No kernel debug output via serial ttyUSB0


I bought a bubblegum-96 board from taobao ( No UART debug board was provided…So I used UART USB convert to connect PIN 1(GND), PIN 11 and PIN 13.
I use SD-Card upgrade method to install debian image, and could got the debug output message of firmware and u-boot for each reboot. But I could NOT get any kernel output like “Starting Kernel…” via serial (BTW: I could see kernel message output in the HDMI screen tty0). Do I need connect more PIN beside PIN 1,11,13?
Please see my output via serial in below:

[SECM] ver 1.0-b3cf629 (build Mar 7 2016 15:27:38)
[SECM] first boot: 0
atc260x_early_init bus_num:3, bus_mfp:0
owl_i2c_init bus_num:3, bus_mfp:0,IO_voltage:0
PMU:found PMIC type 2 ver 3
PMU:dat = 0x5a78!!!
PMU:RTC acc closed!!!
PMU:PMU_SYS_CTL0 0xe055, CTL1 0x57, CTL2 0x680, CTL3 0x4000
core_freq = 1104 dev_freq = 660 display_freq = 1056
owl_pm_get_s2_flag: get S2 flag 0
[SECM] ddr_init(mode:1)
clock_get = 552 mz
[DDR] ddr_clk 0x228
[DDR] ddr_type 0x2
[DDR] ddr_single_cap 0x5
[DDR] ddr_width 0x0
[DDR] rank 0x2
[DDR] dual_chan 0x2
[DDR] clk_drv 0x99
[DDR] ca_drv 0xdd
[DDR] dram_odt_en 0x0
[DDR] twls_adj 0x0
[DDR] pad_tsel 0x3ddf77dd
cs map value 3 !
DDR PHY PLL not lock!
DDR PHY PLL locked!
cs map value 3 !
DDR PHY PLL not lock!
DDR PHY PLL locked!
channel 0 init_start processing!
channel 0 init_start pass!
channel 1 init_start processing!
channel 1 init_start pass!
[DDR normal] init clk 552 Mhz
[SECM] load bl31
[SECM] load bl32
[SECM] load uboot
[SECM] load app
[SECM] secmbrc consume 322 ms
[SECM] jump to boot app
in fourth ,bootdev = 0x22
dvfs find
NOTICE: BL3-1: v1.0(debug):0857b9e
NOTICE: BL3-1: Built : 15:27:42, Mar 7 2016
INFO: owl: setup security space(1f000000~1fa00000)
NOTICE: atc260x_early_reinit
INFO: BL3-1: Initializing runtime services
INFO: BL3-1: Initializing BL3-2
NOTICE: TSP: v1.0(debug):0857b9e
NOTICE: TSP: Built : 15:27:43, Mar 7 2016
INFO: TSP: Total memory base : 0x1f202000
INFO: TSP: Total memory size : 0x7000 bytes
INFO: TSP: cpu 0x80000000: 1 smcs, 1 erets 1 cpu on requests
INFO: BL3-1: Preparing for EL3 exit to normal world
INFO: BL3-1: Next image address = 0x11000000
INFO: BL3-1: Next image spsr = 0x3c9

U-Boot 2015.07-00027-g76263ba (Apr 20 2016 - 16:14:44 +0800)S900 96BOARD

Relocation Offset is: 6ef46000
Relocating to 7ff46000, new gd at 7df43e08, sp at 7df41cb0
PMU_INFO:found PMIC type 2 ver 3
PMU_INFO:PMU_SYS_CTL0 0xe0d5, CTL1 0x57, CTL2 0x680, CTL3 0x4000
owl_init_power_status: power_status: 0
clk: core_pll 1104MHz, dev_pll 660MHz, display_pll 1056MHz
MMC: MMC: source clk CMU_DEVPLL:660000000Hz
error: SDC0 send CMD8, No rsp
error: SDC0 send CMD55, No rsp
error: SDC0 send CMD1, No rsp
Card did not respond to voltage select!
host0 scan err
host0 checkout to uartpin
MMC: sourc


This log looks pretty much the same are your u-boot log… does that mean your changes to u-boot has fixed this issue too?


Hi danielt,
just like my reply in another post, the serial console only print u-boot message like above, and will stop to output anything including kernel message log after “MMC: sourc”…