2560x1440

I have a Raspberry Pi 4 and a Dell P2720DC 27" monitor. After spending most of today fighting with config/txt to try and make the combination usable, I am ready to throw the towel in and post on the forums.

ScrModes reports:

1. Mode: 2560 × 1440 @ 60Hz
   startmode
   mode_name:2560 × 1440
   x_res:2560
   y_res:1440
   pixel_rate:241500
   h_timings:32,80,0,2560,0,48
   v_timings:5,33,0,1440,0,3
   sync_pol:2
   endmode

My config/txt file (modified several hundred times today):
fake_vsync_isr=1
framebuffer_swap=0
gpu_mem=128
init_emmc_clock=100000000
ramfsfile=CMOS
ramfsaddr=0×508000
kernel=RISCOS.IMG
disable_overscan=1
max_framebuffer_width=2560
max_framebuffer_height=1440
hdmi_pixel_freq_limit=250000000
hdmi_cvt=2560 1440 60
framebuffer_width=2560
framebuffer_height=1440
hdmi_timings=2560 0 48 32 80 1440 0 3 5 33 0 0 0 60 0 221184000 3

[pi4]
enable_gic=1

I’d be indebted to someone who can tell me where I’m going wrong, because the blurry text on my display is currently almost unreadable. Chris Hall’s ScrHelp utility shows RISC OS at 2560×1440 C16M, whilst the GPU at 1366×768 32bpp. So my settings are obviously wrong and there is no specific hdmi_mode for 2560×1440.

Grateful for any insight!

My AOC’s EDID does not advertise 2540×1440 as the default resolution either.

This line should help in config/txt.

hdmi_ignore_edid 0xa5000080

A lower pixel rate MDF was used here.

# 2560 x 1440 (60.00Hz) INT RBlank 32bit (CVT)
startmode
mode_name: 2560 x 1440  cvt
x_res:2560
y_res:1440
pixel_rate:121000
h_timings:32,80,0,2560,0,48
v_timings:5,13,0,1440,0,3
sync_pol:3
endmode

I made an MDF for my AOC Q2790 rather than using the auto settings, the 2560×1440 mode is similar to David’s above (except the vertical back porch is 33 rather than 13), I’ve not needed to ignore EDID for this monitor, but I do explicitly request this mode in the config/txt.

[pi4]
enable_gic=1
hdmi_enable_4kp60=1

# Pi4B overclock
#arm_freq=2000
#gpu_freq=750
#over_voltage=6

[all]
disable_overscan=1
hdmi_blanking=1
hdmi_drive=2
hdmi_force_edid_audio=1
fake_vsync_isr=1
framebuffer_swap=0
gpu_mem=64
init_emmc_clock=100000000
ramfsfile=CMOS
ramfsaddr=0x508000
kernel=RISCOS.IMG
hdmi_group=2
hdmi_mode=87
hdmi_cvt=2560 1440 60 3 0 0 1
max_framebuffer_width=2560
max_framebuffer_height=1440
hdmi_pixel_freq_limit=250000000

ARMX6 machines from R-Comp include an MDF which works perfectly with my 2560×1440 monitor as 60Hz. It might be worth asking Andrew about it.

My MDF is actually based on the 4K compatible MDF which came with the ARMx6.

In the end, the main thing I needed was:

hdmi_ignore_edid 0xa5000080

… as advised by David P.

I still had to add:

max_framebuffer_width=2560
max_framebuffer_height=1440

…to config/txt.

And I created a suitable MDF. I used the info reported from ScrModes to make my MDF.

Can someone explain where the fault lies? I thought we were happily in EDID land these days. I might have blamed my Dell display for improperly reporting its EDID, except that RISC OS did know that my maximum resolution was 2560×1440, as proven with the *SaveModeFile I had done before any config/txt changes.

Config/txt:

fake_vsync_isr=1
framebuffer_swap=0
gpu_mem=64
disable_overscan=1
hdmi_group=2
hdmi_drive=2
hdmi_blanking=1
hdmi_mode=87
hdmi_cvt=2560 1440 60 3 0 0 1
max_framebuffer_width=2560
max_framebuffer_height=1440
hdmi_pixel_freq_limit=400000000
init_emmc_clock=100000000
ramfsfile=CMOS
ramfsaddr=0x508000
kernel=RISCOS.IMG

[pi4]
enable_gic=1
over_voltage=6
arm_freq=2000
gpu_freq=750

Monitor type: Auto

There’s another way to do this; I have an LG (3840 × 1600) monitor.

My config/txt

fake_vsync_isr=1 
framebuffer_swap=0 
gpu_mem=256 
init_emmc_clock=100000000 
ramfsfile=CMOS 
ramfsaddr=0x508000 
kernel=RISCOS.IMG

[pi4] 

enable_gic=1 

hdmi_enable_4kp60=1 

disable_overscan=1 

#hdmi_drive=1 

hdmi_ignore_edid_audio=1 

hdmi_group=0

I created an Obey text file with the following configuration information:

WimpMode X3440 Y1440 C16M EX1 EY1 F75 

I then went to !Configure → boot –> run; this opens the “run at start-up” window, where I drag and drop the obey file, so it runs at start-up.

It works for me. ;)

Can someone explain where the fault lies? I thought we were happily in EDID land these days.

So we thought, further ahead, but not quite there yet.