Changing multi-user default resolution when booting and after

Robotics & Edge Computing Jetson & Embedded Systems Jetson TX2
1

Hi,

How can I set frame buffer default or max resolution in multi-user boot mode (no graphics)? I figured I can do it with framebuffer after device is booted, but not when it is booting.

I tried looking into kernel parameters, but with no success. I extracted dts files inspired by this thread, but I could not find any documentation about it therefore I dropped the idea.

extracted.dts.zip (66.6 KB)

I tried also changing boot parameters (or deleting APPEND part) in /boot/extlinux/extlinux.conf with no success. When APPEND part was deleted kernel still booted with a bunch of default parameters.

Currently to I’m. using:

#!/usr/bin/env bash
 
echo 4 >/sys/class/graphics/fb0/blank # TURN SCREEN OFF
echo "D:1920x1080p-60" > /sys/class/graphics/fb0/mode # SET     RESOLUTION
echo -e '\033[9;0]' > /dev/tty1 # DISABLE SLEEP
echo 0 > /sys/class/graphics/fb0/blank # TUNR SCREEN ON

Setup:
Jetson tx2 with 4.9.140-tegra.

My /proc/cmdline:

console=ttyS0,115200 androidboot.presilicon=true 
firmware_class.path=/etc/firmware root=/dev/mmcblk0p1 rw rootwait 
rootfstype=ext4 console=ttyS0,115200n8 console=tty0 fbcon=map:0             
net.ifnames=0 isolcpus=1-2  video=tegrafb no_console_suspend=1 
earlycon=uart8250,mmio32,0x3100000 nvdumper_reserved=0x2772e0000 
gpt tegra_fbmem2=0x800000@0x9607d000 lut_mem2=0x2008@0x9607a000 
tegra_fbmem3=0x800000@0x96882000 lut_mem3=0x2008@0x9687f000 
usbcore.old_scheme_first=1 tegraid=18.1.2.0.0 maxcpus=6 boot.slot_suffix= 
boot.ratchetvalues=0.2031647.1 bl_prof_dataptr=0x10000@0x275840000 
sdhci_tegra.en_boot_part_access=1

Cheers

3

Hi,

Could you describe

  1. What is your expected resolution?

  2. What is current resolution that tx2 gives you?

  3. Which software release are you using? Some kernel command line are appened by bootloader so deleting extlinux may not remove them all.

4

Hey,

  1. Expected resolution 1920x1080-60p
  2. Current resolution 3840-2160-30p, it depends what kind of screen I attach. If max resolution for screen is 4k30p then it will show in 4k,30p if it is 1080p60 then it will show full hd. And each time I unplug and plug back in it goes to the max resolution.
  3. L4t 32.4.3
5

Hi,

It is normal because the driver wants to give you the best resolution it can support.
If lacking of display manager (GUI), then the mode you set is not able to be recorded so each reboot/hotplug will set it back.

6

Currently my solution is to poll the /sys/class/graphics/fb0/mode file for changes and when that happens set my desired resolution and frame rate. Is there some other way where I could lock in to specific resolution? I don’t need to change resolution at all.

Can you please elaborate on the mode you set is not able to be recorded .

7

How can I set frame buffer default or max resolution in multi-user boot mode (no graphics)?

Because you said there is no GUI here, what you are using is called framebuffer console. And fb console is not able to record the display mode you once set as “display setting” in GUI.

Also, how to configure the display console depends on the driver of each platform. Thus, using some methods from x86 ubuntu may not help here because tegra display controller driver does not support them.

You can try to use some generic API/tool for your case so that no need to change resolution through the sysfs.
For example, you can try to use fbset.

https://manpages.debian.org/stretch/fbset/fbset.1.en.html

8

Yeah, I tried using that, but display image is distorted. Therefore I’m just writing in fb0/mode file “1920x1080p60” and it works. If I use fbset It is repeating image multiple times on the screen and I can see on the display settings it has failed to negotiate resolution and frame rate.

Command: fbset -fb /dev/fb0 -g 1920 1080 1920 1080 32 --timings 6734 148 88 36 4 44 5 -pixclock 6734

Output:

mode "1920x1080-60"
    # D: 148.500 MHz, H: 67.500 kHz, V: 60.000 Hz
    geometry 1920 1080 1920 1080 32
    timings 6734 148 88 36 4 44 5
    hsync high
    vsync high
    nonstd 1
    accel true
    rgba 8/16,8/8,8/0,8/24
endmode

When using the bash script provided earlier I get:

mode "1920x1080-60"
    # D: 148.500 MHz, H: 67.500 kHz, V: 60.000 Hz
    geometry 1920 1080 1920 1080 32
    timings 6734 148 88 36 4 44 5
    hsync high
    vsync high
    nonstd 1
    accel true
    rgba 8/16,8/8,8/0,8/24
endmode

Both are exactly the same. Bash scripts provides desired output, fbset fails provide desired output.

And none of these records the screen resolution.

When GUI is used, how does it records the settings for the user/screen/output port? Perhaps I could simulate something like that. I would be happy if you just pointed me to the right direction.

9

Hi,

Sorry that I don’t know how gnome desktop saves these parameters.

As for your latest comment here, please note that tegra does not accept a mode created from userspace and only want the modes from edid or dts. Thus, I guess fbset is trying to add a new mode and get rejected by driver.