Re: [PATCH v1 1/1] arm64: dts: imx91-var-dart-sonata: add RGB select supply for PCA6408

[Stefano Radaelli]

Hi Frank,

On Fri, Mar 27, 2026 at 12:51:25PM -0400, Frank Li wrote:
> On Fri, Mar 27, 2026 at 05:32:43PM +0100, Stefano Radaelli wrote:
> > From: Stefano Radaelli <stefano.r@xxxxxxxxxxxxx>
> >
> > RGB_SEL controls the routing of some carrier board lines on the Sonata
> > board. The two PCA6408 GPIO expanders depend on that path being enabled,
> > so describe the selector as a fixed regulator and use it as their
> > vcc-supply.
> 
> Does below resolve your problem?
>  https://lore.kernel.org/imx/20260325-pinctrl-mux-v4-0-043c2c82e623@xxxxxxx/
> 
> So needn't hack select as regualtor
> 

Thanks for pointing me your patch, interesting improvement!

Actually, in this case RGB_SEL is not meant to model a selectable mux
on the Sonata carrier.
On this board it must stay asserted permanently, otherwise the
downstream path to the two PCA6408 expanders is not accessible.

Modeling it as a mux might be confusing for users of the DART-MX91, as
as it would suggest that the routing is configurable, while on this
board it is actually fixed.

Best Regards,
Stefano