Re: [beagleboard] BBB Clone change UART0 to UART4

[Charles Steinkuehler]

On 1/29/2019 12:50 AM, Dave wrote:
> The snippet below is in the common dtsi for all am335x boards. 
> 
> What I am asking is if that snippet is meaningless, or if it has the actual 
> effect of switching standard out at some point to uart0 ?
> 
> Also what is the simplest way to rebuild the am335x-bone-uboot-univ.dtb ?
> I am not familiar with compiling dtb's in the linux kernel tree. 
> Those have an assortment of includes. 
> I am used to compiling standalone dts/dtb's 
> 
> Is there a 
> 
> make dtb
> 
> that will build the dtb for the current .config device ?

It's "make dtbs", or you can specify the specific dtb you want to build:

https://www.lynxbee.com/how-to-compile-dts-to-dtb-from-linux-kernel-and-manually/

> chosen {
> stdout-path = 
> };

That could be causing your problems, and it almost certainly wouldn't
hurt to change it:

https://www.kernel.org/doc/Documentation/devicetree/bindings/chosen.txt

-- 
Charles Steinkuehler
char...@steinkuehler.net

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Re: [beagleboard] BBB Clone change UART0 to UART4

[Charles Steinkuehler]

On 1/29/2019 12:58 AM, Dave wrote:
> I am trapping serial output on BOTH the target board and a BBB booting the 
> SAME SD card, with the only difference being the setting of init_console. 
> After each has run as far as it will - in the case of the BBB I get a login 
> prompt. 

I don't think this is an "apples to apples" test.  I haven't crawled
into the low-level differences between the BBB and the Octavo SIP, but
I _think_ at least the DRAM settings are different.  Do you have a
Pocket Beagle or one of the other Octavo boards handy for testing?

Are you sure U-Boot is patched to handle your EEPROM-less board?

That said, if you were having SDRAM timing issues I'd expect the
kernel to crash and I wouldn't expect the failure to be so consistent
with USR LEDs still blinking.  So I wouldn't chase SDRAM issues right
away, but just keep in mind that might be part of your problems.

> I vimdiff the serial output captures. 
> 
> On the BBB I get alot of console output from the end of all the eqep driver 
> setup through the login prompt. 
> On the target all serial output stops with the eqep output - but the LEDS 
> continue to be active. 
> As they are soft - something is still executing

See if adding a getty for UART4 gets you a login prompt.  You don't
really need the kernel console if you can login, and with the USR LEDs
blinking it sounds like the system is probably still running.

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Re: [beagleboard] BBB Clone change UART0 to UART4

[Dave]

I am trying to avoid using toggling GPIO's to trace.  I know how to do it.  
But that could take weeks to find the problem. 

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Re: [beagleboard] BBB Clone change UART0 to UART4

[Dave]

I KNOW this is a problem that I can ultimately defeat. 

I know I can attach a JTAG or I can add code to LINUX to flash LED's or 
something like that to place sentinels and divide and conquer until I find 
the offending problem. 

But that could be a very long tedious process possibily taking weeks. 

It is my beleif that this board is pretty close to working. 

I am looking for ideas to avoid the long and tedious approach I am already 
well aware of. 

I have done Linux board bringup on a completely new board - one that there 
were no existing reference boards for.
I am trying to avoid having to get that deep into things and hoping that 
the knowledge in this group can help shortcut the process. 

And I appreciate the help. 


 





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Re: [beagleboard] BBB Clone change UART0 to UART4

[Dave]

>
> I am booting my "custom" SD card in a BBB for reference purposes. 


My "process" is start u-boot, use editenv to chang the console as 
appropriate for the current board - ttyO0 on the bbb and ttyO4 on the 
target. 
saveenv. 

reset the board with serial capture turned on .

Do the above with both the BBB and the target board. 

Then vimdiff the captures looking for meaningfull differences. 

So I know the SD card is good.  And that aside from the console it works on 
a BBB.  






 

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Re: [beagleboard] BBB Clone change UART0 to UART4

[Dave]

Serial capture files attached. 

I used vim to change the timestamps to  to allow ignoring timestamp 
differences when comparing the files. 

mts.txt is the boot on the target board.
bbb.txt is the boot on a BBB

If you diff the two files there are very very few differences - none of 
which are consequential, prior to completing loading the eqep driver. 
After than the target board goes silent - though the leds flash. 
and the bbb continues and eventually shows a login prompt. 

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picocom v3.1

port is: /dev/ttyUSB0
flowcontrol: none
baudrate is: 115200
parity is  : none
databits are   : 8
stopbits are   : 1
escape is  : C-a
local echo is  : no
noinit is  : no
noreset is : no
hangup is  : no
nolock is  : no
send_cmd is: sz -vv
receive_cmd is : rz -vv -E
imap is: 
omap is: 
emap is: crcrlf,delbs,
logfile is : none
initstring : none
exit_after is  : not set
exit is: no

Type [C-a] [C-h] to see available commands
Terminal ready
U-Boot SPL 2018.09-2-g58a2108e52 (Jan 06 2019 - 10:12:41 -0600)
Trying to boot from MMC2
Loading Environment from EXT4... OK


U-Boot 2018.09-2-g58a2108e52 (Jan 06 2019 - 10:12:41 -0600), Build: 
jenkins-github_Bootloader-Builder-95

CPU  : AM335X-GP rev 2.1
I2C:   ready
DRAM:  512 MiB
No match for driver 'omap_hsmmc'
No match for driver 'omap_hsmmc'
Some drivers were not found
Reset Source: Power-on reset has occurred.
RTC 32KCLK Source: External.
MMC:   OMAP SD/MMC: 0, OMAP SD/MMC: 1
Loading Environment from EXT4... OK
Board: BeagleBone Black
BeagleBone Black:
BeagleBone: cape eeprom: i2c_probe: 0x54:
BeagleBone: cape eeprom: i2c_probe: 0x55:
BeagleBone: cape eeprom: i2c_probe: 0x56:
BeagleBone: cape eeprom: i2c_probe: 0x57:
Net:   eth0: MII MODE
cpsw, usb_ether
Press SPACE to abort autoboot in 2 seconds
board_name=[A335BNLT] ...
board_rev=[00C0] ...
switch to partitions #0, OK
mmc0 is current device
SD/MMC found on device 0
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
gpio: pin 56 (gpio 56) value is 0
gpio: pin 55 (gpio 55) value is 0
gpio: pin 54 (gpio 54) value is 0
gpio: pin 53 (gpio 53) value is 1
switch to partitions #0, OK
mmc0 is current device
gpio: pin 54 (gpio 54) value is 1
Checking for: /uEnv.txt ...
Checking for: /boot.scr ...
Checking for: /boot/boot.scr ...
Checking for: /boot/uEnv.txt ...
gpio: pin 55 (gpio 55) value is 1
2134 bytes read in 58 ms (35.2 KiB/s)
Loaded environment from /boot/uEnv.txt
Checking if uname_r is set in /boot/uEnv.txt...
gpio: pin 56 (gpio 56) value is 1
Running uname_boot ...
loading /boot/vmlinuz-4.18.20-bone16 ...
6582784 bytes read in 508 ms (12.4 MiB/s)
debug: [enable_uboot_overlays=1] ...
debug: [enable_uboot_cape_universal=1] ...
debug: [uboot_base_dtb_univ=am335x-boneblack-uboot-univ.dtb] ...
uboot_overlays: [uboot_base_dtb=am335x-boneblack-uboot-univ.dtb] ...
uboot_overlays: Switching too: dtb=am335x-boneblack-uboot-univ.dtb ...
loading /boot/dtbs/4.18.20-bone16/am335x-boneblack-uboot-univ.dtb ...
158293 bytes read in 94 ms (1.6 MiB/s)
uboot_overlays: [fdt_buffer=0x6] ...
uboot_overlays: uboot loading of [/lib/firmware/BB-BONE-eMMC1-01-00A0.dtbo] 
disabled by /boot/uEnv.txt [disable_uboot_overlay_emmc=1]...
uboot_overlays: uboot loading of [/lib/firmware/BB-HDMI-TDA998x-00A0.dtbo] 
disabled by /boot/uEnv.txt [disable_uboot_overlay_video=1]...
uboot_overlays: uboot loading of [/lib/firmware/BB-ADC-00A0.dtbo] disabled by 
/boot/uEnv.txt [disable_uboot_overlay_adc=1]...
uboot_overlays: loading /lib/firmware/AM335X-PRU-RPROC-4-14-TI-00A0.dtbo ...
3513 bytes read in 184 ms (18.6 KiB/s)
loading /boot/initrd.img-4.18.20-bone16 ...
4748142 bytes read in 398 ms (11.4 MiB/s)
debug: [console=ttyO0,115200n8 bone_capemgr.uboot_capemgr_enabled=1 
root=/dev/mmcblk0p1 ro rootfstype=ext4 rootwait coherent_pool=1M net.ifnames=0] 
...
debug: [bootz 0x8200 0x8808:48736e 8800] ...
## Flattened Device Tree blob at 8800
   Booting using the fdt blob at 0x8800
   Loading Ramdisk to 8fb78000, end 836e ... OK
   reserving fdt memory region: addr=8800 size=88000
   Loading Device Tree to 8faed000, end 8fb77fff ... OK

Starting kernel ...

 Booting Linux on physical CPU 0x0
 Linux version 4.18.20-bone16 (root@z370-dhlii) (gcc version 7.3.1 20180425 
[linaro-7.3-2018.05 revision d29120a424ecfbc167ef90065c0eeb7f91977701] (Linaro 
GCC 7.3-2018.05)) #1xross PREEMPT Fri Jan 25 15:45:42 EST 2019
 CPU: ARMv7 Processor 

Re: [beagleboard] BBB Clone change UART0 to UART4

[Dave]

I am trapping serial output on BOTH the target board and a BBB booting the 
SAME SD card, with the only difference being the setting of init_console. 
After each has run as far as it will - in the case of the BBB I get a login 
prompt. 
I vimdiff the serial output captures. 

On the BBB I get alot of console output from the end of all the eqep driver 
setup through the login prompt. 
On the target all serial output stops with the eqep output - but the LEDS 
continue to be active. 
As they are soft - something is still executing



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Re: [beagleboard] BBB Clone change UART0 to UART4

[Dave]

I have made no changes to the root filesystem EXCEPT using 
bb-kernel/build_deb.sh  to build a relatively stripped kernel and 
installing that when the immage is booted on a BBB before switching to the 
target board.  

I have not messed with init, inittab, or systemd or getty. 
That may be something I look at next. 

I know UART4 is working.  If I setup /init /etc/inittab to run getty on it 
MAYBE I can get a login prompt - if linux boots far enough to spawn init. 

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Re: [beagleboard] BBB Clone change UART0 to UART4

[Dave]

The snippet below is in the common dtsi for all am335x boards. 

What I am asking is if that snippet is meaningless, or if it has the actual 
effect of switching standard out at some point to uart0 ?

Also what is the simplest way to rebuild the am335x-bone-uboot-univ.dtb ?
I am not familiar with compiling dtb's in the linux kernel tree. 
Those have an assortment of includes. 
I am used to compiling standalone dts/dtb's 

Is there a 

make dtb

that will build the dtb for the current .config device ?





chosen {
stdout-path = 
};

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Re: [beagleboard] BBB Clone change UART0 to UART4

['Mark Lazarewicz' via BeagleBoard]

..and then there's always the JTAG cable!  :)

Another option Dave There was a guy in here who consistently talks about 
toggling GPIOs and LESs. I'D ask him where to place these to shed light on 
what's going

Sent from Yahoo Mail on Android 
 
  On Mon, Jan 28, 2019 at 4:10 PM, Charles 
Steinkuehler wrote:   On 1/28/2019 12:33 PM, Dave 
wrote:
> Thank you;
> 
> Changing init_console did the trick. 
> 
> I am now getting console output while booting into linux - For a while. 
> 
> Unfortunately instantly after the Linux eqep Linux Printk's  console IO 
> ceases. 
> 
> It appears the board is still doing something - as the USR0 and USR2 LED's 
> are active, 
> 
> I tried installing a significantly more minimalist kernel in the event that 
> it was stalled dealing with some sub critical hardware. 
> 
> Is it possible that a setting in the Device Tree is re-directing the 
> console ?

The device-tree doesn't affect the kernel console settings AFAIK.

Did you change the getty login console in your root filesystem as well
as the kernel console setting in U-Boot?  You may just be seeing the
end of the kernel output and no login prompt (if you're really lucky).

> Is there an absolute bare minimum BBB Linux configuration that has pretty 
> close to nothing critical except the console enabled ?
> I can add things back in until I figure out what is failing. 

I'm not sure if there's a pre-existing config file floating around,
but you can definitely disable most of the AM335x specific drivers if
you think they're causing problems.

Can you provide the whole serial console boot log?  Other eyes might
spot something wrong.

Also, any chance you can try booting your custom uSD on known good
hardware (eg: some other Octavo based board)?  That might help isolate
what's going wrong.

...and then there's always the JTAG cable!  :)

-- 
Charles Steinkuehler
char...@steinkuehler.net

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Re: [beagleboard] BBB Clone change UART0 to UART4

[Charles Steinkuehler]

On 1/28/2019 12:33 PM, Dave wrote:
> Thank you;
> 
> Changing init_console did the trick. 
> 
> I am now getting console output while booting into linux - For a while. 
> 
> Unfortunately instantly after the Linux eqep Linux Printk's  console IO 
> ceases. 
> 
> It appears the board is still doing something - as the USR0 and USR2 LED's 
> are active, 
> 
> I tried installing a significantly more minimalist kernel in the event that 
> it was stalled dealing with some sub critical hardware. 
> 
> Is it possible that a setting in the Device Tree is re-directing the 
> console ?

The device-tree doesn't affect the kernel console settings AFAIK.

Did you change the getty login console in your root filesystem as well
as the kernel console setting in U-Boot?  You may just be seeing the
end of the kernel output and no login prompt (if you're really lucky).

> Is there an absolute bare minimum BBB Linux configuration that has pretty 
> close to nothing critical except the console enabled ?
> I can add things back in until I figure out what is failing. 

I'm not sure if there's a pre-existing config file floating around,
but you can definitely disable most of the AM335x specific drivers if
you think they're causing problems.

Can you provide the whole serial console boot log?  Other eyes might
spot something wrong.

Also, any chance you can try booting your custom uSD on known good
hardware (eg: some other Octavo based board)?  That might help isolate
what's going wrong.

...and then there's always the JTAG cable!  :)

-- 
Charles Steinkuehler
char...@steinkuehler.net

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Re: [beagleboard] BBB Clone change UART0 to UART4

[Dave]

Thank you;

Changing init_console did the trick. 

I am now getting console output while booting into linux - For a while. 

Unfortunately instantly after the Linux eqep Linux Printk's  console IO 
ceases. 

It appears the board is still doing something - as the USR0 and USR2 LED's 
are active, 

I tried installing a significantly more minimalist kernel in the event that 
it was stalled dealing with some sub critical hardware. 

Is it possible that a setting in the Device Tree is re-directing the 
console ?

Is there an absolute bare minimum BBB Linux configuration that has pretty 
close to nothing critical except the console enabled ?
I can add things back in until I figure out what is failing. 















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Re: [beagleboard] BBB Clone change UART0 to UART4

[Dave]

Thank you. 

I still can't figure out where it is being set incorrectly but I was able 
to use printenv and editenv and saveenv to correct it and I am now booting 
with the correct UART as console. 

On to the next obstacle !!



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Re: [beagleboard] BBB Clone change UART0 to UART4

[Robert Nelson]

On Thu, Jan 24, 2019 at 1:10 AM Dave  wrote:
>
> The BBB Clone board I am trying to get working has had sufficient work that 
> it is now trying to load Linux.
>
> I have u-boot patched to use UART4 as the console.  I have tried to make 
> changes to pass UART4 to linux as the console, without success.
>
> I still get
>
> debug: [console=ttyO0,115200n8 bone_capemgr.uboot_capemgr_enabled=1 
> root=/dev/mmcblk0p1 ro rootfstype=ext4 rootwait coherent_pool=1M 
> net.ifnames=0] ...
>
> from uboot on UART4 just before starting the kernel when I lose output
>
> Where is the console getting set to ttyO0 ?

In this "init_console" function, in the shell environment...

https://github.com/RobertCNelson/Bootloader-Builder/blob/master/patches/v2018.09/0001-am335x_evm-uEnv.txt-bootz-n-fixes.patch#L695-L702

Regards,

-- 
Robert Nelson
https://rcn-ee.com/

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Re: [beagleboard] BBB Clone change UART0 to UART4

[Charles Steinkuehler]

On 1/24/2019 1:10 AM, Dave wrote:
> The BBB Clone board I am trying to get working has had sufficient work that 
> it is now trying to load Linux. 
> 
> I have u-boot patched to use UART4 as the console.  I have tried to make 
> changes to pass UART4 to linux as the console, without success. 
> 
> I still get 
> 
> debug: [console=ttyO0,115200n8 bone_capemgr.uboot_capemgr_enabled=1 
> root=/dev/mmcblk0p1 ro rootfstype=ext4 rootwait coherent_pool=1M 
> net.ifnames=0] ...
> 
> from uboot on UART4 just before starting the kernel when I lose output 
> 
> Where is the console getting set to ttyO0 ? 

Probably the U-Boot default environment.

Hit a key at the U-Boot "countdown" prompt and dump the environment:

> printenv

You can follow along from the "boot" entry until you get to the point
where the kernel command line is being set.  Edit that entry (editenv)
to use UART4 and then boot from the prompt.

Depending on your U-Boot, the default environment may be compiled in,
stored raw on the uSD, or in something like the uEnv.txt file.

-- 
Charles Steinkuehler
char...@steinkuehler.net

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Re: [beagleboard] BBB Clone change UART0 to UART4

[Yiling Cao]

code in uboot? uEnv.txt? kernel cmdline?

On Thu, Jan 24, 2019 at 3:10 PM Dave  wrote:

> The BBB Clone board I am trying to get working has had sufficient work
> that it is now trying to load Linux.
>
> I have u-boot patched to use UART4 as the console.  I have tried to make
> changes to pass UART4 to linux as the console, without success.
>
> I still get
>
> debug: [console=ttyO0,115200n8 bone_capemgr.uboot_capemgr_enabled=1
> root=/dev/mmcblk0p1 ro rootfstype=ext4 rootwait coherent_pool=1M
> net.ifnames=0] ...
>
> from uboot on UART4 just before starting the kernel when I lose output
>
> Where is the console getting set to ttyO0 ?
>
>
>
>
>
>
>
>
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-- 
Yiling Cao
http://ariaboard.com/
http://shanghainovotech.com/

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