Some UHS card cannot work on imx8-evk

[mileswang]

Dear sir,

We found some UHS card cannot work in SDR104 on imx8-evk. Sometimes tuning failed, sometimes not command response from card after tuing. All card work OK in high speed mode. We want to know your UHS card test results on imx8-evk.

Below information is from TI for your reference. Do you have similar testing information to share?

http://processors.wiki.ti.com/index.php/Linux_Core_MMC/SD_User%27s_Guide#Testing_Information

Testing Information

FUNCTIONAL UHS CARDS
STRONTIUM NITRO 466x UHS CARD
SANDISK EXTREME UHS CARD
SANDISK ULTRA UHS CARD
SAMSUNG EVO+ UHS CARD
SAMSUNG EVO UHS CARD
KINGSTON UHS CARD (DDR mode)
TRANSCEND PREMIUM 400X UHS CARD (Non fatal error and then it re-enumerates in UHS mode)

FUNCTIONAL (WITH LIMITED CAPABILITY) UHS CARD
SONY UHS CARD - Voltage switching fails and enumerates in high speed
GSKILL UHS CARD - Voltage switching fails and enumerates in high speed
PATRIOT 8G UHS CARD - Voltage switching fails and enumerates in high speed

Best regards,

Miles

[igorpadykov]

Hi Miles

unfortunately I am not aware of such testing informatio, however

tuning failures usually are caused by signal integrity, which may be improved

by adjusting drive strength, for example using sect.8.2.4.192 SW_PAD_CTL_PAD_SD1_

DATA0 SW PAD Control Register (IOMUXC_SW_PAD_CTL_PAD_SD1_DATA0)

i.MX8MDQ Reference Manual
https://www.nxp.com/docs/en/reference-manual/IMX8MDQLQRM.pdf

Note SD drive strength also can be changed, it is described in sect.6.7 Driver Strength

and Bus Timing for 1.8V Signaling SD 3.0 Physical Layer Specification.

Best regards
igor
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[mileswang]

Thanks,

Current configurations as below:

IOMUXC_SW_PAD_CTL_PAD_SD2_CLK = 0x87

IOMUXC_SW_PAD_CTL_PAD_SD2_CMD = 0xc7

IOMUXC_SW_PAD_CTL_PAD_SD2_DATA0-4 = 0xc7

current limit = 800mA

driver strength = TypeB (default)

Is it OK?

[igorpadykov]

settings may depend on used sd card, suggest to check waveforms and signal timings

with oscilloscope with each card and adjust iomux settings accordingly.

Best regards
igor