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John R. Graham
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Joined: 08 Mar 2005
Posts: 10655
Location: Somewhere over Atlanta, Georgia
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 Posted: Sat Aug 24, 2024 2:44 am Post subject: Xorg Display Size Reporting Error: Raspberry Pi Specific? |
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Got X and KDE working on my shiny new Raspberry Pi 5 with a little xorg.conf.d snippet pulled from one of NeddySeagoon's threads: | Code: | Section "OutputClass"
Identifier "vc4"
MatchDriver "vc4"
Driver "modesetting"
Option "PrimaryGPU" "true"
EndSection |
It's mostly glitch free. However, I've found that the display driver is misreporting (or miscollecting) the display size from my monitor. On my big desktop machine (with an nVidia card), I'm seeing the correct values: | Code: | ~ # xdpyinfo | grep -B2 resolution
screen #0:
dimensions: 2560x1440 pixels (533x302 millimeters)
resolution: 122x121 dots per inch |
But on the Pi 5 with the exact same monitor (I have a KVM switch). I get: | Code: | ~ # xdpyinfo | grep -B2 resolution
screen #0:
dimensions: 2560x1440 pixels (677x381 millimeters)
resolution: 96x96 dots per inch |
Since the size is over-reported, the renderer scales fonts and other GUI elements down on the Pi as compared to my desktop machine.
I was able to supply the correct screen dimensions with another xorg.conf.d snippet: | Code: | Section "Screen"
Identifier "Screen0"
Monitor "Monitor0"
EndSection
Section "Monitor"
Identifier "Monitor0"
VendorName "HP"
ModelName "Z24q G3"
DisplaySize 533 302
EndSection |
I don't yet know if this is necessitated by a driver bug, a video monitor bug, or a hardware limitation in the Pi. Has anyone else had scaling issues like this with the Raspberry Pi?
- John
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 54577
Location: 56N 3W
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| Posted: Sat Aug 24, 2024 6:10 am Post subject: |
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John,
KVM's do some strange things.
Is it OK without the KVM?
Ihope the Pi is not yowr new Flight Control Computer.
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Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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John R. Graham
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Joined: 08 Mar 2005
Posts: 10655
Location: Somewhere over Atlanta, Georgia
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| Posted: Sat Aug 24, 2024 3:40 pm Post subject: |
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Hi Roy,
That's a good point, although this one has been pretty well behaved. In any case, the problem persists with a direct HDMI connection from the Pi to the monitor. I'll haul out another monitor eventually to get another data point.
- John
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 54577
Location: 56N 3W
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| Posted: Sat Aug 24, 2024 8:44 pm Post subject: |
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John,
it's probably not worth the faffing about to debug, never mind fix.
The emergency manual override fixes it for Xorg.
Look in dmesg for the command line. is it wrong there too?
The Pi5 defaults to kerned detection for the console but there is a knob in config.txt to have the Pi firmware do it.
As always, you can do your own thing in cmdline.txt.
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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John R. Graham
Administrator
Joined: 08 Mar 2005
Posts: 10655
Location: Somewhere over Atlanta, Georgia
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| Posted: Sun Aug 25, 2024 10:06 pm Post subject: |
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| NeddySeagoon wrote: | | ... Look in dmesg for the command line. is it wrong there too? |
It's not even present in the command line, which currently is | Code: | | [ 0.000000] Kernel command line: reboot=w coherent_pool=1M 8250.nr_uarts=1 pci=pcie_bus_safe smsc95xx.macaddr=2C:CF:67:51:49:B5 vc_mem.mem_base=0x3fc00000 vc_mem.mem_size=0x40000000 dwc_otg.lpm_enable=0 console=tty root=/dev/sda3 rootfstype=ext4 rootwait cma=256M@256M net.ifnames=0 |
| NeddySeagoon wrote: | | The Pi5 defaults to kerned detection for the console but there is a knob in config.txt to have the Pi firmware do it. |
Do you mean display_auto_detect=1? I've got that set and also disable_fw_kms_setup=0.
- John
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