[EXT] Re: [PATCH v2 2/2] imx: Support i.MX91 11x11 FRDM board

[Fabio Estevam]

Hi Joseph,

On Thu, Dec 4, 2025 at 4:12 AM Joseph Guo (OSS) <qijian.guo at oss.nxp.com> wrote:

> Hi Fabio,
>
> USDHC2 is for SD card and its initial stage is at u-boot.
> The IO voltage switch from 3.3v to 1.8v need extra 8ms time on some
> platform. I also tested without this delay, SD card can work as SD3.0 on
> imx91 frdm platform.
>
> I prefer to remain this to avoid potential risk as 91evk 93evk 93frdm
> all remain this property.

I understand that a few NXP boards use this
fsl,signal-voltage-switch-extra-delay-ms property.

Linux does not use it. U-Boot should not use it either. Whatever
solution the kernel applies to provide this delay, let's use it in
U-Boot.

I would really appreciate it if you could investigate this with the
NXP folks and try to remove this custom property from U-Boot.

Let's keep the U-Bot dts files as close as possible with Linux.

I appreciate your understanding and cooperation.

Thanks