TQMa8MxML: Problem boot from some micro SD cards #4
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Hi, (Edit: fixed commit reference, accidentally got the TQMa8MPxL instead of TQMa8MxML version of the fix at first) |
Thank you for your prompt reply. Currently, we are working with the kirkstone.TQMa8MxML.BSP.SW.0091 release (current branch: TQMa8-v2020.04_imx_5.4.70_2.3.0) . We’ve tried cherry-picking the commit 19e90b5, but the issue persists when testing on the hardware. Any suggestions would be appreciated. |
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Hmm, that is unfortunate. The errors we were seeing (also with certain SanDisk SD cards) looked extremely similar, with the card stopping to respond to certain commands after an incomplete reset, resulting in error 110 (ETIMEDOUT) - although I don't remember the error 70 (ECOMM) happening here. However, I think that our issue happened earlier in the boot - as the reset in the SPL was to short, loading the U-Boot proper failed, instead of U-Boot failing to load the OS. Some things to try:
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We had a similar sounding problem - U-Boot came up but U-Boot proper could nor read from SD-Card. But the error was seen only on one board for exactly one card type. It was blamed on this board. At this time we picked some patches that correct several issues in the USDHC controller driver and as far as I can tell the problem was solved on this board, too. I rebased and pushed the patches to branch `testing/v2020.04-imx-sd-card-fixes. |
Thank you for the suggestions. Here's what we've tried so far:
The i.MX8M Mini can support high-speed grades in the USDHC controllers. Turning off the corresponding configuration option for the TQMa8MxML variant in Kconfig before booting the kernel seems to resolve the issue. Additionally, we tried capping the USDHC controller's capabilities by disabling the sd-uhs-sdr104 flag in imx8mm-mba8mx-u-boot.dtsi. Surprisingly, this also resolves the issue. I'm still curious why limiting the USDHC controller's capabilities in this way helps. From what I understand, the generic MMC driver uses these flags to set the host capabilities. If anyone has insights into why reducing the speed grades seems to improve stability, I would appreciate your input. |
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Hello, disabling |
Hi, Compiling U-Boot based on the testing/v2020.04-imx-sd-card-fixes branch did not resolve the issue. => mmc dev 1
Card did not respond to voltage select!However, disabling either MMC_UHS_SUPPORT (preventing the SD Host controller to try to move to UHS modes) or sd-uhs-sdr104 resolved the issue. => mmc dev 1
switch to partitions #0, OK
mmc1 is current device
=> mmc info
Device: FSL_SDHC
Manufacturer ID: 3
OEM: 5344
Name: SH32G
Bus Speed: 50000000
Mode: SD High Speed (50MHz)
Rd Block Len: 512
SD version 3.0
High Capacity: Yes
Capacity: 29.7 GiB
Bus Width: 4-bit
Erase Group Size: 512 Bytes |
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Hello, this means, that after successful detecting the card and reading card data switching to the lower 1.8 V IO Voltage which is needed for UHS modes did not succeed. Does this happen on an MBa8Mx (EVK) or on a custom mainboard? |
Hi, We are using a custom main board based on the TQMa8MxML SOM revision 0200. I reviewed the previous U-Boot traces and the CMD11 appears as follows: CMD_SEND:11
ARG 0x00000000
Run CMD11 1.8V switch
MMC_RSP_R1,5,6,7 0x00000320 |
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Hello, since the SD Card issue occurs on a custom specific baseboard, can you please contact us at [email protected] |
We have not yet received an email from you, has the issue been resolved in the meantime? |
Thank you for following up. I haven't sent an email yet as I'm still in the process of running some tests. Although the issue occurs on a custom baseboard, it is based on the TQMa8MxML SOM variant and involves the Yocto-based BSP (specifically the U-Boot component) maintained by TQM. Therefore, I believe it's still relevant to continue the technical discussion here. I also appreciate the valuable input from @tq-niebelm and @tq-schifferm. I'll reach out via email if direct support is needed. |
Hi everyone,
We are experiencing boot issues with our embedded module TQMa8MxML when using certain micro SD cards, specifically the SanDisk MAX ENDURANCE microSD™ Card - 32GB Class 10.
The u-boot fails to load the Device Tree Blob from the micro SD card, resulting in the error message: 'WARN: Cannot load the DT!'. The boot log below illustrates the failure after enabling #define CONFIG_MMC_TRACE.
Does anyone have any insights into why this might be occurring?
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