bac198ea3b1f33f34236be9ce5df..218a8650f48dea441ce4b5777416f028fff518f8 100644 (file)
--- a/Documentation/gpio.txt
+++ b/Documentation/gpio.txt
@@ -75,6 +75,9 @@ using the include file:
 If you stick to this convention then it'll be easier for other developers to
 see what your code is doing, and help maintain it.
 
+Note that these operations include I/O barriers on platforms which need to
+use them; drivers don't need to add them explicitly.
+
 
 Identifying GPIOs
 -----------------