STM32MP157 – SD card works in ROM/TF-A (FSBL) but fails in U-Boot with CMD55 retries

[Najib Kassab]

 

Problem description

I have a custom board based on STM32MP157FAA.
The SD card boots perfectly in:

• ROM boot

• TF-A BL2 (FSBL)

But once control reaches U-Boot, the SD card becomes completely unusable and U-Boot shows continuous:

 

stm32_sdmmc2 mmc@58005000: cmd 55 failed, retrying ...

U-Boot cannot read environment, cannot rescan the card, and reports “No block device”.

This is very confusing because the same SD card and hardware clearly work during ROM and TF-A stages.

---

Boot log

TF-A / BL2 (working)

INFO: Using SDMMC INFO: Instance 1 INFO: Boot used partition fsbl1 ... INFO: BL2: Loading image id 5 NOTICE: BL2: Booting BL32

No SD errors at all.

U-Boot (failing)

U-Boot 2023.10-stm32mp-r2
MMC: STM32 SD/MMC: 0, STM32 SD/MMC: 1
Loading Environment from MMC...
stm32_sdmmc2 mmc@58005000: cmd 55 failed, retrying ...
*** Warning - No block device, using default environment ...
Saving Environment to MMC... No block device

Also in U-Boot:

Clocks:
- MPU : 0 MHz
- MCU : 0 MHz
- AXI : 0 MHz
- PER : 0 MHz
- DDR : 0 MHz

---

Hardware notes

• No external level shifter

• No SD direction pin used

• SD is wired directly to SDMMC1

• Fixed 3.3V I/O

• No card detect pin

---

Linux / TF-A SDMMC1 DTS (works)

 

&sdmmc1 {
status = "okay";
bus-width = <4>;
no-1-8-v;
vmmc-supply = <&vdd_sd>;
disable-wp;
broken-cd; };

PMIC regulator:

vdd_sd:ldo5{
regulator-name = "vdd_sd";
regulator-min-microvolt = <2900000>;
regulator-max-microvolt = <2900000>;
regulator-boot-on;
};

 

 

No special SDMMC settings exist in the *-u-boot.dtsi.

You can check the included log for more infomations

[PatrickF]

Hi,

---

@Najib Kassab wrote:

Also in U-Boot:

Clocks:
- MPU : 0 MHz
- MCU : 0 MHz
- AXI : 0 MHz
- PER : 0 MHz
- DDR : 0 MHz

---

 

---

that's very strange to have all clocks stated at 0 with uBoot. Maybe root cause of failing SDMMC access.

As far as I know, BootROM and TF-A uses default SDMMC settings while uBoot reconfigure SDMMC according to Device Tree. Maybe an issue with OpTee which manage the clocks after TF-A.

 

Regards.

[Najib Kassab]

@PatrickF 

 

So what do you suggest to do now , if the problem is with optee?