No debug output after kernel upgrade

[laurentcoignot]

Dear contributors,

we are using a custom board with iMX6DL running on it.

We were running 3.0.35 kernel and have decided to move to 3.14.56 due to support of ath10k module.

The u-boot used is 2014.04-rc1 customized for our board.

We made the dts file which is very basic for now, only including the debug UART on ttymxc1 (uart2)

When loading the kernel, I can't get debug outptu, although everything seems (to me at least) properly configured.

Here is the boot output

U-Boot 2014.01-rc3-CP (Nov 25 2015 - 10:56:53)

CPU:   Freescale i.MX6DL rev1.1 at 792 MHz

Reset cause: POR

I2C:   ready

DRAM:  1 GiB

PMIC: device ID = 10, silicon rev = 11, FABID = 00

NAND:  4096 MiB

MMC:   FSL_SDHC: 0, FSL_SDHC: 1, FSL_SDHC: 2

SF: Detected AT25DF641 with page size 256 Bytes, erase size 4 KiB, total 8 MiB

In:    serial

Out:   serial

Err:   serial

USB charger configuration

00000000 00 F0 DC 78 45 12 00 18

Vendor ID (expected 0x4X): 45

USB current limit set to 1500mA.

Charge voltage set to 4.2V.

Charge current set to 700mA.

ADC configuration

ADC value = 4032 mV

Over range alert : 0 - Under range alert : 0

FPGA loading

SF: Detected AT25DF641 with page size 256 Bytes, erase size 4 KiB, total 8 MiB

Loading FPGA Device 0...

Done.

SF: Detected AT25DF641 with page size 256 Bytes, erase size 4 KiB, total 8 MiB

Node is docked to the Docking station.

USB HUB configuration...

USB HUB configured.

USB attached.

ITM CPU EEPROM data OK

Mac Address 00:09:99:00:1c:a4

Net:   using phy at 7

FEC [PRIME]

Enter password - autoboot in 2 seconds

U-Boot >> tftp 0x18000000 imx6dl-cp8825.dtb; tftp 0x12000000 uImage; bootm 0x12000000 - 0x18000000

Using FEC device

TFTP from server 192.168.5.71; our IP address is 192.168.5.212

Filename 'imx6dl-cp8825.dtb'.

Load address: 0x18000000

Loading: T ######

         4.9 KiB/s

done

Bytes transferred = 30572 (776c hex)

Using FEC device

TFTP from server 192.168.5.71; our IP address is 192.168.5.212

Filename 'uImage'.

Load address: 0x12000000

Loading: #################################################################

         #################################################################

         #################################################################

         #################################################################

         #################################################################

         #################################################################

         #################################################################

         #################################################################

         #################################################################

         #################################################################

         #################################################################

         #################################################################

         #####################

         156.3 KiB/s

done

Bytes transferred = 4096168 (3e80a8 hex)

## Booting kernel from Legacy Image at 12000000 ...

   Image Name:   Linux-3.14.56-cp-rc01

   Created:      2015-11-25  17:17:03 UTC

   Image Type:   ARM Linux Kernel Image (uncompressed)

   Data Size:    4096104 Bytes = 3.9 MiB

   Load Address: 10000000

   Entry Point:  10000000

   Verifying Checksum ... OK

## Flattened Device Tree blob at 18000000

   Booting using the fdt blob at 0x18000000

   Loading Kernel Image ... OK

   Loading Device Tree to 47ff5000, end 47fff76b ... OK

Starting kernel ...

Uncompressing Linux... done, booting the kernel.

Here are my dts and dtsi files:

imx6dl-cp8825.dts :

/dts-v1/;  #include "imx6dl.dtsi" #include "imx6qdl-cp8825.dtsi"  / {     model = "CP8825 i.MX6 Dual Lite Board";     compatible = "fsl,imx6dl"; }; }; 

imx6dl-cp88525.dtsi:

/ {     memory {         reg = <0x10000000 0x40000000>;     }; };  &uart2 {     pinctrl-names = "default";     pinctrl-0 = <&pinctrl_uart2_1>;     status = "okay"; }; 

my kernel config has been modified to use uart2 for early debug : (see .config file for further details on kernel config)

CONFIG_DEBUG_LL=y

CONFIG_DEBUG_IMX6Q_UART=y

CONFIG_DEBUG_IMX_UART_PORT=2

CONFIG_EARLY_PRINTK=y

my default kernel command string is as is : noinitrd console=ttymxc1,115200n8

and the u-boot bootargs is :

bootargs=console=ttymxc1,115200 nfsrootdebug root=/dev/nfs rw nfsroot=192.168.5.71:/tftpboot/rootfs,nolock ip=192.168.5.212:192.168.5.71::::eth0:off

We use Linaro GCC 4.9.2 (gcc version 4.9.2 20140904 (prerelease) (crosstool-NG linaro-1.13.1-4.9-2014.09 - Linaro GCC 4.9-2014.09) )

I can't figure why I can get no output on serial tty

Any hint of what I am doing wrong please ?

Thanks in advance

Regards

Laurent

Original Attachment has been moved to: 1.config.zip

[alejandrolozan1]

Hi,

Please make sure you have the serial1 = &uart2 in the aliases node and the correct pin configuration.

Can you share the <&pinctrl_uart2_1> description?

Best Regards,

Alejandro

[laurentcoignot]

Hi Alejandro,

Thank you for your answer.

I did an include of imx6qdl.dtsi so the pinout and serial assignation are the standard one in kernel 3.14.56. So yes, serial1 = uart2 id included and the pinout is as below :

			uart2 {
				pinctrl_uart2_1: uart2grp-1 {
					fsl,pins = <
						MX6QDL_PAD_EIM_D26__UART2_TX_DATA 0x1b0b1
						MX6QDL_PAD_EIM_D27__UART2_RX_DATA 0x1b0b1
					>;
				};

};

In addition, I made further tests and using the same dts file on my Sabre SD card (changing bootargs and Low Level UART to match ttymxc0 on SabreSD of course)

I found a difference (I don't know if it makes sense) between the two starts of boards :

• On my custom board, I can see this while kernel is loading :

   Loading Device Tree to 47ff5000, end 47fffd72 ... OK

• On the Sabre SD, this is the following output

   Using Device Tree in place at 18000000, end 1800ad72

As we are using a U-Boot, designed to boot our old 3.0.35 kernel, I don't know if I have to modify some U-Boot settings or args to pass to the kernel at boot to use the DTS file "in place".

[alejandrolozan1]

Hi,

You have to append the dtb to your zImage so old verions of Uboot see the image as a normal zImage.

Please try that. You can find more information about this at http://free-electrons.com/pub/conferences/2013/elce/petazzoni-device-tree-dummies/petazzoni-device-t...

slide number 8.

Best Regards,

Alejandro