Re: [PATCH] i2c: muxes: pca954x: Fix broken reset-gpio usage

Krzysztof Kozlowski
2025-11-03T15:36:32Z

On 03/11/2025 16:19, Krzysztof Kozlowski wrote:
> Revert commit 690de2902dca ("i2c: muxes: pca954x: Use reset controller
> only") and its dependent commit 94c296776403 ("i2c: muxes: pca954x:
> Reset if (de)select fails") because the first breaks all users of the
> driver, by requiring a completely optional reset-gpio driver. These
> commits cause that mux driver simply stops working when optional
> reset-gpio is not included, but that reset-gpio is not pulled anyhow.
>
> Driver cannot remove legacy reset-gpios handling.
>
> Fixes: 690de2902dca ("i2c: muxes: pca954x: Use reset controller only")
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> ---

Maybe I should also add to emphasize:

That offending commit 690de2902dca breaks the ABI which was:
1. documented at
Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.yaml (line 57)
2. implemented in Linux kernel around v3.14.

This ABI breakage was not justified at all, not explained not even
mentioned in the commit msg, which is a requirement (see writing
bindings document).

Best regards,
Krzysztof