Raspberry Pi 4 hdmi1 resolution

[HLavaste]

Hi,

I have the following issue.
I have to identical displays. Which ever I plug into hdmi0 will be able to do 1920x1080.
The one connected to hdmi1 will only go as high as 1024x768.

pi@raspberrypi:~ $ uname -sr
Linux 4.19.118-v7l+
pi@raspberrypi:~ $ cat /etc/os-release
PRETTY_NAME="Raspbian GNU/Linux 10 (buster)"
NAME="Raspbian GNU/Linux"
VERSION_ID="10"
VERSION="10 (buster)"
VERSION_CODENAME=buster
ID=raspbian
ID_LIKE=debian


pi@raspberrypi:~ $ xrandr
Screen 0: minimum 320 x 200, current 2048 x 768, maximum 7680 x 7680
HDMI-1 connected primary 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
1920x1080 60.00
1024x768 60.00*
800x600 60.32 56.25
848x480 60.00
640x480 59.94
HDMI-2 connected 1024x768+1024+0 (normal left inverted right x axis y axis) 0mm x 0mm
1024x768 60.00*
800x600 60.32 56.25
848x480 60.00
640x480 59.94

If I use raspi-config, I can only modify hdmi0, but not hdmi1.
Am I missing something very simple here?

Thanks
Heikki

[FTrevorGowen]

Hi,

...

If I use raspi-config, I can only modify hdmi0, but not hdmi1.
Am I missing something very simple here?

Thanks
Heikki

For the P4B you can apply config.txt options for either port but that has to be explicitly specified. See the "Note for Raspberry Pi4B users" in the "HDMI mode options" section in this https://www.raspberrypi.org/documentati ... t/video.md
Trev.

[6by9]

That sounds like for some reason the Pi can't read the EDID from the monitor, so it drops back to defaults as you list.
Looking at the list from xrandr I think the same is true of HDMI0, but you've used raspi-config to force the mode to 1080p60, so it's added an entry to config.txt that then gets added to the kernel config.

You can add

Code: Select all

hdmi_group:1=1
hdmi_mode:1=16

to /boot/config.txt to force HDMI1 to 1080p60. I suspect you'll already have lines

Code: Select all

hdmi_group=1
hdmi_mode=16

that have been added by raspi-config.

[HLavaste]

Hi,

Thank you all for your help so far.
Turns out, 4kp60 was enabled and there was not enough power to go around.
Disabled that and now I have the option for 1920x1080, both monitors.
Still, the issue remains following:
When I change the mode to 1920, hdmi0 goes black and hdmi1 changes to 1080p.
After a few seconds, hdmi1 reverts back to lower res as well.
I've set a group in boot/config.txt to set group 1 and mode 16.
I've also tried group 2 and mode 82.

Any tips on how to troubleshoot further?
Thanks in advance.

Heikki

[aBUGSworstnightmare]

Hi,

Thank you all for your help so far.
Turns out, 4kp60 was enabled and there was not enough power to go around.
Disabled that and now I have the option for 1920x1080, both monitors.
Still, the issue remains following:
When I change the mode to 1920, hdmi0 goes black and hdmi1 changes to 1080p.
After a few seconds, hdmi1 reverts back to lower res as well.
I've set a group in boot/config.txt to set group 1 and mode 16.
I've also tried group 2 and mode 82.

Any tips on how to troubleshoot further?
Thanks in advance.

Heikki

So, did you add below to config.txt (as already suggested by 6by9)?

Code: Select all

hdmi_group:0=1
hdmi_mode:0=16

hdmi_group:1=1
hdmi_mode:1=16

[HLavaste]

Hi,

I have indeed.

hdmi_group:0=1
hdmi_mode:0=16

hdmi_group:1=1
hdmi_mode:1=16


When I do a reboot, hdmi0 comes up @ 1920x1080, hdmi1 @ 1024x 768.

pi@raspberrypi:~ $ xrandr -q
Screen 0: minimum 320 x 200, current 2944 x 1080, maximum 7680 x 7680
HDMI-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
1920x1080 60.00*
1024x768 60.00
800x600 60.32 56.25
848x480 60.00
640x480 59.94
HDMI-2 connected 1024x768+1920+0 (normal left inverted right x axis y axis) 0mm x 0mm
1920x1080 60.00
1024x768 60.00*
800x600 60.32 56.25
848x480 60.00
640x480 59.94

If I change the second display, either xrandr or from gui, the display just goes black.

[6by9]

Can you provide the output of
cat /proc/cmdline
Please?

[andrum99]

Turns out, 4kp60 was enabled and there was not enough power to go around.

If you have power problems then all bets are off. What are you powering the Pi from? The official power supply is recommended.

[HLavaste]

Hi,

Power supply is the official one.
I seem to have some other performance issues with this box as well
I've had the pi for some months now but only used it without the GUI so far.
Today, I tried to watch a video from youtube and had a pair of bluetooth headphones connected.
Both video and audio were running at a slower speed and it reminded me of the times when my sony walkman ran out of batteries.
I'm guessing the box should be able to handle 1080p video from a browser?
Anyways, here is the cmcline output.

pi@raspberrypi:~ $ cat /proc/cmdline
coherent_pool=1M 8250.nr_uarts=0 cma=64M snd_bcm2835.enable_compat_alsa=0 snd_bcm2835.enable_hdmi=1 snd_bcm2835.enable_headphones=1 cma=256M video=HDMI-A-1:1920x1080M@60 video=HDMI-A-2:1920x1080M@60 smsc95xx.macaddr=DC:A6:32:81:F8:9B vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000 console=ttyS0,115200 console=tty1 root=PARTUUID=97709164-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles

[6by9]

So that cmdline is as I'd expect, but you have now got me querying how well the kernel handles having two video= entries in the command line. Do they override one another? Although then I'd expect them to apply to the last one defined. I'll have a look on Monday if I remember.

My larger query is why you're having to override the mode at all. Your Pi appears to be unable to read the EDID from either monitor and is therefore providing the default config. It's difficult to say if that is a hardware or software issue, and if hardware whether it's the monitor, cable, or Pi.

Can you provide the output from "xrandr --verbose" please? And confirm you don't have any other lines in config.txt starting "hdmi_" (eg hdmi_force_hotplug or hdmi_ignore_edid). It may be easier to copy/paste the whole of config.txt here (inside a set of code tags please).