linux-kernel - Re: [PATCH] arm64: dts: imx8mm-verdin: Link reg_nvcc

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Message-ID: <95107ed358b735cbe9e5a1af20a2d6db74c5ed64.camel@impulsing.ch>
Date: Tue, 22 Apr 2025 07:57:32 +0000
From: Philippe Schenker <philippe.schenker@...ulsing.ch>
To: Francesco Dolcini <francesco@...cini.it>, Wojciech Dubowik
	<Wojciech.Dubowik@...com>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Rob Herring
	<robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
	<conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>, Sascha Hauer
	<s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, "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>, "stable@...r.kernel.org"
	<stable@...r.kernel.org>
Subject: Re: [PATCH] arm64: dts: imx8mm-verdin: Link reg_nvcc_sd to usdhc2

Hi Francesco,

Just for your awareness, I stumbled on this patch this morning and I
actually did the exact same thing on verdin-imx8mp a while ago:
c8d29601fea3080a42731e8535b929a93afa107e

Not sure this causes any side-effects maybe you guys want to
investigate further about this. I needed it due to the strange
requirements I had (described in commit message).
From my point of view it is correct to link the vqmmc-supply so the
voltage can be set also to something different than the default fusing
values.

Philippe

On Thu, 2025-04-17 at 15:03 +0200, Francesco Dolcini wrote:
> Hello Wojciech,
> thanks very much for your patch.
> 
> On Thu, Apr 17, 2025 at 01:20:11PM +0200, Wojciech Dubowik wrote:
> > Link LDO5 labeled reg_nvcc_sd from PMIC to align with
> > hardware configuration specified in the datasheet.
> > 
> > Without this definition LDO5 will be powered down, disabling
> > SD card after bootup. This has been introduced in commit
> > f5aab0438ef1 (regulator: pca9450: Fix enable register for LDO5).
> > 
> > Fixes: f5aab0438ef1 (regulator: pca9450: Fix enable register for
> > LDO5)
> > Cc: stable@...r.kernel.org
> > 
> > Signed-off-by: Wojciech Dubowik <Wojciech.Dubowik@...com>
> > ---
> >  arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi
> > b/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi
> > index 7251ad3a0017..6307c5caf3bc 100644
> > --- a/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi
> > +++ b/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi
> > @@ -785,6 +785,7 @@ &usdhc2 {
> >   pinctrl-2 = <&pinctrl_usdhc2_200mhz>, <&pinctrl_usdhc2_cd>;
> >   pinctrl-3 = <&pinctrl_usdhc2_sleep>, <&pinctrl_usdhc2_cd_sleep>;
> >   vmmc-supply = <&reg_usdhc2_vmmc>;
> > + vqmmc-supply = <&reg_nvcc_sd>;
> 
> I am worried just doing this will have some side effects.
> 
> Before this patch, the switch between 1v8 and 3v3 was done because we
> have a GPIO, connected to the PMIC, controlled by the USDHC2 instance
> (MX8MM_IOMUXC_GPIO1_IO04_USDHC2_VSELECT, see pinctrl_usdhc2).
> 
> With your change both the PMIC will be programmed with a different
> voltage over i2c and the GPIO will also toggle. It does not sound
> like
> what we want to do.
> 
> Maybe we should have a "regulator-gpio" with vin-supply =
> <&reg_nvcc_sd>, as we recently did here
> https://lore.kernel.org/all/20250414123827.428339-1-
> ivitro@...il.com/T/#m2964f1126a6732a66a6e704812f2b786e8237354
> ?
> 
> Francesco
> 

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