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extend documentation for gpiod_set_array() functions 

Extend the documentation for the gpiod_set_array() functions and elaborate
a bit on possible use cases.

Signed-off-by: Rojhalat Ibrahim <imr@rtschenk.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Rojhalat Ibrahim 2015-03-05 14:36:36 +01:00 committed by Linus Walleij
parent 39521090e9
commit de3b696542
1 changed files with 20 additions and 0 deletions
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20
Documentation/gpio/consumer.txt
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@ -259,6 +259,26 @@ GPIOs belonging to the same bank or chip simultaneously if supported by the
corresponding chip driver. In that case a significantly improved performance
can be expected. If simultaneous setting is not possible the GPIOs will be set
sequentially.
The gpiod_set_array() functions take three arguments:
* array_size - the number of array elements
* desc_array - an array of GPIO descriptors
* value_array - an array of values to assign to the GPIOs
The descriptor array can be obtained using the gpiod_get_array() function
or one of its variants. If the group of descriptors returned by that function
matches the desired group of GPIOs, those GPIOs can be set by simply using
the struct gpio_descs returned by gpiod_get_array():
struct gpio_descs *my_gpio_descs = gpiod_get_array(...);
gpiod_set_array(my_gpio_descs->ndescs, my_gpio_descs->desc,
my_gpio_values);
It is also possible to set a completely arbitrary array of descriptors. The
descriptors may be obtained using any combination of gpiod_get() and
gpiod_get_array(). Afterwards the array of descriptors has to be setup
manually before it can be used with gpiod_set_array().
Note that for optimal performance GPIOs belonging to the same chip should be
contiguous within the array of descriptors.