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: <cffdcd6c-88c5-43c1-9f00-d1c84af73f4c@norik.com>
Date: Fri, 11 Apr 2025 08:51:18 +0200
From: Primoz Fiser <primoz.fiser@...ik.com>
To: Frank Li <Frank.li@....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

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.

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