Re: Using Pull-up resistors on gpio-pca953x expander

[Linus Walleij]

On Wed, Jan 15, 2020 at 9:26 PM Adam Ford <aford173@xxxxxxxxx> wrote:

> The pca953x can support pull-up resistors, and I have a pcal6416 that
> I'd like to enable them.

OK this is supported in the driver since
commit 15add06841a3b0b4734a72847a73c71fd09ebe52
"gpio: pca953x: add ->set_config implementation"

> Ideally, I was hoping there would be a way to add enable to the device
> tree, because the expander is connected to some buttons which are
> grounded when pressed.  Without pull-up resistors enabled, the buttons
> always appear to be pressed.
>
> Is there some way to enable them?  I see the functionality is
> available and called through gc->set_config = pca953x_gpio_set_config;
(...)
> Would you entertain my adding some device tree hooks to enable them?

Have you tried something like this in your DTS:

#include <dt-bindings/gpio/gpio.h>
(...)
gpios = <&gpio 4 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;

Yours,
Linus Walleij