diff options
| author | Justin Waters <justin.waters@timesys.com> | 2008-02-26 13:07:02 -0500 |
|---|---|---|
| committer | Justin Waters <justin.waters@timesys.com> | 2008-02-26 13:07:02 -0500 |
| commit | b80a32b9cc634adfa8eaef33ec981e7febf2ade2 (patch) | |
| tree | f256bce13ba11f514a388160df84e1410bedbe2b /Documentation/gpio.txt | |
| parent | 594133ef22fae0d737bd1b57352cf3f48a192c63 (diff) | |
Update the i.MX31 Kernel to 2.6.232.6.23-mx31ads-2008022618072.6.23-mx31-200802261807
This is the result of a brute-force attempt to update the kernel to 2.6.23.
Now that we have a git tree, our effort will be a little nicer in the future.
Signed-off-by: Justin Waters <justin.waters@timesys.com>
Diffstat (limited to 'Documentation/gpio.txt')
| -rw-r--r-- | Documentation/gpio.txt | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt index 36af58eba136..6bc2ba215df9 100644 --- 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 ----------------- @@ -145,7 +148,7 @@ pin ... that won't always match the specified output value, because of issues including wire-OR and output latencies. The get/set calls have no error returns because "invalid GPIO" should have -been reported earlier in gpio_set_direction(). However, note that not all +been reported earlier from gpio_direction_*(). However, note that not all platforms can read the value of output pins; those that can't should always return zero. Also, using these calls for GPIOs that can't safely be accessed without sleeping (see below) is an error. @@ -236,7 +239,7 @@ map between them using calls like: Those return either the corresponding number in the other namespace, or else a negative errno code if the mapping can't be done. (For example, some GPIOs can't used as IRQs.) It is an unchecked error to use a GPIO -number that hasn't been marked as an input using gpio_set_direction(), or +number that wasn't set up as an input using gpio_direction_input(), or to use an IRQ number that didn't originally come from gpio_to_irq(). These two mapping calls are expected to cost on the order of a single |