Re: [PATCH 1/1] arm64: dts: rockchip: default to host mode for USB on Radxa E25

[Jonas Karlman <jonas@kwiboo.se>]

On 2024-12-23 04:00, Chukun Pan wrote:
> Hi,
>> I've been using the uSD card for a long time as a bootloader only,
>> so I don't know what the problem is.
>>
>> Do you have any information on how to reproduce the problem?
>>
>> Best regards,
> 
> Not stable on openwrt/lede, sometimes falling to sd-highspeed.
> Maybe it would be better to switch to sd-uhs-sdr50 mode.

I would advise against using any sd-uhs- mode for sd-card on Rockchip
RK356x boards because of a timing issue during boot between mmc,
regulator and IO-domain drivers.

Any board that support changing between 1v8 or 3v3 io-voltage for the
sd-card is possible affected.

There is a race condition during boot and when IO-domain driver has not
been probed before UHS tuning is started the tuning is done using a 3v3
IO-domain configuration instead of 1v8.

This can typically be seen by comparing UHS tuning during boot and when
same sd-card is removed and re-inserted after boot.

Ideally this race condition should be solved instead of limiting use
of UHS modes. However, use of sd-uhs-sdr50 is typically more forgiving
and has been used on other boards.

Regards,
Jonas

> 
> Thanks,
> Chukun
>