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Diffstat (limited to 'Documentation/userspace-api/gpio/gpio-handle-get-line-values-ioctl.rst')
| -rw-r--r-- | Documentation/userspace-api/gpio/gpio-handle-get-line-values-ioctl.rst | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/userspace-api/gpio/gpio-handle-get-line-values-ioctl.rst b/Documentation/userspace-api/gpio/gpio-handle-get-line-values-ioctl.rst index 25263b8f0588..2e3a52c113d5 100644 --- a/Documentation/userspace-api/gpio/gpio-handle-get-line-values-ioctl.rst +++ b/Documentation/userspace-api/gpio/gpio-handle-get-line-values-ioctl.rst @@ -36,6 +36,13 @@ Description Get the values of all requested lines. +The values returned are logical, indicating if the line is active or inactive. +The ``GPIOHANDLE_REQUEST_ACTIVE_LOW`` flag controls the mapping between physical +values (high/low) and logical values (active/inactive). +If ``GPIOHANDLE_REQUEST_ACTIVE_LOW`` is not set then high is active and +low is inactive. If ``GPIOHANDLE_REQUEST_ACTIVE_LOW`` is set then low is active +and high is inactive. + The values of both input and output lines may be read. For output lines, the value returned is driver and configuration dependent and |