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Documentation: gpio: Input mode is not true Hi-Z

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The true Hi-Z (a.k.a. high impedance) mode is when pin is completely
disconnected from the chip. This includes input buffer as well.
Nevertheless, some hardware may not support that mode and they are
considering input only as Hi-Z, but more precisely it is an equivalent
to that, in electronics it's basically "an antenna mode".

Sligthly correct documentation to take the above into consideration.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
This commit is contained in:
Andy Shevchenko 2022-11-30 17:55:17 +02:00 committed by Bartosz Golaszewski
parent db4064cc10
commit 5b3b3e35ac
1 changed files with 4 additions and 4 deletions
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8
Documentation/driver-api/gpio/driver.rst
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@ -218,10 +218,10 @@ not support open drain/open source in hardware, the GPIO library will instead
use a trick: when a line is set as output, if the line is flagged as open
drain, and the IN output value is low, it will be driven low as usual. But
if the IN output value is set to high, it will instead *NOT* be driven high,
instead it will be switched to input, as input mode is high impedance, thus
achieving an "open drain emulation" of sorts: electrically the behaviour will
be identical, with the exception of possible hardware glitches when switching
the mode of the line.
instead it will be switched to input, as input mode is an equivalent to
high impedance, thus achieving an "open drain emulation" of sorts: electrically
the behaviour will be identical, with the exception of possible hardware glitches
when switching the mode of the line.
For open source configuration the same principle is used, just that instead
of actively driving the line low, it is set to input.