Reason to stop SD clock while mulch block reading by CMD18

[takayuki_ishii]

Hello community,

Don't you know why SD clock stops while multi block read operation of CMD18?

In customer board, read operation from SD card is missed.

In this time SD clock will be stopped.

So to debug SD card read operation error, we hope to know some trigger to stop SD clock

like some error(CRC error, DMA error etc.) or other reason.

SD card access is used HS mode.

I look forward to hearing from you.

Best regards,

Ishii.

[igorpadykov]

Hi Ishii

reason may be ecc errors caused by power supplies or noisy signals, one can try

to modify drive strength as described in  https://community.nxp.com/t5/i-MX-Processors/eMMC-8GB-to-4GB-crash-on-linux-yocto-boot/m-p/373231

For power supplies one can check  IMX6DQ6SDLHDG, Hardware Development Guide for i.MX 6Quad, 6Dual, 6DualLite, 6Solo Families of Applic...

Table 2-6. Power and decouple recommendations, maximum ripple voltage requirements. 

Best regards
igor

[takayuki_ishii]

Hello Igor,

Thank you for your quick response.

I will talk it with my customer.

Best regards,

Ishii.

[takayuki_ishii]

Hello Igor,

We are still investigating a reson to stop SD_CLK because the issue has not been resolved.

When we checked the error status bit when SD CLK was stopped while multi block read,

a DATA CRC error (uSDHCx_INT_STATUS[DCE]=1) occurred.

In this time, Does SD CLK stop?

We have not yet tried to change the drive strength because we are checking why SD_CLK is stopped.

Best regards,

Ishii

[igorpadykov]

Hi Ishii

>DATA CRC error (uSDHCx_INT_STATUS[DCE]=1) occurred.

>In this time, Does SD CLK stop?

yes this could be reason.

>We have not yet tried to change the drive strength because we are checking why SD_CLK is stopped.

please try to change the drive strength as this may help.

Also one can try with several sd cards.

Best regards
igor

[takayuki_ishii]

Hello Igor,

Thank you for your quick response.

I would be present about DCE bit to my customer.

I think that drive strength will be dealt with after identifying the cause.

Best regards,

Ishii.

[igorpadykov]

> think that drive strength will be dealt with after identifying the cause.

drive strength may be reason of this issue, so please try to change it first.

Best regards
igor