linux-kernel - Re: [PATCH 05/13] arm64: dts: freescale: imx93-phycore-som: Add eMMC no-1-8-v by default

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Message-ID: <Z/kn9fGfH1PeyMxW@lizhi-Precision-Tower-5810>
Date: Fri, 11 Apr 2025 10:32:21 -0400
From: Frank Li <Frank.li@....com>
To: Primoz Fiser <primoz.fiser@...ik.com>
Cc: 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,
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, upstream@...ts.phytec.de
Subject: Re: [PATCH 05/13] arm64: dts: freescale: imx93-phycore-som: Add eMMC
 no-1-8-v by default

On Fri, Apr 11, 2025 at 08:51:18AM +0200, Primoz Fiser wrote:
> Hi Frank,
>
> On 10. 04. 25 17:01, Frank Li wrote:
> > On Thu, Apr 10, 2025 at 11:02:43AM +0200, Primoz Fiser wrote:
> >> Add property 'no-1-8-v' by default to usdhc1 (eMMC) node. Bootloader
> >> will take care of deleting the property in case SOM supports HS400 mode
> >> (1.8V IO voltage feature flag has to be set in the EEPROM).
> >
> > what means of EEPROM here?
> >
> > Generally eMMC worked fixed voltage, why need 'no-1-8-v' here, even no
> > HS400 support.
>
> The phyCORE-i.MX93 SoM comes in two variants, one with 3.3V VDD_IO and
> the other one with 1.8V VDD_IO voltage set.
>
> The 3.3V variant can only support DDR52 mode, while 1.8V variant will
> support HS400ES eMMC mode.
>
> The information about VDD_IO option is encoded in the SoM's EEPROM. We
> read EEPROM in the bootloader and clear "no-1-8-v" flag in case of 1.8V
> SOM variant is detected.
>
> In case of EEPROM error (erased or read error) the fall-back option has
> to support both SoM variants, hence the "no-1-8-v" flag has to be set by
> default.

Thanks, can add such detail information at commit message.

Frank

>
> BR,
> Primoz
>
>
>
> >
> > Frank
> >>
> >> Signed-off-by: Primoz Fiser <primoz.fiser@...ik.com>
> >> ---
> >>  arch/arm64/boot/dts/freescale/imx93-phycore-som.dtsi | 1 +
> >>  1 file changed, 1 insertion(+)
> >>
> >> diff --git a/arch/arm64/boot/dts/freescale/imx93-phycore-som.dtsi b/arch/arm64/boot/dts/freescale/imx93-phycore-som.dtsi
> >> index 3d84eed33074..d6589d26c875 100644
> >> --- a/arch/arm64/boot/dts/freescale/imx93-phycore-som.dtsi
> >> +++ b/arch/arm64/boot/dts/freescale/imx93-phycore-som.dtsi
> >> @@ -172,6 +172,7 @@ &usdhc1 {
> >>  	pinctrl-2 = <&pinctrl_usdhc1_200mhz>;
> >>  	bus-width = <8>;
> >>  	non-removable;
> >> +	no-1-8-v;
> >>  	status = "okay";
> >>  };
> >>
> >> --
> >> 2.34.1
> >>
>
> --
> Primoz Fiser
> phone: +386-41-390-545
> email: primoz.fiser@...ik.com
> --
> Norik systems d.o.o.
> Your embedded software partner
> Slovenia, EU
> phone: +386-41-540-545
> email: info@...ik.com