On Mar 10, 2021, at 8:53 AM, Richard Miller <9f...@hamnavoe.com> wrote:
>> That is, if I plug into a ~10 year old Vizio television
>> everything works fine at a reasonable resolution (1280x1024? I haven't yet
>> figured
>> out which utility to use to query display properties)
>
> Here's a simple way:
>
> term% echo `{dd -if /dev/screen -bs 64 -count 1}
>
>> , but if I plug it into a Dell
>> S2817Q the monitor says "No signal detected."
>
> That's a 4k monitor, I think. The native resolution is probably too big
> to fit in the virtual area allowed for the kernel frame buffer. (Lack of
> foresight - monitors were smaller when 9pi was first done.)
>
> I'll see about fixing that soon. Meanwhile, you should be able to use
> hdmi_group and hdmi_mode settings in config.txt to request a lower resolution.
> Or add something like "vgasize=1600x1200x16" to the command line in
> cmdline.txt -
> either method should work.
Not sure how things are different in pi4+pi9 but I was able to get 4K@20Hz
under plan9 back in 2014 on the original pi. Not sure I can find that
SDcard now but the settings were based on what I gleaned from this thread:
https://www.raspberrypi.org/forums/viewtopic.php?t=79330
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