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Linux/AM3358: Last line we see is "Waiting for root device /dev/mmcblk0p2"

Brian Weir
Intellectual 810 points
Part Number: AM3358


Tool/software: Linux

We have been stuck here for three days.  We have tried several patches and device tree settings per the Sitara Forum.  Supposedly looking for the root file system, but I don't know what specifically in the root file system it is looking for.  I think our boot log looks good it is attached to https://e2e.ti.com/support/arm/sitara_arm/f/791/t/579502  We have tried using an alternate SD Card Detect input (SDCD) and tying it low (and high) to no avail.

We have tried several root file systems:  using create_sdcard.sh, Umbuntu, a home grown one we built for an older board, etc. 

So what else could we try?  Possibly a different boot device? Is there a way to test the SD Card's ext4 root partition using U-Boot or in the kernel prior to this point?

Need some help.

Regards,

Brian Weir

  

  • 0
    Intellectual 810 points
    Reference "Waiting for root device /dev/mmcblk0p2" not being able to boot to the SD Card Root File system, I am able to do file lists of the SD card ext partition using U-Boot commands: ext2ls mmc 0:2 or for a specific folder ext2ls mmc 0:2 /sbin

    For some reason when the kernel goes out to find the file system, it can't find it.

    Perhaps I am using the wrong file system type? should it be ext2 , ext3, ext4, other?

    Thanks, Brian
  • 0 in reply to Brian Weir
    Intellectual 810 points
    We have redirected uenv.txt to point the kernel to /dev/sda1 and boot to a usb stick that only contained the root file system. The u-boot, kernel, and device tree are still on the sd card. This seems to work correctly but the kernel is still unable to see the sd card /dev/.

    What have we missed in either the device tree or kernel configuration or....?

    Thanks, Brian
  • 0 in reply to Brian Weir
    TI__Guru**** 170625 points
    Hi Brian,

    Do you use AM335x TI PSDK? If yes, which version?

    In the latest PSDK, ext3 is used:

    ti-processor-sdk-linux-am335x-evm-03.02.00.05/bin/create-sdcard.sh

    processors.wiki.ti.com/.../Processor_SDK_Linux_create_SD_card_script
    processors.wiki.ti.com/.../Processor_SDK_Linux_Filesystem
    processors.wiki.ti.com/.../Sitara_Linux_SDK_Creating_a_SD_Card_with_Linux


    Regards,
    Pavel
  • 0 in reply to Pavel Botev
    Intellectual 810 points
    Pavel, Thank you for the post.

    We did however find our problem yesterday, we are able to boot to the Root File System from the SD Card without the SD_CD line connected.

    it turned out to be a problem in the mmc device tree:

    This patch fixed it:
    &mmc1 {
    status = "okay";
    - vqmmc-supply = <&ldo3_reg>;
    - vmmc-supply = <&ldo4_reg>;
    + vmmc-supply = <&ldo3_reg>;
    bus-width = <0x4>;
    - pinctrl-names = "default"; /*, "sleep";*/
    - pinctrl-0 = <&sd_card_pins_default>;
    - /*pinctrl-1 = <&sd_card_pins_sleep>;*/
    - /*no-1-8-v;*/
    - /*broken-cd;*/
    - cd-gpios = <&gpio0 6 GPIO_ACTIVE_HIGH>;
    };

    I don't understand it though and would like an explanation of the line: vmmc-supply = <&ldo3_reg>;

    Is &ldo3_reg referring to the PMIC LDO3? LDO3 is a 1.8v supply. The SD Card is a 3.3v device, powered at 3.3v, so, I’m a little confused. Does this change suggest the SD Card MMC interface run at 1.8v?

    Thanks and Regards, Brian
  • 0 in reply to Brian Weir
    TI__Guru**** 170625 points
    Brian,

    Do you use AM335x TI PSDK? If yes, which version?

    From the HW side, MMCSD has Dedicated Power Rail for 1.8‐V or 3.3-V Operation.

    In AM335x TI PSDK we have:

    &mmc1 {
    vmmc-supply = <&vmmc_reg>;
    pinctrl-0 = <&mmc1_pins>;
    cd-gpios = <&gpio0 6 GPIO_ACTIVE_LOW>;
    }

    &tps {
    regulators {
    vmmc_reg: regulator@12 {
    regulator-min-microvolt = <1800000>;
    regulator-max-microvolt = <3300000>;
    regulator-always-on;
    };

    Regards,
    Pavel