Can't get native 2560x1440 resolution on Dell monitor (under Xorg, Wayland, Nouveau or proprietary)

Hi all,

I have Fedora 32 installed on my Dell 7779 laptop, which has an Intel HD Graphics 620 card and an NVIDIA GeForce 940MX card. I recently bought a Dell P2720D monitor, which has a resolution of 2560x1440 @ 60Hz. This resolution works fine on my Windows partition, so I know the cards and HDMI cable are working. But I can’t get this resolution on Fedora.

At first I was using Nouveau and Wayland. The correct resolution did not appear in Settings->Displays, and I saw in posts such as this that adding resolutions under Wayland is pretty involved. So I installed the proprietary NVIDIA driver through rpmfusion, thinking this might fix things by itself and if not at least I’d be back in Xorg and adding a resolution might be easier.

Installing the NVIDIA driver did not change anything, so I tried what I’ve seen in several posts:
gtf 2560 1440 60
xrandr --newmode "2560x1440_60.00" 311.83 2560 2744 3024 3488 1440 1441 1444 1490 -HSync +Vsync
xrandr --addmode HDMI-1 "2560x1440_60.00"
xrandr --output HDMI-1 --mode "2560x1440_60.00"
This last command results in a brief blank screen, no resolution change, and the error message xrandr: Configure crtc 0 failed. These steps also result in the new resolution showing up in Settings->Displays, but selecting it there similarly results in a silent reversion to the previous resolution. (I read in some posts that underscores in mode names can be a problem, so I tried all the above with the name “newname” with the same results.)

Below are the results of cat /sys/class/drm/card0-HDMI-A-1/edid | edid-decode. As you can see, the correct resolution does appear as DTD 1. Any ideas? Because the monitor and cards all seem mainstream, I figure I’m missing something basic.


00 ff ff ff ff ff ff 00 10 ac 01 d1 53 4c 47 30
13 1e 01 03 80 3c 22 78 ea 4c 55 a9 55 4d 9d 26
0f 50 54 a5 4b 00 81 00 b3 00 d1 00 71 4f a9 40
81 80 d1 c0 01 01 56 5e 00 a0 a0 a0 29 50 30 20
35 00 55 50 21 00 00 1a 00 00 00 ff 00 35 53 46
59 53 30 33 0a 20 20 20 20 20 00 00 00 fc 00 44
45 4c 4c 20 50 32 37 32 30 44 0a 20 00 00 00 fd
00 31 4b 1d 71 1c 00 0a 20 20 20 20 20 20 01 ad

02 03 1a b1 4f 90 05 04 03 02 07 16 01 06 11 12
15 13 14 1f 65 03 0c 00 10 00 02 3a 80 18 71 38
2d 40 58 2c 45 00 55 50 21 00 00 1e 01 1d 80 18
71 1c 16 20 58 2c 25 00 55 50 21 00 00 9e 7e 39
00 a0 80 38 1f 40 30 20 3a 00 55 50 21 00 00 1a
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 28

----------------

Block 0, Base EDID:
  EDID Structure Version & Revision: 1.3
  Vendor & Product Identification:
    Manufacturer: DEL
    Model: 53505
    Serial Number: 809978963
    Made in: week 19 of 2020
  Basic Display Parameters & Features:
    Digital display
    Maximum image size: 60 cm x 34 cm
    Gamma: 2.20
    DPMS levels: Standby Suspend Off
    RGB color display
    First detailed timing is preferred timing
  Color Characteristics:
    Red  : 0.6611, 0.3320
    Green: 0.3037, 0.6132
    Blue : 0.1494, 0.0595
    White: 0.3134, 0.3291
  Established Timings I & II:
    IBM     :   720x400    70.082 Hz   9:5    31.467 kHz  28.320 MHz
    DMT 0x04:   640x480    59.940 Hz   4:3    31.469 kHz  25.175 MHz
    DMT 0x06:   640x480    75.000 Hz   4:3    37.500 kHz  31.500 MHz
    DMT 0x09:   800x600    60.317 Hz   4:3    37.879 kHz  40.000 MHz
    DMT 0x0b:   800x600    75.000 Hz   4:3    46.875 kHz  49.500 MHz
    DMT 0x10:  1024x768    60.004 Hz   4:3    48.363 kHz  65.000 MHz
    DMT 0x12:  1024x768    75.029 Hz   4:3    60.023 kHz  78.750 MHz
    DMT 0x24:  1280x1024   75.025 Hz   5:4    79.976 kHz 135.000 MHz
  Standard Timings:
    DMT 0x1c:  1280x800    59.810 Hz  16:10   49.702 kHz  83.500 MHz
    DMT 0x3a:  1680x1050   59.954 Hz  16:10   65.290 kHz 146.250 MHz
    DMT 0x45:  1920x1200   59.885 Hz  16:10   74.556 kHz 193.250 MHz
    DMT 0x15:  1152x864    75.000 Hz   4:3    67.500 kHz 108.000 MHz
    DMT 0x33:  1600x1200   60.000 Hz   4:3    75.000 kHz 162.000 MHz
    DMT 0x23:  1280x1024   60.020 Hz   5:4    63.981 kHz 108.000 MHz
    DMT 0x52:  1920x1080   60.000 Hz  16:9    67.500 kHz 148.500 MHz
  Detailed Timing Descriptors:
    DTD 1:  2560x1440   59.951 Hz  16:9    88.787 kHz 241.500 MHz (597 mm x 336 mm)
                 Hfront   48 Hsync  32 Hback  80 Hpol P
                 Vfront    3 Vsync   5 Vback  33 Vpol N
    Display Product Serial Number: '5SFYS03'
    Display Product Name: 'DELL P2720D'
  Display Range Limits:
    Monitor ranges (GTF): 49-75 Hz V, 29-113 kHz H, max dotclock 280 MHz
  Extension blocks: 1
Checksum: 0xad

----------------

Block 1, CTA-861 Extension Block:
  Revision: 3
  Underscans PC formats by default
  Supports YCbCr 4:4:4
  Supports YCbCr 4:2:2
  Native detailed modes: 1
  Video Data Block:
    VIC  16:  1920x1080   60.000 Hz  16:9    67.500 kHz 148.500 MHz (native)
    VIC   5:  1920x1080i  60.000 Hz  16:9    33.750 kHz  74.250 MHz
    VIC   4:  1280x720    60.000 Hz  16:9    45.000 kHz  74.250 MHz
    VIC   3:   720x480    59.940 Hz  16:9    31.469 kHz  27.000 MHz
    VIC   2:   720x480    59.940 Hz   4:3    31.469 kHz  27.000 MHz
    VIC   7:  1440x480i   59.940 Hz  16:9    15.734 kHz  27.000 MHz
    VIC  22:  1440x576i   50.000 Hz  16:9    15.625 kHz  27.000 MHz
    VIC   1:   640x480    59.940 Hz   4:3    31.469 kHz  25.175 MHz
    VIC   6:  1440x480i   59.940 Hz   4:3    15.734 kHz  27.000 MHz
    VIC  17:   720x576    50.000 Hz   4:3    31.250 kHz  27.000 MHz
    VIC  18:   720x576    50.000 Hz  16:9    31.250 kHz  27.000 MHz
    VIC  21:  1440x576i   50.000 Hz   4:3    15.625 kHz  27.000 MHz
    VIC  19:  1280x720    50.000 Hz  16:9    37.500 kHz  74.250 MHz
    VIC  20:  1920x1080i  50.000 Hz  16:9    28.125 kHz  74.250 MHz
    VIC  31:  1920x1080   50.000 Hz  16:9    56.250 kHz 148.500 MHz
  Vendor-Specific Data Block (HDMI), OUI 00-0C-03:
    Source physical address: 1.0.0.0
  Detailed Timing Descriptors:
    DTD 2:  1920x1080   60.000 Hz  16:9    67.500 kHz 148.500 MHz (597 mm x 336 mm)
                 Hfront   88 Hsync  44 Hback 148 Hpol P
                 Vfront    4 Vsync   5 Vback  36 Vpol P
    DTD 3:  1920x1080i  60.000 Hz  16:9    33.750 kHz  74.250 MHz (597 mm x 336 mm)
                 Hfront   88 Hsync  44 Hback 148 Hpol P
                 Vfront    2 Vsync   5 Vback  15 Vpol P Vfront +0.5 Odd Field
                 Vfront    2 Vsync   5 Vback  15 Vpol P Vback  +0.5 Even Field
    DTD 4:  2048x1080   59.998 Hz 256:135  66.658 kHz 147.180 MHz (597 mm x 336 mm)
                 Hfront   48 Hsync  32 Hback  80 Hpol P
                 Vfront    3 Vsync  10 Vback  18 Vpol N
Checksum: 0x28
1 Like

I figured it out. The gtf utility was giving me bad modelines. edid-decode --xmodeline gave me the correct modeline for DTD 1.

1 Like

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