Re: [PATCH 2/2] gpio: pcf857x: add support for reset-gpios on (most) PCA967x

[Heiko Stübner]

Am Donnerstag, 20. Februar 2025, 10:56:52 MEZ schrieb Quentin Schulz:
> From: Quentin Schulz <quentin.schulz@xxxxxxxxx>
> 
> The PCA9670, PCA9671, PCA9672 and PCA9673 all have a RESETN input pin
> that is used to reset the I2C GPIO expander.
> 
> One needs to hold this pin low for at least 4us and the reset should be
> finished after about 100us according to the datasheet[1]. Once the reset
> is done, the "registers and I2C-bus state machine will be held in their
> default state until the RESET input is once again HIGH.".
> 
> Because the logic is reset, the latch values eventually provided in the
> Device Tree via lines-initial-states property are inapplicable so they
> are simply ignored if a reset GPIO is provided.
> 
> [1] https://www.nxp.com/docs/en/data-sheet/PCA9670.pdf 8.5 and fig 22.
> Signed-off-by: Quentin Schulz <quentin.schulz@xxxxxxxxx>

With the gpio-consumer fixed, reset-gpio handling works nicely
on my rk3588-tiger-haikou with the DSI display overlay, so

Tested-by: Heiko Stuebner <heiko@xxxxxxxxx>