On Tuesday 28 March 2017 02:36 PM, Linus Walleij wrote:
On Mon, Mar 27, 2017 at 5:21 PM, Laxman Dewangan <ldewangan@xxxxxxxxxx> wrote:
I have the schematics, where I need to set it as
Pin state HIGH (by setting gpio-input mode) to enable the circuit.
Pin state LOW (by setting gpio-output mode with value to 0) to disable the
circuit.
(...)
With this, I think the GPIO is active HIGH and open drain type.
If I set the active LOW from DT then I can not set pin to logical 1 using
the API gpiod_set_value() with “1”.
As this invert before calling _gpiod_set_raw_value() and so the value = 0
and it set the pin in the gpio mode output-Low.
Shouldn'’t open drain pin are active HIGH?
Sorry I do not understand, have you solved it?
I wanted to say that open drain flag should be with ACTIVE_HIGH |
SINGLE_ENDED which is in inverted as of now.
Else can you try to break down the problem, do you mean there is a bug
in inverted handling for open drain lines in gpiolib?
Yes, I am suspecting the bug here with combination of ACTIVE state and
SINGLE_ENDED flag. The logic to get OPEN DRAIN flag should be in
inverted form.
Else we need to decouple the ACTIVE state with SINGLE_ENDED flag to get
Open drain or open source.
If I want to say logical "1" for the open drain, it is setting pin in
drive-0 mode. Actually, it should be in input mode so that pin state
become HIGH.
In function of_find_gpio(), it is as follows:
if (of_flags & OF_GPIO_SINGLE_ENDED) {
if (of_flags & OF_GPIO_ACTIVE_LOW)
*flags |= GPIO_OPEN_DRAIN;
else
*flags |= GPIO_OPEN_SOURCE;
}
I think it should be
if (of_flags & OF_GPIO_SINGLE_ENDED) {
if (of_flags & OF_GPIO_ACTIVE_LOW)
*flags |= GPIO_OPEN_SOURCE;
else
*flags |= GPIO_OPEN_DRAIN;
}
Similar change is needed in the dtbinding gpio header also to invert the
ACTIVE state with open drain/source.
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