summaryrefslogtreecommitdiff
path: root/Documentation/gpio.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/gpio.txt')
-rw-r--r--Documentation/gpio.txt4
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt
index 8a7c45956d24..b1b988701247 100644
--- a/Documentation/gpio.txt
+++ b/Documentation/gpio.txt
@@ -240,6 +240,10 @@ signal, or (b) something wrongly believes it's safe to remove drivers
needed to manage a signal that's in active use. That is, requesting a
GPIO can serve as a kind of lock.
+Some platforms may also use knowledge about what GPIOs are active for
+power management, such as by powering down unused chip sectors and, more
+easily, gating off unused clocks.
+
These two calls are optional because not not all current Linux platforms
offer such functionality in their GPIO support; a valid implementation
could return success for all gpio_request() calls. Unlike the other calls,