linux-kernel - RE: [PATCH] arm64: dts: imx93-evk/qsb: add m2-pcm-level-shifter-hog to enable BT HFP

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Message-ID:
 <VI0PR04MB121142D337B54A448ED64EC419296A@VI0PR04MB12114.eurprd04.prod.outlook.com>
Date: Wed, 21 Jan 2026 06:54:11 +0000
From: Sherry Sun <sherry.sun@....com>
To: Frank Li <frank.li@....com>
CC: "robh@...nel.org" <robh@...nel.org>, "krzk+dt@...nel.org"
	<krzk+dt@...nel.org>, "conor+dt@...nel.org" <conor+dt@...nel.org>,
	"shawnguo@...nel.org" <shawnguo@...nel.org>, "s.hauer@...gutronix.de"
	<s.hauer@...gutronix.de>, "festevam@...il.com" <festevam@...il.com>,
	"kernel@...gutronix.de" <kernel@...gutronix.de>, "devicetree@...r.kernel.org"
	<devicetree@...r.kernel.org>, "imx@...ts.linux.dev" <imx@...ts.linux.dev>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] arm64: dts: imx93-evk/qsb: add m2-pcm-level-shifter-hog
 to enable BT HFP

> Subject: Re: [PATCH] arm64: dts: imx93-evk/qsb: add m2-pcm-level-shifter-
> hog to enable BT HFP
> 
> On Tue, Jan 20, 2026 at 04:32:33PM +0800, Sherry Sun wrote:
> > For i.MX93 11x11 EVK and 9x9 QSB boards, add the gpio-hog to enable
> > the
> > M.2 PCM pins level shifter connected between soc sai1 interface and
> > M.2 PCM pins so that HFP feature can be supported.
> 
> Does sai1 have any refer to pcal6524? sai may probe before pcal6524, so m2-
> pcm-level-shifter-hog may not set when sai probe.

Hi Frank,

Since the HFP functionality is only used at a later stage — after the BT firmware has been
downloaded and the Bluetooth connection with the remote device has been established
— both the pcal6524 expander and sai1 interface are already fully initialized and available
by that time. Therefore, using a gpio-hog here will not introduce any probe‑ordering or
dependency issues for the HFP use case.

Best Regards
Sherry
> 
> Frank
> >
> > Signed-off-by: Sherry Sun <sherry.sun@....com>
> > ---
> >  arch/arm64/boot/dts/freescale/imx93-11x11-evk.dts | 6 ++++++
> >  arch/arm64/boot/dts/freescale/imx93-9x9-qsb.dts   | 6 ++++++
> >  2 files changed, 12 insertions(+)
> >
> > diff --git a/arch/arm64/boot/dts/freescale/imx93-11x11-evk.dts
> > b/arch/arm64/boot/dts/freescale/imx93-11x11-evk.dts
> > index 8dd5340e8141..acb160d3186c 100644
> > --- a/arch/arm64/boot/dts/freescale/imx93-11x11-evk.dts
> > +++ b/arch/arm64/boot/dts/freescale/imx93-11x11-evk.dts
> > @@ -356,6 +356,12 @@ pcal6524: gpio@22 {
> >  		#interrupt-cells = <2>;
> >  		interrupt-parent = <&gpio3>;
> >  		interrupts = <27 IRQ_TYPE_LEVEL_LOW>;
> > +
> > +		m2-pcm-level-shifter-hog {
> > +			gpio-hog;
> > +			gpios = <19 GPIO_ACTIVE_HIGH>;
> > +			output-high;
> > +		};
> >  	};
> >
> >  	pmic@25 {
> > diff --git a/arch/arm64/boot/dts/freescale/imx93-9x9-qsb.dts
> > b/arch/arm64/boot/dts/freescale/imx93-9x9-qsb.dts
> > index 0852067eab2c..11e08673083b 100644
> > --- a/arch/arm64/boot/dts/freescale/imx93-9x9-qsb.dts
> > +++ b/arch/arm64/boot/dts/freescale/imx93-9x9-qsb.dts
> > @@ -349,6 +349,12 @@ mic-can-sel-hog {
> >  			gpios = <17 GPIO_ACTIVE_HIGH>;
> >  			output-low;
> >  		};
> > +
> > +		m2-pcm-level-shifter-hog {
> > +			gpio-hog;
> > +			gpios = <19 GPIO_ACTIVE_HIGH>;
> > +			output-high;
> > +		};
> >  	};
> >
> >  	pmic@25 {
> > --
> > 2.37.1
> >