linux-kernel - Re: [PATCH 1/8] ARM: dts: microchip: sam9x60_curiosity: Add power-supply properties for sdmmc nodes

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Message-ID: <76ccbfd5-ed5e-4443-b741-d7b2e90f6c18@tuxon.dev>
Date: Sat, 3 Feb 2024 18:55:30 +0200
From: claudiu beznea <claudiu.beznea@...on.dev>
To: Mihai.Sain@...rochip.com, krzysztof.kozlowski@...aro.org,
 robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
 Nicolas.Ferre@...rochip.com, alexandre.belloni@...tlin.com,
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/8] ARM: dts: microchip: sam9x60_curiosity: Add
 power-supply properties for sdmmc nodes

Hi, Mihai,

On 23.01.2024 11:07, Mihai.Sain@...rochip.com wrote:
> Hi Krzysztof,
> 
> I'm sorry for quoting (email is sent from Outlook).
> The sdmmc controller from SAM9 MPUs doesn't support the IO voltage signaling/switching required by the UHS sd-card.
> On the electrical schematics of the boards the controller and sd-card power pins are connected to 3V3 regulator.
> On the SAMA5 MPUs there is support for IO voltage switching but since we have issues with the tuning procedure required but the UHS cards,
> we want to keep vqmmc at 3V3 in order to use high-speed mode.

Can you capture this information in each patch description?

> 
> Best regards,
> Mihai Sain
> 
> ----------------------------------------------------------------------
> 
>> diff --git a/arch/arm/boot/dts/microchip/at91-sam9x60_curiosity.dts 
>> b/arch/arm/boot/dts/microchip/at91-sam9x60_curiosity.dts
>> index c6fbdd29019f..457c54dde0b7 100644
>> --- a/arch/arm/boot/dts/microchip/at91-sam9x60_curiosity.dts
>> +++ b/arch/arm/boot/dts/microchip/at91-sam9x60_curiosity.dts
>> @@ -452,6 +452,8 @@ &sdmmc0 {
>>       pinctrl-0 = <&pinctrl_sdmmc0_default &pinctrl_sdmmc0_cd>;
>>       cd-gpios = <&pioA 25 GPIO_ACTIVE_LOW>;
>>       disable-wp;
>> +     vmmc-supply = <&vdd1_3v3>;
>> +     vqmmc-supply = <&vdd1_3v3>;
> 
> For this and all other patches:
> 
> It is surprising that you use the same supply for both. Looks like inaccurate description. It is possible, but I think unlikely because usually VQMMC has lower voltage than 3.3V.
> 
> Best regards,
> Krzysztof
>