Rotating a 21:9 screen to work vertically

Question

Any help would be appriciated!

So I recently got a LG 25UM58-P 25-Inch 21:9 UltraWide monitor and I'm having some issues getting it to work vertically with a raspberry Pi 3.

I'm using the below config.txt to set the resolution on boot.

hdmi_ignore_cec_init=1
hdmi_drive=2
disable_overscan=1

hdmi_ignore_edid=0xa5000080
hdmi_group=2
hdmi_mode=87
hdmi_timings=2560 1 64 64 96 1080 1 3 10 31 0 0 1 60 0 185580000 8

config_hdmi_boost=4

max_framebuffer_width=2560
max_framebuffer_height=1280
framebuffer_width=2560
framebuffer_height=1080

gpu_mem=128
arm_freq=900
gpu_freq=275
sdram_freq=500
hdmi_pixel_freq_limit=400000000
avoid_pwm_pll=1

This works fine when the screen is used horizontally as you can see below:

But when I add display_rotate=3 to the config.txt I get the below:

its rotating it fine but the resolutions gets lost.

Answer 1

Thanks for info Milliways,

your comment made me check over my current configuration and play around with it.

The below actually works:

display_rotate=3
hdmi_ignore_cec_init=1
hdmi_drive=2
disable_overscan=1

hdmi_ignore_edid=0xa5000080
hdmi_group=2
hdmi_mode=87
hdmi_timings=2560 1 64 64 96 1080 1 3 10 31 0 0 1 60 0 185580000 8

config_hdmi_boost=4

max_framebuffer_width=2560
max_framebuffer_height=1080
framebuffer_width=1280
framebuffer_height=2560

gpu_mem=128
arm_freq=900
gpu_freq=275
sdram_freq=500
hdmi_pixel_freq_limit=400000000
avoid_pwm_pll=1

So I think the issue was as I was rotating the screen I needed to change the direction of the framebuffer.

Answer 2

I don't know exactly why your screen is behaving this way, unless it is the excessive commands you have in the config file.

All you need to do is include rotate=3 in config.sys.

The effect of this is NOT to change the screen, which continues to operate in the same mode. All it does is cause the Pi to set pixels in the framebuffer in a different manner.

If the Pi will not detect the correct mode for your screen Create Custom HDMI modes may help.

Another possibility is that your screen has an inbuilt orientation detector, in which case you should NOT try to specify resolution, but let the Pi detect, and not include rotate=3.

See https://raspberrypi.stackexchange.com/a/62147/8697, which includes a script I use to rotate the screen.