Subject: Re: [PATCH v1 1/1] arm64: dts: imx91-var-som-symphony: fix RGB_SEL handling

From: Stefano Radaelli <[email-masked]>
Date: Wed, 3 Jun 2026 11:12:16 +0200

Hi Frank,

On Mon, Jun 01, 2026 at 04:42:32PM -0400, Frank Li wrote:
> On Fri, May 29, 2026 at 03:48:50PM +0200, Stefano Radaelli wrote:
> > From: Stefano Radaelli <[email-masked]>
> >
> > RGB_SEL is a board-level signal driven by the PCAL6408 GPIO expander on
> > the Symphony carrier board.
> >
> > The signal needs to be driven high on the i.MX91 variant to keep the
> > board in the expected display configuration. Move the handling of this
> > line from a fixed regulator tied to the PCAL6408 supply to a GPIO hog on
> > the correct GPIO expander.
> 
> Look like this can't resolve your problem.  gpio driver may probe later
> than display, so gpio-hog may not set correct when display setup.
> 
> Frank
> >

thanks for looking at this.

The main issue I am trying to fix here is that the current upstream DT
describes RGB_SEL on the wrong GPIO expander.

The existing DT drives RGB_SEL from pca9534 GPIO 7 and also uses it as a
fake supply for the pca6408. That is not correct for this board. RGB_SEL
is actually connected to pca6408 GPIO 7, so the current description does
not drive the intended line at all.

With this change, RGB_SEL is driven by the correct GPIO controller and
this fixes the hardware configuration issue I am seeing on the i.MX91
Symphpony board, making it working now as expected.

Best Regards,
Stefano