imx8mm custom board some time error -110 whilst initialising SD card

[Dhevan]

Hi,

       I am facing issue on imx8mm custom board.

       if sd card inserted power on the board sd detecting and mounting fine.

       While removing also showing mmc card removed.

       If am again inserting sd card to the slot some time detecting fine but some time showing error as error -110 whilst initialising SD card.

       Why only some time detecting error -110 whilst initialising SD card error ?

       How to solve this issue ?

Thanks & Regards,

         Vasu

[igorpadykov]

Hi Vasu

reason may be ringing on cd signal (like USDHC1_CD_B) so one can try to add

small capacitor on it.

Best regards
igor

[Dhevan]

Hi @igorpadykov,

        Thanks for your reply,

        What does means ringing ?

        Really need to add capacitor on hardware side and what value capacitor we needs to use ?

        If possible do anything on kernel code or device tree file in order to work sd card detect issue.

Thanks & Regards,

        Vasu

[igorpadykov]

>What does means ringing ?

https://en.wikipedia.org/wiki/Ringing_(signal)

Best regards
igor

[Dhevan]

Hi @igorpadykov,

        We have added 10nf capacitor on sd card cd pin but still same issue.

        We have used gpio for card detection not actual sd2_cd pin this makes any issue ?

Thanks & Regards,

        Vasu

[igorpadykov]

Hi Vasu

one can try to debug it using sect.3.3 Debugging  i.MX Porting Guide​

Best regards
igor

[Dhevan]

Hi @igorpadykov 

        If sd card inserted power off and power on the board sd card working fine.

        After board boots remove insert means terminal printing error there where we can put printf for debug.

Thanks & Regards,

        Vasu

[igorpadykov]

all right: "remove insert" may produce more ringing compared with case

" card inserted power off and power on the board".

Best regards
igor

[Dhevan]

Hi @igorpadykov,

         After power off and power on also some time sd card does not detecting.

         If we type mmc dev 1 on uboot commend line sd card detecting in kernel.

         Then voltage showing 1.8v then only sd card working power off and power on.

         Why mmc dev 1 commend only sd card working ?

Thanks & Regards,

       Vasu

[igorpadykov]

Hi Vasu

one can try to run the same image on NXP EVK board to narrow down issue,

if it is caused by hardware or software. If issue could not be reproduced on EVK,

then it is hardware issue with possible bad sd layout. So one can consider relayout custom

board using EVK as example.

Best regards
igor