HS400 strobe DLL status REF not lock! on eMMC

[benjaminblanton]

Hi,  I just received a new spin of boards with the latest D revision the IMX7D and have am having an issue with several boards.  In the past we always saw this set of warning pop up:

sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status REF not lock!
sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status SLV not lock!

but now we see this multiple times with IO errors and our linux image will not boot from Flash.  It doesnt happen always, maybe 50% of the time. 

Can anyone help with this?

sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status REF not lock!
sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status SLV not lock!
sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status REF not lock!
sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status SLV not lock!
sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status REF not lock!
sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status SLV not lock!
sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status REF not lock!
sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status SLV not lock!
sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status REF not lock!
sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status SLV not lock!
sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status REF not lock!
sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status SLV not lock!
sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status REF not lock!
sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL status SLV not lock!
print_req_error: I/O error, dev mmcblk1, sector 0 flags 0

[benjaminblanton]

Hi Igor,

It looks like there is a kernal update related to a delay on the data strobe that fixes this issue.

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?h=next-20191009&id=2eaf5...

[igorpadykov]

Hi Benjamin

reason may be additional board noise on some boards, one can try to

tweak emmc drive strength using DSE field iomux pad register, like IOMUXC_SW_PAD_CTL_PAD_SD3_DATA1.

Also may be useful to check board power supplies for noise, pay attention to ripple requirement

described in Hardware Development Guide for i.MX7Dual and 7Solo Applications Processors

Best regards
igor
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------