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Diffstat (limited to 'Documentation/gpio.txt')
| -rw-r--r-- | Documentation/gpio.txt | 4 |
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 | |||
| 240 | needed to manage a signal that's in active use. That is, requesting a | 240 | needed to manage a signal that's in active use. That is, requesting a |
| 241 | GPIO can serve as a kind of lock. | 241 | GPIO can serve as a kind of lock. |
| 242 | 242 | ||
| 243 | Some platforms may also use knowledge about what GPIOs are active for | ||
| 244 | power management, such as by powering down unused chip sectors and, more | ||
| 245 | easily, gating off unused clocks. | ||
| 246 | |||
| 243 | These two calls are optional because not not all current Linux platforms | 247 | These two calls are optional because not not all current Linux platforms |
| 244 | offer such functionality in their GPIO support; a valid implementation | 248 | offer such functionality in their GPIO support; a valid implementation |
| 245 | could return success for all gpio_request() calls. Unlike the other calls, | 249 | could return success for all gpio_request() calls. Unlike the other calls, |