linuxcnc-2.8.0-pi4.img - no USB on raspberry pi 4 - 8GB & 2GB

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12 Jan 2021 07:03 #195017 by tjtr33
short story: on my RPI4 4G the loss of usb is is due to >= 4G mem.
i have a full install now by adding
total_mem=3072
to /boot/config.txt
i got the fix from
www.cnx-software.com/2019/11/04/raspberr...ork-on-ubuntu-19-10/

I did the above
BEFORE installing linuxcnc-uspace
AFTER rt kernel install

( i tried installing rpi-eeprom but it was already latest)

the bad news, chromium browser wont run
complaing no suitable sandbox

i have no browser right now
but can run latency tests

i edited cmdline.txt and added
isolcpus=1,2,3 idle=poll

then for Samco's time spike
sudo apt-get install ntp

rebooted fine with usb mouse and kbd and wifi

10 minutes of aletency-histogram --base 50000 --servo 1000000
with 4 glcgears
has
base -44 +39 servo -152 +158

there's hope for rpi software stepping, esp if dblstep is fixed ( if reset pins are available... working on it.. NAP NAM not a programmer not a monkey )
tomp

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12 Jan 2021 08:48 #195025 by andypugh
apt-get reinstall chromium will get the web browser back (but might leave the tool bar icon lunching Dillo...)

There might be more going on here than we at first thought.

The first fix was to add the USB eeprom firmware loader, as on the newer boards that it held in the OS not a ROM.
But if restricting the memory changes the behaviour, then something else is at play.

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12 Jan 2021 09:51 #195028 by antage

i tried installing rpi-eeprom but it was already latest


Could you post 'sudo rpi-eeprom-update' command output?

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12 Jan 2021 13:33 #195047 by tjtr33
longer testing with software stepgens shows rpi4 not suitable. I tried longer and longer Base threads and even at 100uS base I still get Unexpected Real Time delays errors. Base 100us servo 1000us, ntpd, isolcpus-1,2,3 idle=poll and ferror = 0.07. Its not up to software stepgen IMO. It is suited to use with hardware stepgens. TomP

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12 Jan 2021 13:43 #195050 by andypugh
Yes, I really only ever expected it to be used with Mesa Ethernet or SPI cards when I made the images / kernels.

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14 Jan 2021 17:10 #195340 by andypugh
Can those with this problem please state exactly which model of Pi they are using?

One possible problem is that the 8GB Pi needs a 64bit kernel if it is going to address more than 4GB.

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16 Jan 2021 10:37 - 16 Jan 2021 11:12 #195525 by johnp
I have the 8GB Pi4 and lose USB when booting linuxcnc-2.8.0-pi4.img. I also get the other errors people have mentioned.

Stock Pi OS works just fine.

I haven't tried restricting the memory to <4GB yet.
Last edit: 16 Jan 2021 11:12 by johnp.

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16 Jan 2021 20:26 #195572 by andypugh

I have the 8GB Pi4 and lose USB when booting linuxcnc-2.8.0-pi4.img.


Have you tried any of the updated kernels that I keep building?

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18 Jan 2021 11:06 - 18 Jan 2021 11:19 #195767 by johnp


Have you tried any of the updated kernels that I keep building?


Sorry but where do I find these updated kernels ?

In case I have tried the instructions here again
linuxcnc.org/docs/2.8/html/getting-start...lling_on_raspbian_10

but after Step 6.
added total_mem=3072 to /boot/config.txt
rebooted

before completing Step 7.

I now have USB working and can run the latency test.



sudo rpi-eeprom-update
BCM2711 detected
VL805 firmware in bootloader EEPROM
BOOTLOADER: up-to-date
CURRENT: Thu 03 Sep 2020 12:11:43 PM UTC (1599135103)
LATEST: Thu 03 Sep 2020 12:11:43 PM UTC (1599135103)
FW DIR: /lib/firmware/raspberrypi/bootloader/default
VL805: up-to-date
CURRENT: 000138a1
LATEST: 000138a1

uname -a
Linux raspberrypi 4.19.71-rt24-v7l+ #1 SMP PREEMPT RT Fri Jan 1 21:15:16 GMT 2021 armv7l GNU/Linux
Last edit: 18 Jan 2021 11:19 by johnp.

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18 Jan 2021 12:07 - 18 Jan 2021 12:09 #195774 by andypugh

but after Step 6.
added total_mem=3072 to /boot/config.txt
rebootedx


I am confused now, all the links to the max memory issue only mentioned 64 bit kernels.

I will have one last go tonight: Recreate the SD card image with the latest kernel, then make a second version with the memory limit in the config file.
Last edit: 18 Jan 2021 12:09 by andypugh.

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