How can I get the MMC timing spec higher than sd high-speed?

[Tomáš Juřena]

Hello,

I am having difficulties with the MMC bus and the external SDIO wifi module. We are using the wifi module jody-w263 from U-blox with the OSD32MP1, and the communication with the module works, but it is quite slow. The wifi module is capable of SDR 104 and DDR50 communication speeds, but I add the support to the DTS, the communication is broken and the device returns the -110 while initializing.

How can I add support for higher speeds?

I attach the working dts, dmesg, ios and caps, and relevant schematic.

Any suggestion will be appreciated.

Best regards,

Tomáš.

[Tomáš Juřena]

I think that the rate for the mmc3 is correct.

[Tomáš Juřena]

I did not make any modifications except the DTS, defconfig, and disabling the code inside of the sdmmc_vswitch. I only hope that I did not send you logs, that contains some of my debug messages that could mislead you.

I am attaching the bbappend file for the linux-stm32mp_5.4 and manifest file to check that the versions match.

[Bernard PUEL]

yes it is.

[Bernard PUEL]

Next step for us is to to send you a debug patch to better see what really happens (between the mmc framework and the regulator framework). So if you confirm you are on 5.4.56 except for the stm32 sdmmc drivers. We can proceed.

[Tomáš Juřena]

Yes, the only change is the sdmmc_vswitch, but I can revert it anytime.

[Bernard PUEL]

Hello Tomas,

your yocto setup looks good.

Could you please:

• revert "sdmmc_vswitch" hack
• apply previous dts config:

vmmc-supply = <&v3v3>;

sd-uhs-ddr50;

vqmmc-supply = <&v1v8_ldo1>;

mmc-pwrseq = <&wifi_pwrseq>;

/* USER CODE END sdmmc3 */

• activate dyn trace:

root=PARTUUID=e91c4e10-16e6-4c0e-bd0e-77becf4a3582 rootwait rw console=ttySTM0,115200 loglevel=8 dyndbg="file drivers/mmc/* +p"

• apply the attached debug patch

And send us back the log of the boot.

Thanks in advanced.

[Tomáš Juřena]

Hi Bernard,

I have done what you asked for and here is the log. I hope it helps to identify the issue.

[Bernard PUEL]

Hello Tomas,

Could you please apply these 3 patches as a tentative correction ? You can keep the debug patch + dyn trace on a first step.