IMX8MM Login Prompt hang after debug UART change to UART3

[mahesh_rd]

Hi,

We are working on a custom board based on the i.MX 8M Mini processor. we have designed our board very similar to the i.MX8M Mini Evaluation Kit with little changes which onvolves removal of certain devices like PCIe, SPDIF, MIPI, etc. UART2 is used as debug console in the EVK image, but in our case we have iomuxed it to UART, SPI and several GPIOs.

Since UART2 is used as SPI (via IOMUXing), we decided to redirect debug message console to UART3.

We have made changes in U-Boot SPL and u-boot (imx8mm_evk.h, imx8mm_evk.c, fsl-imx8mm-evk.dts).

We have also changed the same in Linux DTS file (stdout-path=&uart3) and have also passed the following kernel command line parameters

setenv bootargs console=ttymxc2,115200 earlycon=ec_imx6q,0x30880000,115200 root=/dev/mmcblk1p2 rootwait rw

Everything is going well up to this point. I am getting the uboot as well as kernel printk messages. The problem I am facing now is at the login prompt. After it reaches the login prompt the, it stops responding after a few seconds (around 2-3 secs). If I change the debug UART to that of the Evaluation Module (UART2), there is no hang and I can access the console, but with UART3 I get this strange error where it stops responding after a few seconds no matter what I do. I have attached the log of the kernel with uboot.

LOG:

U-Boot SPL 2018.03-01209-gb9dc0ac-dirty (Oct 07 2020 - 10:26:39 +0530)
power_bd71837_init
Mahesh PMIC ChangeDDRINFO: start DRAM init
DRAM PHY training for 3000MTS
check ddr_pmu_train_imem code
check ddr_pmu_train_imem code pass
check ddr_pmu_train_dmem code
check ddr_pmu_train_dmem code pass
Training PASS
DRAM PHY training for 400MTS
check ddr_pmu_train_imem code
check ddr_pmu_train_imem code pass
check ddr_pmu_train_dmem code
check ddr_pmu_train_dmem code pass
Training PASS
DRAM PHY training for 100MTS
check ddr_pmu_train_imem code
check ddr_pmu_train_imem code pass
check ddr_pmu_train_dmem code
check ddr_pmu_train_dmem code pass
Training PASS
DRAM PHY training for 3000MTS
check ddr_pmu_train_imem code
check ddr_pmu_train_imem code pass
check ddr_pmu_train_dmem code
check ddr_pmu_train_dmem code pass
Training PASS
DDRINFO:ddrphy calibration done
DDRINFO: ddrmix config done
Normal Boot
Trying to boot from MMC1


U-Boot 2018.03-01209-gb9dc0ac-dirty (Oct 07 2020 - 10:26:39 +0530)

CPU: Freescale i.MX8MMDL rev1.0 1600 MHz (running at 1200 MHz)
CPU: Industrial temperature grade (-40C to 105C) at 44C
Reset cause: POR
Model: FSL i.MX8MM EVK board
DRAM: 2 GiB
tcpc_init: Can't find device id=0x52
setup_typec: tcpc port2 init failed, err=-19
tcpc_init: Can't find device id=0x50
setup_typec: tcpc port1 init failed, err=-19
MMC: FSL_SDHC: 0, FSL_SDHC: 1
Loading Environment from MMC... *** Warning - bad CRC, using default environment

Failed (-5)
No panel detected: default to MIPI2HDMI
adv7535_init: Can't find device id=0x3d, on bus 1
Display: MIPI2HDMI (1920x1080)
Video: 1920x1080x24
one or more data lanes is not in stop state
dsim pll config failed: -16
Enable DSI bridge failed, err -16
In: serial
Out: serial
Err: serial

BuildInfo:
- ATF
- U-Boot 2018.03-01209-gb9dc0ac-dirty

switch to partitions #0, OK
mmc0 is current device
flash target is MMC:0
Net: No ethernet found.
Fastboot: Normal
Normal Boot
Hit any key to stop autoboot: 2  1  0
switch to partitions #0, OK
mmc0 is current device
** Unable to read file boot.scr **
21965312 bytes read in 942 ms (22.2 MiB/s)
Booting from mmc ...
** Unable to read file fsl-imx8mm-evk.dtb **
WARN: Cannot load the DTB
u-boot=>setenv fdt_file fsl-imx8mm-dfmc.dtb
u-boot=> boot
switch to partitions #0, OK
mmc0 is current device
** Unable to read file boot.scr **
21965312 bytes read in 942 ms (22.2 MiB/s)
Booting from mmc ...
42846 bytes read in 20 ms (2 MiB/s)
## Flattened Device Tree blob at 43000000
Booting using the fdt blob at 0x43000000
Using Device Tree in place at 0000000043000000, end 000000004300d75d

Starting kernel ...

[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 4.14.98+g5910884 (industrialpc@industrialpc) (gcc version 7.3.0 (GCC)) #5 SMP PREEMPT Wed Oct 7 10:34:40 IST 2020
[ 0.000000] Boot CPU: AArch64 Processor [410fd034]
[ 0.000000] Machine model: FSL i.MX8MM EVK board
[ 0.000000] earlycon: ec_imx6q0 at MMIO 0x0000000030880000 (options '115200')
[ 0.000000] bootconsole [ec_imx6q0] enabled
[ 0.000000] efi: Getting EFI parameters from FDT:
[ 0.000000] efi: UEFI not found.
[ 0.000000] Reserved memory: created CMA memory pool at 0x0000000078000000, size 640 MiB
[ 0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool
[ 0.000000] NUMA: No NUMA configuration found
[ 0.000000] NUMA: Faking a node at [mem 0x0000000000000000-0x00000000bfffffff]
[ 0.000000] NUMA: NODE_DATA [mem 0xbffbdb00-0xbffbf8ff]
[ 0.000000] Zone ranges:
[ 0.000000] DMA [mem 0x0000000040000000-0x00000000bfffffff]
[ 0.000000] Normal empty
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000040000000-0x00000000b7ffffff]
[ 0.000000] node 0: [mem 0x00000000b8400000-0x00000000bfffffff]
[ 0.000000] Initmem setup node 0 [mem 0x0000000040000000-0x00000000bfffffff]
[ 0.000000] psci: probing for conduit method from DT.
[ 0.000000] psci: PSCIv1.1 detected in firmware.
[ 0.000000] psci: Using standard PSCI v0.2 function IDs
[ 0.000000] psci: MIGRATE_INFO_TYPE not supported.
[ 0.000000] psci: SMC Calling Convention v1.1
[ 0.000000] percpu: Embedded 21 pages/cpu @ffff80007ff8e000 s48920 r8192 d28904 u86016
[ 0.000000] Detected VIPT I-cache on CPU0
[ 0.000000] CPU features: enabling workaround for ARM erratum 845719
[ 0.000000] Speculative Store Bypass Disable mitigation not required
[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 515072
[ 0.000000] Policy zone: DMA
[ 0.000000] Kernel command line: console=ttymxc2,115200 earlycon=ec_imx6q,0x30880000,115200 root=/dev/mmcblk1p2 rootwait rw
[ 0.000000] PID hash table entries: 4096 (order: 3, 32768 bytes)
[ 0.000000] Memory: 1382496K/2093056K available (12796K kernel code, 1738K rwdata, 5656K rodata, 1216K init, 421K bss, 55200K reserved, 655360K cma-reserved)
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] modules : 0xffff000000000000 - 0xffff000008000000 ( 128 MB)
[ 0.000000] vmalloc : 0xffff000008000000 - 0xffff7dffbfff0000 (129022 GB)
[ 0.000000] .text : 0xffff000008080000 - 0xffff000008d00000 ( 12800 KB)
[ 0.000000] .rodata : 0xffff000008d00000 - 0xffff000009290000 ( 5696 KB)
[ 0.000000] .init : 0xffff000009290000 - 0xffff0000093c0000 ( 1216 KB)
[ 0.000000] .data : 0xffff0000093c0000 - 0xffff000009572a00 ( 1739 KB)
[ 0.000000] .bss : 0xffff000009572a00 - 0xffff0000095dc0c0 ( 422 KB)
[ 0.000000] fixed : 0xffff7dfffe7fb000 - 0xffff7dfffec00000 ( 4116 KB)
[ 0.000000] PCI I/O : 0xffff7dfffee00000 - 0xffff7dffffe00000 ( 16 MB)
[ 0.000000] vmemmap : 0xffff7e0000000000 - 0xffff800000000000 ( 2048 GB maximum)
[ 0.000000] 0xffff7e0000000000 - 0xffff7e0002000000 ( 32 MB actual)
[ 0.000000] memory : 0xffff800000000000 - 0xffff800080000000 ( 2048 MB)
[ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=2, Nodes=1
[ 0.000000] Preemptible hierarchical RCU implementation.
[ 0.000000] RCU restricting CPUs from NR_CPUS=64 to nr_cpu_ids=2.
[ 0.000000] Tasks RCU enabled.
[ 0.000000] RCU: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=2
[ 0.000000] NR_IRQS: 64, nr_irqs: 64, preallocated irqs: 0
[ 0.000000] GICv3: GIC: Using split EOI/Deactivate mode
[ 0.000000] GICv3: no VLPI support, no direct LPI support
[ 0.000000] GICv3: CPU0: found redistributor 0 region 0:0x0000000038880000
[ 0.000000] i.MX8MM clock driver init done
[ 0.000000] arch_timer: cp15 timer(s) running at 8.00MHz (phys).
[ 0.000000] clocksource: arch_sys_counter: mask: 0xffffffffffffff max_cycles: 0x1d854df40, max_idle_ns: 440795202120 ns
[ 0.000003] sched_clock: 56 bits at 8MHz, resolution 125ns, wraps every 2199023255500ns
[ 0.008470] system counter timer init
[ 0.011756] sched_clock: 56 bits at 8MHz, resolution 125ns, wraps every 2199023255500ns
[ 0.019776] clocksource: imx sysctr: mask: 0xffffffffffffff max_cycles: 0x1d854df40, max_idle_ns: 440795202120 ns
[ 0.030961] Console: colour dummy device 80x25
[ 0.034606] Calibrating delay loop (skipped), value calculated using timer frequency.. 16.00 BogoMIPS (lpj=32000)
[ 0.044898] pid_max: default: 32768 minimum: 301
[ 0.049588] Security Framework initialized
[ 0.054167] Dentry cache hash table entries: 262144 (order: 9, 2097152 bytes)
[ 0.061083] Inode-cache hash table entries: 131072 (order: 8, 1048576 bytes)
[ 0.067931] Mount-cache hash table entries: 4096 (order: 3, 32768 bytes)
[ 0.074656] Mountpoint-cache hash table entries: 4096 (order: 3, 32768 bytes)
[ 0.097880] ASID allocator initialised with 32768 entries
[ 0.105882] Hierarchical SRCU implementation.
[ 0.114209] Cannot find MU entry in device tree
[ 0.116006] CPU identified as i.MX8MM, silicon rev 1.0
[ 0.121673] EFI services will not be available.
[ 0.133632] smp: Bringing up secondary CPUs ...
[ 0.161760] Detected VIPT I-cache on CPU1
[ 0.161784] GICv3: CPU1: found redistributor 1 region 0:0x00000000388a0000
[ 0.161812] CPU1: Booted secondary processor [410fd034]
[ 0.161886] smp: Brought up 1 node, 2 CPUs
[ 0.179333] SMP: Total of 2 processors activated.
[ 0.184051] CPU features: detected feature: GIC system register CPU interface
[ 0.191232] CPU features: detected feature: 32-bit EL0 Support
[ 0.197089] CPU features: detected feature: Kernel page table isolation (KPTI)
[ 0.207721] CPU: All CPU(s) started at EL2
[ 0.208980] alternatives: patching kernel code
[ 0.214435] devtmpfs: initialized
[ 0.221577] random: get_random_u32 called from bucket_table_alloc+0x108/0x260 with crng_init=0
[ 0.227852] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
[ 0.237226] futex hash table entries: 512 (order: 4, 65536 bytes)
[ 0.258012] pinctrl core: initialized pinctrl subsystem
[ 0.261619] DMI not present or invalid.
[ 0.264575] NET: Registered protocol family 16
[ 0.270579] vdso: 2 pages (1 code @ ffff000008d06000, 1 data @ ffff0000093c4000)
[ 0.276196] hw-breakpoint: found 6 breakpoint and 4 watchpoint registers.
[ 0.292545] DMA: preallocated 256 KiB pool for atomic allocations
[ 0.296424] Serial: AMBA PL011 UART driver
[ 0.300041] imx rpmsg driver is registered.
[ 0.307303] imx8mm-pinctrl 30330000.pinctrl: initialized IMX pinctrl driver
[ 0.342219] HugeTLB registered 2.00 MiB page size, pre-allocated 0 pages
[ 0.354552] SCSI subsystem initialized
[ 0.362808] usbcore: registered new interface driver usbfs
[ 0.365494] usbcore: registered new interface driver hub
[ 0.370857] usbcore: registered new device driver usb
[ 0.376197] usb_phy_generic usbphynop1: usbphynop1 supply vcc not found, using dummy regulator
[ 0.384814] usb_phy_generic usbphynop2: usbphynop2 supply vcc not found, using dummy regulator
[ 0.397408] bd71837 0-004b: Device ID=0xA1
[ 0.398654] bd71837 0-004b: gpio_intr = 3
[ 0.402782] bd71837 0-004b: chip_irq=49
[ 0.418922] bd71837-pmic bd71837-pmic: regulator register name 'buck1'
[ 0.443063] bd71837-pmic bd71837-pmic: regulator register name 'buck2'
[ 0.467101] bd71837-pmic bd71837-pmic: regulator register name 'buck3'
[ 0.483120] bd71837-pmic bd71837-pmic: regulator register name 'buck4'
[ 0.499149] bd71837-pmic bd71837-pmic: regulator register name 'buck5'
[ 0.515186] bd71837-pmic bd71837-pmic: regulator register name 'buck6'
[ 0.531203] bd71837-pmic bd71837-pmic: regulator register name 'buck7'
[ 0.547239] bd71837-pmic bd71837-pmic: regulator register name 'buck8'
[ 0.563272] bd71837-pmic bd71837-pmic: regulator register name 'ldo1'
[ 0.587314] bd71837-pmic bd71837-pmic: regulator register name 'ldo2'
[ 0.599313] bd71837-pmic bd71837-pmic: regulator register name 'ldo3'
[ 0.623388] bd71837-pmic bd71837-pmic: regulator register name 'ldo4'
[ 0.647419] bd71837-pmic bd71837-pmic: regulator register name 'ldo5'
[ 0.659439] bd71837-pmic bd71837-pmic: regulator register name 'ldo6'
[ 0.680163] bd71837-pmic bd71837-pmic: regulator register name 'ldo7'
[ 0.700194] i2c i2c-0: IMX I2C adapter registered
[ 0.702054] i2c i2c-0: can't use DMA, using PIO instead.
[ 0.704163] BD71837:bd71837_pmic_interrupt() in.
[ 0.707869] i2c i2c-1: IMX I2C adapter registered
[ 0.716191] BD71837:IRQ_WDOG
[ 0.716764] i2c i2c-1: can't use DMA, using PIO instead.
[ 0.719636] BD71837:IRQ_ON_REQ
[ 0.725451] pca953x 2-0020: 2-0020 supply vcc not found, using dummy regulator
[ 0.739455] pca953x 2-0020: failed reading register
[ 0.741847] i2c i2c-2: IMX I2C adapter registered
[ 0.746257] i2c i2c-2: can't use DMA, using PIO instead.
[ 0.752444] media: Linux media interface: v0.10
[ 0.756143] Linux video capture interface: v2.00
[ 0.761015] pps_core: LinuxPPS API ver. 1 registered
[ 0.765738] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it>
[ 0.774948] PTP clock support registered
[ 0.779079] dmi: Firmware registration failed.
[ 0.783872] Advanced Linux Sound Architecture Driver Initialized.
[ 0.789880] Bluetooth: Core ver 2.22
[ 0.793046] NET: Registered protocol family 31
[ 0.797499] Bluetooth: HCI device and connection manager initialized
[ 0.803890] Bluetooth: HCI socket layer initialized
[ 0.808783] Bluetooth: L2CAP socket layer initialized
[ 0.813875] Bluetooth: SCO socket layer initialized
[ 0.819406] clocksource: Switched to clocksource arch_sys_counter
[ 0.824996] VFS: Disk quotas dquot_6.6.0
[ 0.828858] VFS: Dquot-cache hash table entries: 512 (order 0, 4096 bytes)
[ 0.840624] NET: Registered protocol family 2
[ 0.842543] TCP established hash table entries: 16384 (order: 5, 131072 bytes)
[ 0.849602] TCP bind hash table entries: 16384 (order: 6, 262144 bytes)
[ 0.856287] TCP: Hash tables configured (established 16384 bind 16384)
[ 0.862705] UDP hash table entries: 1024 (order: 3, 32768 bytes)
[ 0.868698] UDP-Lite hash table entries: 1024 (order: 3, 32768 bytes)
[ 0.875263] NET: Registered protocol family 1
[ 0.879841] RPC: Registered named UNIX socket transport module.
[ 0.885460] RPC: Registered udp transport module.
[ 0.890180] RPC: Registered tcp transport module.
[ 0.894908] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 0.902065] hw perfevents: enabled with armv8_pmuv3 PMU driver, 7 counters available
[ 0.909437] kvm [1]: 8-bit VMID
[ 0.913032] kvm [1]: GICv3: no GICV resource entry
[ 0.917136] kvm [1]: disabling GICv2 emulation
[ 0.921612] kvm [1]: GIC system register CPU interface enabled
[ 0.927493] kvm [1]: vgic interrupt IRQ1
[ 0.931467] kvm [1]: Hyp mode initialized successfully
[ 0.938636] audit: initializing netlink subsys (disabled)
[ 0.942099] audit: type=2000 audit(0.820:1): state=initialized audit_enabled=0 res=1
[ 0.949972] workingset: timestamp_bits=44 max_order=19 bucket_order=0
[ 0.961465] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[ 0.964971] NFS: Registering the id_resolver key type
[ 0.969574] Key type id_resolver registered
[ 0.973798] Key type id_legacy registered
[ 0.977788] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[ 0.984535] jffs2: version 2.2. (NAND) © 2001-2006 Red Hat, Inc.
[ 0.991015] 9p: Installing v9fs 9p2000 file system support
[ 1.000582] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 244)
[ 1.005176] io scheduler noop registered
[ 1.009225] io scheduler cfq registered (default)
[ 1.014056] io scheduler mq-deadline registered
[ 1.018391] io scheduler kyber registered
[ 1.031350] mxs-dma 33000000.dma-apbh: initialized
[ 1.035213] Bus freq driver module loaded
[ 1.043697] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[ 1.049654] SuperH (H)SCI(F) driver initialized
[ 1.052453] 30860000.serial: ttymxc0 at MMIO 0x30860000 (irq = 28, base_m •hMS’gžc žzlk ž„i0@k)
Iíz 1.064463] console [ttymxc2] enabled
[ 1.064463] console [ttymxc2] enabled
[ 1.068987] bootconsole [ec_imx6q0] disabled
[ 1.068987] bootconsole [ec_imx6q0] disabled
[ 1.078022] 30890000.serial: ttymxc1 at MMIO 0x30890000 (irq = 30, base_baud = 1500000) is a IMX
[ 1.089795] msm_serial: driver initialized
[ 1.097634] imx-drm display-subsystem: no available port
[ 1.108435] loop: module loaded
[ 1.114780] fsl-flexspi 30bb0000.flexspi: n25q00a (131072 Kbytes)
[ 1.122125] slram: not enough parameters.
[ 1.129436] libphy: Fixed MDIO Bus: probed
[ 1.134187] NXP PHY: loading NXP PHY driver: [autonomous mode]
[ 1.140154] tun: Universal TUN/TAP device driver, 1.6
[ 1.145422] CAN device driver interface
[ 1.150851] fec 30be0000.ethernet: 30be0000.ethernet supply phy not found, using dummy regulator
[ 1.159953] pps pps0: new PPS source ptp0
[ 1.167665] fec 30be0000.ethernet (unnamed net_device) (uninitialized): Invalid MAC address: 00:00:00:00:00:00
[ 1.177751] fec 30be0000.ethernet (unnamed net_device) (uninitialized): Using random MAC address: b2:d8:04:1e:3e:ef
[ 1.189326] libphy: fec_enet_mii_bus: probed
[ 1.193702] mdio_bus 30be0000.ethernet-1: MDIO device at address 0 is missing.
[ 1.201341] fec 30be0000.ethernet eth0: registered PHC device 0
[ 1.209488] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[ 1.216042] ehci-platform: EHCI generic platform driver
[ 1.221411] ehci-orion: EHCI orion driver
[ 1.225530] ehci-exynos: EHCI EXYNOS driver
[ 1.229821] ehci-msm: Qualcomm On-Chip EHCI Host Controller
[ 1.235487] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
[ 1.241696] ohci-platform: OHCI generic platform driver
[ 1.247041] ohci-exynos: OHCI EXYNOS driver
[ 1.251703] usbcore: registered new interface driver usb-storage
[ 1.257765] usbcore: registered new interface driver usb_ehset_test
[ 1.264861] usbmisc_imx 32e40200.usbmisc: 32e40200.usbmisc supply vbus-wakeup not found, using dummy regulator
[ 1.275083] usbmisc_imx 32e50200.usbmisc: 32e50200.usbmisc supply vbus-wakeup not found, using dummy regulator
[ 1.286522] input: 30370000.snvs:snvs-powerkey as /devices/platform/30370000.snvs/30370000.snvs:snvs-powerkey/input/input0
[ 1.299382] snvs_rtc 30370000.snvs:snvs-rtc-lp: rtc core: registered 30370000.snvs:snvs-rtc-lp as rtc0
[ 1.309243] i2c /dev entries driver
[ 1.314499] IR NEC protocol handler initialized
[ 1.319121] IR RC5(x/sz) protocol handler initialized
[ 1.324190] IR RC6 protocol handler initialized
[ 1.328856] IR JVC protocol handler initialized
[ 1.333403] IR Sony protocol handler initialized
[ 1.338033] IR SANYO protocol handler initialized
[ 1.342754] IR Sharp protocol handler initialized
[ 1.347471] IR MCE Keyboard/mouse protocol handler initialized
[ 1.353313] IR XMP protocol handler initialized
[ 1.358324] Registered IR keymap rc-empty
[ 1.362414] rc rc0: gpio_ir_recv as /devices/platform/ir-receiver/rc/rc0
[ 1.369220] input: gpio_ir_recv as /devices/platform/ir-receiver/rc/rc0/input1
[ 1.376734] input: MCE IR Keyboard/Mouse (gpio-rc-recv) as /devices/virtual/input/input2
[ 1.387806] Bluetooth: HCI UART driver ver 2.3
[ 1.392273] Bluetooth: HCI UART protocol H4 registered
[ 1.397426] Bluetooth: HCI UART protocol BCSP registered
[ 1.402748] Bluetooth: HCI UART protocol ATH3K registered
[ 1.408160] Bluetooth: HCI UART protocol Three-wire (H5) registered
[ 1.414568] Bluetooth: HCI UART protocol Broadcom registered
[ 1.420243] Bluetooth: HCI UART protocol QCA registered
[ 1.426146] sdhci: Secure Digital Host Controller Interface driver
[ 1.432363] sdhci: Copyright(c) Pierre Ossman
[ 1.436879] Synopsys Designware Multimedia Card Interface Driver
[ 1.443753] sdhci-pltfm: SDHCI platform and OF driver helper
[ 1.450231] mmc1: CQHCI version 5.10
[ 1.453860] sdhci-esdhc-imx 30b50000.mmc: Got CD GPIO
[ 1.503545] mmc1: SDHCI controller on 30b50000.mmc [30b50000.mmc] using ADMA
[ 1.513189] random: fast init done
[ 1.519669] ledtrig-cpu: registered to indicate activity on CPUs
[ 1.526759] caam 30900000.caam: ERA source: CCBVID.
[ 1.534408] caam 30900000.caam: device ID = 0x0a16040100000000 (Era 9)
[ 1.540994] caam 30900000.caam: job rings = 3, qi = 0, dpaa2 = no
[ 1.557302] caam algorithms registered in /proc/crypto
[ 1.565423] caam_jr 30901000.jr0: registering rng-caam
[ 1.570790] caam 30900000.caam: caam pkc algorithms registered in /proc/crypto
[ 1.579579] platform caam_sm: blkkey_ex: 2 keystore units available
[ 1.586166] caam 30900000.caam: SM test passed
[ 1.590991] caam-snvs 30370000.caam-snvs: can't get snvs clock
[ 1.596902] caam-snvs 30370000.caam-snvs: violation handlers armed - non-secure state
[ 1.605261] usbcore: registered new interface driver usbhid
[ 1.610859] usbhid: USB HID core driver
[ 1.618193] ak4458 2-0010: Failed to get supply 'DVDD': -517
[ 1.623904] ak4458 2-0010: Failed to request supplies: -517
[ 1.629747] ak4458 2-0012: Failed to get supply 'DVDD': -517
[ 1.635423] ak4458 2-0012: Failed to request supplies: -517
[ 1.641235] ak4497 2-0011: Failed to get supply 'DVDD': -517
[ 1.646919] ak4497 2-0011: Failed to request supplies: -517
[ 1.652782] ak5558 2-0013: Failed to get supply 'DVDD': -517
[ 1.658479] ak5558 2-0013: Failed to request supplies: -517
[ 1.667251] imx-wm8524 sound-wm8524: failed to find SAI platform device
[ 1.673916] imx-wm8524: probe of sound-wm8524 failed with error -22
[ 1.680752] imx-spdif sound-spdif: ASoC: CPU DAI (null) not registered
[ 1.687320] imx-spdif sound-spdif: snd_soc_register_card failed: -517
[ 1.694039] imx-micfil sound-micfil: failed to find MICFIL platform device
[ 1.700943] imx-micfil: probe of sound-micfil failed with error -22
[ 1.707731] imx-ak4458 sound-ak4458: failed to find SAI platform device
[ 1.714392] imx-ak4458: probe of sound-ak4458 failed with error -22
[ 1.721447] NET: Registered protocol family 26
[ 1.726355] NET: Registered protocol family 10
[ 1.731470] Segment Routing with IPv6
[ 1.735184] NET: Registered protocol family 17
[ 1.739668] mmc1: host does not support reading read-only switch, assuming write-enable
[ 1.743419] can: controller area network core (rev 20170425 abi 9)
[ 1.753936] NET: Registered protocol family 29
[ 1.758407] can: raw protocol (rev 20170425)
[ 1.762698] can: broadcast manager protocol (rev 20170425 t)
[ 1.768398] can: netlink gateway (rev 20170425) max_hops=1
[ 1.774046] Bluetooth: RFCOMM TTY layer initialized
[ 1.778946] Bluetooth: RFCOMM socket layer initialized
[ 1.784108] Bluetooth: RFCOMM ver 1.11
[ 1.787876] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[ 1.793198] Bluetooth: BNEP filters: protocol multicast
[ 1.798439] Bluetooth: BNEP socket layer initialized
[ 1.803418] Bluetooth: HIDP (Human Interface Emulation) ver 1.2
[ 1.809356] Bluetooth: HIDP socket layer initialized
[ 1.814368] lib80211: common routines for IEEE802.11 drivers
[ 1.820074] 9pnet: Installing 9P2000 support
[ 1.824404] Key type dns_resolver registered
[ 1.829180] registered taskstats version 1
[ 1.840911] cpu cpu0: registered imx8mq-cpufreq
[ 1.848293] ak4458 2-0010: Failed to get supply 'DVDD': -517
[ 1.853984] ak4458 2-0010: Failed to request supplies: -517
[ 1.859832] ak4458 2-0012: Failed to get supply 'DVDD': -517
[ 1.865503] ak4458 2-0012: Failed to request supplies: -517
[ 1.871267] ak4497 2-0011: Failed to get supply 'DVDD': -517
[ 1.876936] ak4497 2-0011: Failed to request supplies: -517
[ 1.883669] ak5558 2-0013: Failed to get supply 'DVDD': -517
[ 1.889352] ak5558 2-0013: Failed to request supplies: -517
[ 1.895965] imx-spdif sound-spdif: ASoC: CPU DAI (null) not registered
[ 1.902531] imx-spdif sound-spdif: snd_soc_register_card failed: -517
[ 1.909689] snvs_rtc 30370000.snvs:snvs-rtc-lp: setting system clock to 1970-01-01 00:00:00 UTC (0)
[ 1.919229] WLAN_EN: disabling
[ 1.922935] ALSA device list:
[ 1.925926] No soundcards found.
[ 1.929520] Waiting for root device /dev/mmcblk1p2...
[ 1.939679] mmc1: new ultra high speed SDR104 SDHC card at address aaaa
[ 1.946773] mmcblk1: mmc1:aaaa SC16G 14.8 GiB
[ 1.963592] mmcblk1: p1 p2
[ 1.969813] ak4458 2-0010: Failed to get supply 'DVDD': -517
[ 1.975604] ak4458 2-0010: Failed to request supplies: -517
[ 1.981524] ak4458 2-0012: Failed to get supply 'DVDD': -517
[ 1.987205] ak4458 2-0012: Failed to request supplies: -517
[ 1.993105] ak4497 2-0011: Failed to get supply 'DVDD': -517
[ 1.998790] ak4497 2-0011: Failed to request supplies: -517
[ 2.004688] ak5558 2-0013: Failed to get supply 'DVDD': -517
[ 2.010370] ak5558 2-0013: Failed to request supplies: -517
[ 2.017102] imx-spdif sound-spdif: ASoC: CPU DAI (null) not registered
[ 2.023664] imx-spdif sound-spdif: snd_soc_register_card failed: -517
[ 2.353196] EXT4-fs (mmcblk1p2): recovery complete
[ 2.359824] EXT4-fs (mmcblk1p2): mounted filesystem with ordered data mode. Opts: (null)
[ 2.367957] VFS: Mounted root (ext4 filesystem) on device 179:2.
[ 2.374070] devtmpfs: mounted
[ 2.377388] Freeing unused kernel memory: 1216K
[ 2.471091] systemd[1]: System time before build time, advancing clock.
[ 2.486860] systemd[1]: systemd 237 running in system mode. (+PAM -AUDIT -SELINUX +IMA -APPARMOR +SMACK +SYSVINIT +UTMP -LIBCRYPTSETUP -GCRYPT -GNUTLS +ACL +XZ -LZ4 -SECCOMP +BLKID -ELFUTILS +KMOD -IDN2 -IDN -PCRE2 default-hierarchy=hybrid)
[ 2.508486] systemd[1]: Detected architecture arm64.

Welcome to NXP i.MX Release Distro 4.14-sumo (sumo)!

[ 2.537965] systemd[1]: Set hostname to <imx8dfmc>.
[ 2.545004] random: systemd: uninitialized urandom read (16 bytes read)
[ 2.551678] systemd[1]: Initializing machine ID from random generator.
[ 2.661415] systemd[1]: File /lib/systemd/system/systemd-journald.service:35 configures an IP firewall (IPAddressDeny=any), but the local system does not support BPF/cgroup based firewalling.
[ 2.678541] systemd[1]: Proceeding WITHOUT firewalling in effect! (This warning is only shown for the first loaded unit using IP firewalling.)
[ 2.763653] random: systemd: uninitialized urandom read (16 bytes read)
[ 2.771340] systemd[1]: Created slice System Slice.
[ OK ] Created slice System Slice.
[ 2.787712] random: systemd: uninitialized urandom read (16 bytes read)
[ 2.794563] systemd[1]: Listening on udev Kernel Socket.
[ OK ] Listening on udev Kernel Socket.
[ 2.811732] systemd[1]: Listening on Journal Socket.
[ OK ] Listening on Journal Socket.
[ 2.829641] systemd[1]: Mounting Kernel Debug File System...
Mounting Kernel Debug File System...
Mounting Huge Pages File System...
[ OK ] Listening on udev Control Socket.
Starting udev Coldplug all Devices...
[ OK ] Listening on Network Service Netlink Socket.
Mounting Kernel Configuration File System...
[ OK ] Listening on /dev/initctl Compatibility Named Pipe.
Starting Setup Virtual Console...
[ OK ] Listening on Journal Audit Socket.
[ OK ] Created slice system-getty.slice.
Mounting POSIX Message Queue File System...
[ OK ] Started Forward Password Requests to Wall Directory Watch.
[ OK ] Listening on Journal Socket (/dev/log).
[ OK ] Created slice system-serial\x2dgetty.slice.
[ OK ] Listening on Syslog Socket.
[ OK ] Reached target Swap.
Starting Remount Root and Kernel File Systems...
[ 3.084938] EXT4-fs (mmcblk1p2): re-mounted. Opts: (null)
[ OK ] Reached target Remote File Systems.
Starting Apply Kernel Variables...
[ OK ] Started Dispatch Password Requests to Console Directory Watch.
Starting Journal Service...
Mounting Temporary Directory (/tmp)...
[ OK ] Created slice User and Session Slice.
[ OK ] Reached target Slices.
[ OK ] Reached target Paths.
[ OK ] Started Journal Service.
[ OK ] Mounted Kernel Debug File System.
[ OK ] Mounted Huge Pages File System.
[ OK ] Mounted Kernel Configuration File System.
[ OK ] Started Setup Virtual Console.
[ OK ] Mounted POSIX Message Queue File System.
[ OK ] Started Remount Root and Kernel File Systems.
[ OK ] Started Apply Kernel Variables.
[ OK ] Mounted Temporary Directory (/tmp).
Starting Rebuild Hardware Database...
Starting Create System Users...
Starting Flush Journal to Persistent Storage...
[ OK ] Started udev Coldplug all Devices.
[ 3.420454] systemd-journald[2546]: Received request to flush runtime journal from PID 1
[ OK ] Started Flush Journal to Persistent Storage.
[ OK ] Started Create System Users.
Starting Create Static Device Nodes in /dev...
[ OK ] Started Create Static Device Nodes in /dev.
[ OK ] Reached target Local File Systems (Pre).
[ OK ] Reached target Containers.
Mounting /var/volatile...
[ OK ] Mounted /var/volatile.
Starting Load/Save Random Seed...
[ OK ] Reached target Local File Systems.
Starting Rebuild Dynamic Linker Cache...
Starting Rebuild Journal Catalog...
Starting Create Volatile Files and Directories...
[ OK ] Started Load/Save Random Seed.
[ OK ] Started Rebuild Journal Catalog.
[ OK ] Started Create Volatile Files and Directories.
Starting Run pending postinsts...
Starting Network Time Synchronization...
Starting Update UTMP about System Boot/Shutdown...
[ OK ] Started Update UTMP about System Boot/Shutdown.
[ OK ] Started Run pending postinsts.
[ OK ] Started Rebuild Dynamic Linker Cache.
[ OK ] Started Network Time Synchronization.
[ OK ] Reached target System Time Synchronized.
[ OK ] Started Rebuild Hardware Database.
Starting udev Kernel Device Manager...
Starting Update is Completed...
[ OK ] Started Update is Completed.
[ OK ] Started udev Kernel Device Manager.
Starting Start Psplash Boot Screen...
Starting Network Service...
[ OK ] Reached target System Initialization.
[ OK ] Listening on Avahi mDNS/DNS-SD Stack Activation Socket.
[ OK ] Listening on RPCbind Server Activation Socket.
[ OK ] Started Daily Cleanup of Temporary Directories.
[ OK ] Reached target Timers.
[ OK ] Listening on D-Bus System Message Bus Socket.
[ OK ] Reached target Sockets.
[ OK ] Reached target Basic System.
[ OK ] Started Kernel Logging Service.
[ OK ] Started System Logging Service.
[ OK ] Started Periodic Command Scheduler.
Starting Login Service...
Starting Avahi mDNS/DNS-SD Stack...
[ OK ] Started D-Bus System Message Bus.
[ OK ] Started Login Service.
[ OK ] Started TEE Supplicant.
Starting Telephony service...
[ OK ] Started Network Service.
[ OK ] Started Start Psplash Boot Screen.
[ OK ] Found device /dev/ttymxc2.
[ OK ] Found device /dev/ttymxc1.
[ OK ] Started Avahi mDNS/DNS-SD Stack.
[ OK ] Started Telephony service.
[ OK ] Started Updates psplash to basic.
Starting Network Name Resolution...
[ OK ] Started Network Name Resolution.
[ OK ] Reached target Host and Network Name Lookups.
[ OK ] Reached target Network.
[ OK ] Started Update psplash to network.
Starting Terminate Psplash Boot Screen...
[ OK ] Started Target Communication Framework agent.
Starting Permit User Sessions...
[FAILED] Failed to start Terminate Psplash Boot Screen.
See 'systemctl status psplash-quit.service' for details.
[ OK ] Started Permit User Sessions.
[ OK ] Started Getty on tty1.
[ OK ] Started Serial Getty on ttymxc2.
[ OK ] Started Serial Getty on ttymxc1.
[ OK ] Reached target Login Prompts.
[ OK ] Reached target Multi-User System.
Starting Update UTMP about System Runlevel Changes...
[ OK ] Started Update UTMP about System Runlevel Changes.

NXP i.MX Release Distro 4.14-sumo imx8dfmc ttymxc2

imx8dfmc login: roo


<== END OF KERNEL LOG ==>

[mahesh_rd]

Thanks fro the info, But the problem seemed to be that I had disabled several nodes which were not being used (PCIe, MIPI, CSI, TypeC, etc) and this caused the hang. When I re-enabled them all, he problem seemed to get fixed. I have not singled out  which node is causing this problem, but it has something to do with DTS nodes conflicting.

[b36401]

Please doublecheck the configuration of UART connection on PC side.
Possibly something is going wrong sending data from PC to the board.

[mahesh_rd]

Thanks fro the info, But the problem seemed to be that I had disabled several nodes which were not being used (PCIe, MIPI, CSI, TypeC, etc) and this caused the hang. When I re-enabled them all, he problem seemed to get fixed. I have not singled out which node is causing this problem, but it has something to do with DTS nodes conflicting