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-rw-r--r--Documentation/gpio.txt8
1 files changed, 6 insertions, 2 deletions
diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt
index e8be0abb346c..36af58eba136 100644
--- a/Documentation/gpio.txt
+++ b/Documentation/gpio.txt
@@ -111,7 +111,9 @@ setting up a platform_device using the GPIO, is mark its direction:
111 111
112The return value is zero for success, else a negative errno. It should 112The return value is zero for success, else a negative errno. It should
113be checked, since the get/set calls don't have error returns and since 113be checked, since the get/set calls don't have error returns and since
114misconfiguration is possible. (These calls could sleep.) 114misconfiguration is possible. You should normally issue these calls from
115a task context. However, for spinlock-safe GPIOs it's OK to use them
116before tasking is enabled, as part of early board setup.
115 117
116For output GPIOs, the value provided becomes the initial output value. 118For output GPIOs, the value provided becomes the initial output value.
117This helps avoid signal glitching during system startup. 119This helps avoid signal glitching during system startup.
@@ -197,7 +199,9 @@ However, many platforms don't currently support this mechanism.
197 199
198Passing invalid GPIO numbers to gpio_request() will fail, as will requesting 200Passing invalid GPIO numbers to gpio_request() will fail, as will requesting
199GPIOs that have already been claimed with that call. The return value of 201GPIOs that have already been claimed with that call. The return value of
200gpio_request() must be checked. (These calls could sleep.) 202gpio_request() must be checked. You should normally issue these calls from
203a task context. However, for spinlock-safe GPIOs it's OK to request GPIOs
204before tasking is enabled, as part of early board setup.
201 205
202These calls serve two basic purposes. One is marking the signals which 206These calls serve two basic purposes. One is marking the signals which
203are actually in use as GPIOs, for better diagnostics; systems may have 207are actually in use as GPIOs, for better diagnostics; systems may have