USB: why USB devices the modules automatically loaded
I have am335x related customized board and kernel(4.4.16) source code I configure the FTDI module driver. so after kernel start successfully I attach ftdi converter to usb port and then type lsmod command to check module list
Module Size Used by Not tainted
cp210x 15164 0
usbserial 34545 1 cp210x
bridge 87777 0
stp 2111 1 bridge
llc 5184 2 bridge,stp
usb_f_rndis 21887 2
usb_f_ecm 9211 2
u_ether 11816 2 usb_f_rndis,usb_f_ecm
libcomposite 42715 16 usb_f_rndis,usb_f_ecm
musb_dsps 9418 0
musb_hdrc 72752 1 musb_dsps
omap_aes_driver 19511 0
omap_sham 22202 0
omap_rng 4212 0
rng_core 7198 1 omap_rng
musb_am335x 1547 0 [permanent]
How usb serial module(cp210x) load automatically ??
I share dmesg log ( FTDI converter connect)
root@arm:~# dmesg
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Initializing cgroup subsys cpuset
[ 0.000000] Initializing cgroup subsys cpu
[ 0.000000] Initializing cgroup subsys cpuacct
[ 0.000000] Linux version 4.4.16 (hiten@hi10) (gcc version 5.4.0 20160609 (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.9) ) #1 SMP PREEMPT RT Fri Jul 10 12:56:15 IST 2020
[ 0.000000] CPU: ARMv7 Processor [413fc082] revision 2 (ARMv7), cr=50c5387d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[ 0.000000] Machine model: TI AM335x BeagleBone Black
[ 0.000000] cma: Reserved 24 MiB at 0x9e000000
[ 0.000000] Memory policy: Data cache writeback
[ 0.000000] On node 0 totalpages: 130816
[ 0.000000] free_area_init_node: node 0, pgdat c0ab8c00, node_mem_map dfa6d000
[ 0.000000] Normal zone: 1150 pages used for memmap
[ 0.000000] Normal zone: 0 pages reserved
[ 0.000000] Normal zone: 130816 pages, LIFO batch:31
[ 0.000000] CPU: All CPU(s) started in SVC mode.
[ 0.000000] AM335X ES2.1 (neon )
[ 0.000000] PERCPU: Embedded 13 pages/cpu @dfa2b000 s21408 r8192 d23648 u53248
[ 0.000000] pcpu-alloc: s21408 r8192 d23648 u53248 alloc=13*4096
[ 0.000000] pcpu-alloc: [0] 0
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 129666
[ 0.000000] Kernel command line: console=ttyS0,115200 mem=511M bootlogo=9FF00000 fbcon=rotate:1 root=/dev/mmcblk1p2 rootfstype=ext4 rw rootwait verify=n lpj=1990656 quiet
[ 0.000000] PID hash table entries: 2048 (order: 1, 8192 bytes)
[ 0.000000] Dentry cache hash table entries: 65536 (order: 7, 524288 bytes)
[ 0.000000] Inode-cache hash table entries: 32768 (order: 5, 131072 bytes)
[ 0.000000] Memory: 481260K/523264K available (6874K kernel code, 427K rwdata, 3432K rodata, 316K init, 697K bss, 17428K reserved, 24576K cma-reserved, 0K highmem)
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB)
[ 0.000000] fixmap : 0xffc00000 - 0xfff00000 (3072 kB)
[ 0.000000] vmalloc : 0xe0000000 - 0xff800000 ( 504 MB)
[ 0.000000] lowmem : 0xc0000000 - 0xdff00000 ( 511 MB)
[ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB)
[ 0.000000] modules : 0xbf800000 - 0xbfe00000 ( 6 MB)
[ 0.000000] .text : 0xc0008000 - 0xc0a18d40 (10308 kB)
[ 0.000000] .init : 0xc0a19000 - 0xc0a68000 ( 316 kB)
[ 0.000000] .data : 0xc0a68000 - 0xc0ad2f60 ( 428 kB)
[ 0.000000] .bss : 0xc0ad5000 - 0xc0b8376c ( 698 kB)
[ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.000000] Preemptible hierarchical RCU implementation.
[ 0.000000] Build-time adjustment of leaf fanout to 32.
[ 0.000000] RCU restricting CPUs from NR_CPUS=2 to nr_cpu_ids=1.
[ 0.000000] RCU: Adjusting geometry for rcu_fanout_leaf=32, nr_cpu_ids=1
[ 0.000000] NR_IRQS:16 nr_irqs:16 16
[ 0.000000] IRQ: Found an INTC at 0xfa200000 (revision 5.0) with 128 interrupts
[ 0.000000] OMAP clockevent source: timer2 at 24000000 Hz
[ 0.000012] sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 89478484971ns
[ 0.000025] clocksource: timer1: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 79635851949 ns
[ 0.000031] OMAP clocksource: timer1 at 24000000 Hz
[ 0.000699] clocksource_probe: no matching clocksources found
[ 0.000864] Console: colour dummy device 80x30
[ 0.001029] Calibrating delay loop (skipped) preset value.. 995.32 BogoMIPS (lpj=1990656)
[ 0.001034] pid_max: default: 32768 minimum: 301
[ 0.001139] Security Framework initialized
[ 0.001146] Yama: becoming mindful.
[ 0.001174] AppArmor: AppArmor disabled by boot time parameter
[ 0.001207] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.001212] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.001950] Initializing cgroup subsys io
[ 0.001968] Initializing cgroup subsys memory
[ 0.002000] Initializing cgroup subsys devices
[ 0.002011] Initializing cgroup subsys freezer
[ 0.002021] Initializing cgroup subsys net_cls
[ 0.002030] Initializing cgroup subsys perf_event
[ 0.002038] Initializing cgroup subsys net_prio
[ 0.002048] Initializing cgroup subsys pids
[ 0.002146] CPU: Testing write buffer coherency: ok
[ 0.002508] CPU0: thread -1, cpu 0, socket -1, mpidr 0
[ 0.002644] Setting up static identity map for 0x80008240 - 0x8000828c
[ 0.035264] Brought up 1 CPUs
[ 0.035289] SMP: Total of 1 processors activated (995.32 BogoMIPS).
[ 0.035296] CPU: All CPU(s) started in SVC mode.
[ 0.036747] devtmpfs: initialized
[ 0.059499] VFP support v0.3: implementor 41 architecture 3 part 30 variant c rev 3
[ 0.078583] omap_hwmod: debugss: _wait_target_disable failed
[ 0.133203] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
[ 0.136912] pinctrl core: initialized pinctrl subsystem
[ 0.138947] NET: Registered protocol family 16
[ 0.142301] DMA: preallocated 256 KiB pool for atomic coherent allocations
[ 0.155201] cpuidle: using governor ladder
[ 0.167193] cpuidle: using governor menu
[ 0.172759] OMAP GPIO hardware version 0.1
[ 0.173271] GPIO line 61 (EMMC ResetN) hogged as output/high
[ 0.185683] No ATAGs?
[ 0.185711] hw-breakpoint: debug architecture 0x4 unsupported.
[ 0.236748] edma 49000000.edma: TI EDMA DMA engine driver
[ 0.241697] SCSI subsystem initialized
[ 0.242030] usbcore: registered new interface driver usbfs
[ 0.242101] usbcore: registered new interface driver hub
[ 0.242255] usbcore: registered new device driver usb
[ 0.242759] pps_core: LinuxPPS API ver. 1 registered
[ 0.242769] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it>
[ 0.242800] PTP clock support registered
[ 0.243769] omap-mailbox 480c8000.mailbox: omap mailbox rev 0x400
[ 0.248208] Bluetooth: Core ver 2.21
[ 0.248263] NET: Registered protocol family 31
[ 0.248271] Bluetooth: HCI device and connection manager initialized
[ 0.248289] Bluetooth: HCI socket layer initialized
[ 0.248302] Bluetooth: L2CAP socket layer initialized
[ 0.248360] Bluetooth: SCO socket layer initialized
[ 0.251264] NetLabel: Initializing
[ 0.251276] NetLabel: domain hash size = 128
[ 0.251282] NetLabel: protocols = UNLABELED CIPSOv4
[ 0.251341] NetLabel: unlabeled traffic allowed by default
[ 0.252067] clocksource: Switched to clocksource timer1
[ 0.265931] NET: Registered protocol family 2
[ 0.266738] TCP established hash table entries: 4096 (order: 2, 16384 bytes)
[ 0.266797] TCP bind hash table entries: 4096 (order: 4, 114688 bytes)
[ 0.266919] TCP: Hash tables configured (established 4096 bind 4096)
[ 0.266996] UDP hash table entries: 256 (order: 2, 16384 bytes)
[ 0.267027] UDP-Lite hash table entries: 256 (order: 2, 16384 bytes)
[ 0.267253] NET: Registered protocol family 1
[ 0.271871] RPC: Registered named UNIX socket transport module.
[ 0.271886] RPC: Registered udp transport module.
[ 0.271893] RPC: Registered tcp transport module.
[ 0.271900] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 0.273009] hw perfevents: enabled with armv7_cortex_a8 PMU driver, 5 counters available
[ 0.275531] futex hash table entries: 256 (order: 2, 16384 bytes)
[ 0.275650] audit: initializing netlink subsys (disabled)
[ 0.275729] audit: type=2000 audit(0.272:1): initialized
[ 0.290633] zbud: loaded
[ 0.291309] VFS: Disk quotas dquot_6.6.0
[ 0.291584] VFS: Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[ 0.299866] NFS: Registering the id_resolver key type
[ 0.299928] Key type id_resolver registered
[ 0.299937] Key type id_legacy registered
[ 0.299973] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[ 0.299989] Installing knfsd (copyright (C) 1996 okir@monad.swb.de).
[ 0.300916] jffs2: version 2.2. (NAND) (SUMMARY) �© 2001-2006 Red Hat, Inc.
[ 0.301791] fuse init (API version 7.23)
[ 0.316180] gfs2: GFS2 installed
[ 0.316682] ceph: loaded (mds proto 32)
[ 0.322967] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 249)
[ 0.327217] io scheduler noop registered
[ 0.327235] io scheduler deadline registered
[ 0.327519] io scheduler cfq registered (default)
[ 0.329111] pinctrl-single 44e10800.pinmux: 142 pins at pa f9e10800 size 568
[ 0.332836] wkup_m3_ipc 44e11324.wkup_m3_ipc: could not get rproc handle
[ 0.334316] Serial: 8250/16550 driver, 6 ports, IRQ sharing disabled
[ 0.337613] console [ttyS0] disabled
[ 0.337700] 44e09000.serial: ttyS0 at MMIO 0x44e09000 (irq = 158, base_baud = 3000000) is a 8250
[ 0.350727] console [ttyS0] enabled
[ 0.351614] 481a8000.serial: ttyS4 at MMIO 0x481a8000 (irq = 159, base_baud = 3000000) is a 8250
[ 0.352530] 481aa000.serial: ttyS5 at MMIO 0x481aa000 (irq = 160, base_baud = 3000000) is a 8250
[ 0.353934] [drm] Initialized drm 1.1.0 20060810
[ 0.354607] usbcore: registered new interface driver udl
[ 0.357236] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[ 0.357250] [drm] No driver support for vblank timestamp query.
[ 0.371907] Console: switching to colour frame buffer device 60x50
[ 0.393964] tilcdc 4830e000.lcdc: fb0: frame buffer device
[ 0.404111] [drm] Initialized tilcdc 1.0.0 20121205 on minor 1
[ 0.409864] brd: module loaded
[ 0.450406] loop: module loaded
[ 0.518959] nbd: registered device at major 43
[ 0.533794] rbd: loaded
[ 0.536747] mtdoops: mtd device (mtddev=name/number) must be supplied
[ 0.547606] Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
[ 0.554322] eql: Equalizer2002: Simon Janes (simon@ncm.com) and David S. Miller (davem@redhat.com)
[ 0.556912] tun: Universal TUN/TAP device driver, 1.6
[ 0.556927] tun: (C) 1999-2004 Max Krasnyansky <maxk@qualcomm.com>
[ 0.608083] davinci_mdio 4a101000.mdio: davinci mdio revision 1.6
[ 0.608102] davinci_mdio 4a101000.mdio: detected phy mask fffffffe
[ 0.610363] libphy: 4a101000.mdio: probed
[ 0.610390] davinci_mdio 4a101000.mdio: phy[0]: device 4a101000.mdio:00, driver Marvell 88E1510
[ 0.611148] cpsw 4a100000.ethernet: Detected MACID = 70:b3:d5:ac:10:4f
[ 0.612787] PPP generic driver version 2.4.2
[ 0.613119] PPP BSD Compression module registered
[ 0.613135] PPP Deflate Compression module registered
[ 0.613164] PPP MPPE Compression module registered
[ 0.613183] NET: Registered protocol family 24
[ 0.614806] aoe: AoE v85 initialised.
[ 0.615625] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[ 0.615673] ehci-platform: EHCI generic platform driver
[ 0.615871] ehci-omap: OMAP-EHCI Host Controller driver
[ 0.616630] usbcore: registered new interface driver usb-storage
[ 0.617151] mousedev: PS/2 mouse device common for all mice
[ 0.618236] TI-am335x-tsc TI-am335x-tsc: ti,charge-delay not specified
[ 0.618771] input: ti-tsc as /devices/platform/ocp/44e0d000.tscadc/TI-am335x-tsc/input/input0
[ 0.620600] i2c /dev entries driver
[ 0.622290] input: tps65217_pwr_but as /devices/platform/ocp/44e0b000.i2c/i2c-0/0-0024/input/input1
[ 0.646687] tps65217 0-0024: TPS65217 ID 0xe version 1.2
[ 0.647205] at24 0-0050: 32768 byte 24c256 EEPROM, writable, 1 bytes/write
[ 0.648549] rtc-pcf8523 0-0068: rtc core: registered rtc-pcf8523 as rtc0
[ 0.648777] omap_i2c 44e0b000.i2c: bus 0 rev0.11 at 400 kHz
[ 0.649761] omap_i2c 4802a000.i2c: bus 1 rev0.11 at 400 kHz
[ 0.657728] omap_wdt: OMAP Watchdog Timer Rev 0x01: initial timeout 60 sec
[ 0.657889] Bluetooth: HCI UART driver ver 2.3
[ 0.657901] Bluetooth: HCI UART protocol H4 registered
[ 0.657908] Bluetooth: HCI UART protocol BCSP registered
[ 0.657915] Bluetooth: HCI UART protocol LL registered
[ 0.657922] Bluetooth: HCI UART protocol ATH3K registered
[ 0.657929] Bluetooth: HCI UART protocol Three-wire (H5) registered
[ 0.658052] Bluetooth: HCI UART protocol BCM registered
[ 0.658060] Bluetooth: HCI UART protocol QCA registered
[ 0.658167] usbcore: registered new interface driver btusb
[ 0.658183] Bluetooth: Generic Bluetooth SDIO driver ver 0.1
[ 0.658484] cpuidle: enable-method property 'ti,am3352' found operations
[ 0.659014] pinctrl-single 44e10800.pinmux: pin 44e10960.0 already requested by 48030000.spi; cannot claim for 48060000.mmc
[ 0.670282] pinctrl-single 44e10800.pinmux: pin-88 (48060000.mmc) status -22
[ 0.677372] pinctrl-single 44e10800.pinmux: could not request pin 88 (44e10960.0) from group pinmux_mmc1_pins on device pinctrl-single
[ 0.689602] omap_hsmmc 48060000.mmc: Error applying setting, reverse things back
[ 0.697212] omap_hsmmc 48060000.mmc: Got CD GPIO
[ 0.761972] hidraw: raw HID events driver (C) Jiri Kosina
[ 0.762621] usbcore: registered new interface driver usbhid
[ 0.762633] usbhid: USB HID core driver
[ 0.762916] ashmem: initialized
[ 0.763496] remoteproc0: wkup_m3 is available
[ 0.763508] remoteproc0: Note: remoteproc is still under development and considered experimental.
[ 0.763516] remoteproc0: THE BINARY FORMAT IS NOT YET FINALIZED, and backward compatibility isn't yet guaranteed.
[ 0.775946] NET: Registered protocol family 10
[ 0.784008] mip6: Mobile IPv6
[ 0.784114] NET: Registered protocol family 17
[ 0.784340] Bluetooth: RFCOMM TTY layer initialized
[ 0.784363] Bluetooth: RFCOMM socket layer initialized
[ 0.784400] Bluetooth: RFCOMM ver 1.11
[ 0.784424] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[ 0.784431] Bluetooth: BNEP filters: protocol multicast
[ 0.784454] Bluetooth: BNEP socket layer initialized
[ 0.784465] Bluetooth: HIDP (Human Interface Emulation) ver 1.2
[ 0.784479] Bluetooth: HIDP socket layer initialized
[ 0.784603] Key type dns_resolver registered
[ 0.784631] Key type ceph registered
[ 0.789158] libceph: loaded (mon/osd proto 15/24)
[ 0.789180] mpls_gso: MPLS GSO support
[ 0.789479] omap_voltage_late_init: Voltage driver support not added
[ 0.798672] PM: Cannot get wkup_m3_ipc handle
[ 0.803209] ThumbEE CPU extension supported.
[ 0.803244] Registering SWP/SWPB emulation handler
[ 0.804385] registered taskstats version 1
[ 0.804515] zswap: loaded using pool lzo/zbud
[ 0.806233] Key type encrypted registered
[ 0.812447] PM: bootloader does not support rtc-only!
[ 0.813305] remoteproc0: powering up wkup_m3
[ 0.813329] remoteproc0: Booting fw image am335x-pm-firmware.elf, size 219735
[ 0.813589] remoteproc0: remote processor wkup_m3 is now up
[ 0.813651] wkup_m3_ipc 44e11324.wkup_m3_ipc: CM3 Firmware Version = 0x191
[ 0.814393] input: user_keys as /devices/platform/user_keys/input/input2
[ 0.815635] rtc-pcf8523 0-0068: setting system clock to 2020-07-11 05:00:37 UTC (1594443637)
[ 0.815678] of_cfs_init
[ 0.815739] of_cfs_init: OK
[ 0.822445] PM: Hibernation image not present or could not be loaded.
[ 0.823031] mmc1: MAN_BKOPS_EN bit is not set
[ 0.824413] Waiting for root device /dev/mmcblk1p2...
[ 0.831058] mmc1: new high speed MMC card at address 0001
[ 0.836641] mmcblk1: mmc1:0001 DG4008 7.28 GiB
[ 0.841304] mmcblk1boot0: mmc1:0001 DG4008 partition 1 4.00 MiB
[ 0.846114] mmcblk1boot1: mmc1:0001 DG4008 partition 2 4.00 MiB
[ 0.847520] mmcblk1: p1 p2 p3 p4
[ 1.159609] EXT4-fs (mmcblk1p2): recovery complete
[ 1.160189] EXT4-fs (mmcblk1p2): mounted filesystem with ordered data mode. Opts: (null)
[ 1.160260] VFS: Mounted root (ext4 filesystem) on device 179:2.
[ 1.164510] devtmpfs: mounted
[ 1.164913] Freeing unused kernel memory: 316K (c0a19000 - c0a68000)
[ 1.366410] random: systemd urandom read with 26 bits of entropy available
[ 1.696671] systemd[1]: Configuration file /lib/systemd/system/Sheepapp.service is marked executable. Please remove executable permission bits. Proceeding anyway.
[ 1.770250] systemd[1]: Cannot add dependency job for unit display-manager.service, ignoring: Unit display-manager.service failed to load: No such file or directory.
[ 1.770531] systemd[1]: Found ordering cycle on basic.target/start
[ 1.770555] systemd[1]: Found dependency on sysinit.target/start
[ 1.770578] systemd[1]: Found dependency on systemd-update-utmp.service/verify-active
[ 1.770597] systemd[1]: Found dependency on basic.target/start
[ 1.770616] systemd[1]: Breaking ordering cycle by deleting job systemd-update-utmp.service/verify-active
[ 1.770635] systemd[1]: Job systemd-update-utmp.service/verify-active deleted to break ordering cycle starting with basic.target/start
[ 1.783320] systemd[1]: Found ordering cycle on basic.target/start
[ 1.783347] systemd[1]: Found dependency on sysinit.target/start
[ 1.783369] systemd[1]: Found dependency on systemd-tmpfiles-setup-dev.service/start
[ 1.783388] systemd[1]: Found dependency on basic.target/start
[ 1.783407] systemd[1]: Breaking ordering cycle by deleting job systemd-tmpfiles-setup-dev.service/start
[ 1.783425] systemd[1]: Job systemd-tmpfiles-setup-dev.service/start deleted to break ordering cycle starting with basic.target/start
[ 1.795594] systemd[1]: Found ordering cycle on basic.target/start
[ 1.795617] systemd[1]: Found dependency on sysinit.target/start
[ 1.795638] systemd[1]: Found dependency on systemd-journald.service/start
[ 1.795657] systemd[1]: Found dependency on Sheepapp.service/start
[ 1.795673] systemd[1]: Found dependency on basic.target/start
[ 1.795690] systemd[1]: Breaking ordering cycle by deleting job systemd-journald.service/start
[ 1.795709] systemd[1]: Job systemd-journald.service/start deleted to break ordering cycle starting with basic.target/start
[ 1.937935] systemd-udevd[169]: starting version 215
[ 2.058270] EXT4-fs (mmcblk1p2): re-mounted. Opts: errors=remount-ro
[ 2.127552] systemd[1]: Found ordering cycle on systemd-journald.service/start
[ 2.127595] systemd[1]: Found dependency on Sheepapp.service/start
[ 2.127618] systemd[1]: Found dependency on basic.target/start
[ 2.127637] systemd[1]: Found dependency on sysinit.target/start
[ 2.127655] systemd[1]: Found dependency on systemd-journald.service/start
[ 2.127673] systemd[1]: Unable to break cycle
[ 2.146209] systemd[1]: Requested transaction contains an unfixable cyclic ordering dependency: Transaction order is cyclic. See system logs for details.
[ 2.146280] systemd[1]: systemd-journald.socket failed to queue service startup job (Maybe the service file is missing or not a non-template unit?): Transaction order is cyclic. See system logs for d.
[ 2.146631] systemd[1]: Unit systemd-journald.socket entered failed state.
[ 3.250733] 47401300.usb-phy supply vcc not found, using dummy regulator
[ 3.265076] 47401b00.usb-phy supply vcc not found, using dummy regulator
[ 3.409115] omap_rng 48310000.rng: OMAP Random Number Generator ver. 20
[ 3.759452] omap-aes 53500000.aes: OMAP AES hw accel rev: 3.2
[ 3.794250] omap-sham 53100000.sham: hw accel on OMAP rev 4.3
[ 3.814816] FAT-fs (mmcblk1p1): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.
[ 4.138771] systemd[1]: Found ordering cycle on systemd-journald.service/start
[ 4.138814] systemd[1]: Found dependency on Sheepapp.service/start
[ 4.138835] systemd[1]: Found dependency on basic.target/start
[ 4.138855] systemd[1]: Found dependency on sysinit.target/start
[ 4.138874] systemd[1]: Found dependency on systemd-journald.service/start
[ 4.138892] systemd[1]: Unable to break cycle
[ 4.145467] systemd[1]: Requested transaction contains an unfixable cyclic ordering dependency: Transaction order is cyclic. See system logs for details.
[ 4.145536] systemd[1]: systemd-journald-dev-log.socket failed to queue service startup job (Maybe the service file is missing or not a non-template unit?): Transaction order is cyclic. See system lo.
[ 4.145716] systemd[1]: Unit systemd-journald-dev-log.socket entered failed state.
[ 4.807371] musb-hdrc: ConfigData=0xde (UTMI-8, dyn FIFOs, bulk combine, bulk split, HB-ISO Rx, HB-ISO Tx, SoftConn)
[ 4.807395] musb-hdrc: MHDRC RTL version 2.0
[ 4.807404] musb-hdrc: setup fifo_mode 4
[ 4.807422] musb-hdrc: 28/31 max ep, 16384/16384 memory
[ 4.821829] musb-hdrc: ConfigData=0xde (UTMI-8, dyn FIFOs, bulk combine, bulk split, HB-ISO Rx, HB-ISO Tx, SoftConn)
[ 4.821851] musb-hdrc: MHDRC RTL version 2.0
[ 4.821860] musb-hdrc: setup fifo_mode 4
[ 4.821874] musb-hdrc: 28/31 max ep, 16384/16384 memory
[ 4.825460] musb-hdrc musb-hdrc.1.auto: MUSB HDRC host driver
[ 4.825504] musb-hdrc musb-hdrc.1.auto: new USB bus registered, assigned bus number 1
[ 4.828480] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002
[ 4.828502] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[ 4.828512] usb usb1: Product: MUSB HDRC host driver
[ 4.828521] usb usb1: Manufacturer: Linux 4.4.16 musb-hcd
[ 4.828530] usb usb1: SerialNumber: musb-hdrc.1.auto
[ 4.832531] hub 1-0:1.0: USB hub found
[ 4.832621] hub 1-0:1.0: 1 port detected
[ 5.220327] usb 1-1: new full-speed USB device number 2 using musb-hdrc
[ 5.273232] net eth0: initializing cpsw version 1.12 (0)
[ 5.273255] net eth0: initialized cpsw ale version 1.4
[ 5.273264] net eth0: ALE Table size 1024
[ 5.276187] net eth0: phy found : id is : 0x1410dd1
[ 5.285327] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[ 5.379690] usb 1-1: New USB device found, idVendor=10c4, idProduct=ea60
[ 5.379714] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 5.379724] usb 1-1: Product: CP2102 USB to UART Bridge Controller
[ 5.379734] usb 1-1: Manufacturer: Silicon Labs
[ 5.379743] usb 1-1: SerialNumber: 0001
[ 5.523791] usbcore: registered new interface driver usbserial
[ 5.537093] usbcore: registered new interface driver usbserial_generic
[ 5.557186] usbserial: USB Serial support registered for generic
[ 5.592264] usbcore: registered new interface driver cp210x
[ 5.604265] usbserial: USB Serial support registered for cp210x
[ 5.604443] cp210x 1-1:1.0: cp210x converter detected
[ 5.607466] usb 1-1: cp210x converter now attached to ttyUSB0
[ 6.203786] systemd-logind[344]: New seat seat0.
[ 6.245462] systemd-logind[344]: Watching system buttons on /dev/input/event1 (tps65217_pwr_but)
[ 7.006953] random: nonblocking pool is initialized
[ 7.086270] EXT4-fs (mmcblk1p4): 1 truncate cleaned up
[ 7.086295] EXT4-fs (mmcblk1p4): recovery complete
[ 7.090937] EXT4-fs (mmcblk1p4): mounted filesystem with ordered data mode. Opts: (null)
[ 7.720936] using random self ethernet address
[ 7.720963] using random host ethernet address
[ 7.742781] using random self ethernet address
[ 7.742808] using random host ethernet address
[ 7.758850] usb0: HOST MAC 70:b3:d5:ac:10:52
[ 7.759434] usb0: MAC 70:b3:d5:ac:10:50
[ 7.764019] usb1: HOST MAC 70:b3:d5:ac:10:53
[ 7.768399] usb1: MAC 70:b3:d5:ac:10:51
[ 10.849087] bridge: automatic filtering via arp/ip/ip6tables has been deprecated. Update your scripts to load br_netfilter if you need this.
[ 10.865462] device usb0 entered promiscuous mode
[ 10.877359] device usb1 entered promiscuous mode
[ 10.894547] IPv6: ADDRCONF(NETDEV_UP): usb0: link is not ready
[ 10.905536] IPv6: ADDRCONF(NETDEV_UP): usb1: link is not ready
[ 10.918051] IPv6: ADDRCONF(NETDEV_UP): br0: link is not ready
root@arm:~#
CTRL-A Z for help | 115200 8N1 | NOR | Minicom 2.7 | VT102 | Offline | ttyUSB0
hiten chauhan1 Answer
As you can see in the dmesg output:
[ 5.379690] usb 1-1: New USB device found, idVendor=10c4, idProduct=ea60
Looking that up, e.g. here: https://www.google.com/search?q=usb%20vendor%20id%2010c4
Tells you that it's a "Silicon Labs" USB device, who also make the CP2102.
The log does not identify other devices (ignore the linux kernel root hub). So either you have also a CP2102 attached (and the FTDI is not properly connected) or the device you think is a FTDI based device, is not.
In addition you can identify currently enumerated devices using the lsusb command.
The automatic loading is usually done by udev or a similar user space daemon/mechanism. A decent explanation can be found e.g. here: https://lwn.net/Articles/740455/
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