Nouveau DRM failure on 5120x1440 screen with 5.8/5.9 kernel

[Byron Stanoszek]

I'm having a problem with both the 5.8 and 5.9 kernels using the nouveau DRM
driver. I have a laptop with a VGA card (specs below) connected to a 5120x1440
screen. At boot time, the card correctly detects the screen, tries to allocate
fbdev fb0, then the video hangs completely for 15-30 seconds until it goes
blank.

This used to work in Linux 5.7 and earlier, although it allocated a 3840x1080
fb instead of a 5120x1440. I've attached the full dmesg. I tried commands like
video=DP-2:3840x1080 but it doesn't help.

Linux 5.8 boots without hanging if the laptop is not connected to the 5120x1440
screen.


PCI specs:

01:00.0 0300: 10de:0dfc (rev a1)
01:00.0 VGA compatible controller: NVIDIA Corporation GF108GLM [NVS 5200M] (rev a1)


xrandr available resolutions reported (from Linux 5.7 using Xorg):

Screen 0: minimum 320 x 200, current 5120 x 1440, maximum 16384 x 16384
LVDS-1 unknown connection (normal left inverted right x axis y axis)
    1600x900      59.99 +  40.00
    5120x1440     60.00
    1360x1020     73.97
    1152x864      59.97
    1024x768      59.95
    800x600       59.96
    640x480       59.94
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 5120x1440+0+0 (normal left inverted right x axis y axis) 1200mm x 340mm panning 5120x1440+0+0
    3840x1080     59.97 +
    5120x1440     29.98*
    2560x1080     60.00    59.94    59.98
    1920x1080     60.00    60.00    50.00    59.94
    1920x1080i    60.00    50.00    59.94
    1600x1200     60.00
    1280x1024     75.02    60.02
    1280x800      59.81
    1152x864      75.00
    1280x720      60.00    50.00    59.94
    1024x768      75.03    60.00
    800x600       75.00    60.32
    720x576       50.00
    720x480       60.00    59.94
    640x480       75.00    60.00    59.94
    720x400       70.08
HDMI-1 disconnected (normal left inverted right x axis y axis)
VGA-1 disconnected (normal left inverted right x axis y axis)

I'm currently using 5120x1440 at 30. 60 Hz isn't available. But look below:


xrandr resolutions from Linux 5.9 (even though screen is still blank):

Screen 0: minimum 320 x 200, current 5120 x 1440, maximum 16384 x 16384
LVDS-1 unknown connection (normal left inverted right x axis y axis)
    1600x900      59.99 +  40.00
    5120x1440     60.00
    1360x1020     73.97
    1152x864      59.97
    1024x768      59.95
    800x600       59.96
    640x480       59.94
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 5120x1440+0+0 (normal left inverted right x axis y axis) 1200mm x 340mm panning 5120x1440+0+0
    5120x1440     59.98 +  29.98*
    3840x1080     59.97 +
    2560x1080     60.00    59.94    59.98
    1920x1080     60.00    60.00    50.00    59.94
    1920x1080i    60.00    50.00    59.94
    1600x1200     60.00
    1280x1024     75.02    60.02
    1280x800      59.81
    1152x864      75.00
    1280x720      60.00    50.00    59.94
    1024x768      75.03    60.00
    800x600       75.00    60.32
    720x576       50.00
    720x480       60.00    59.94
    640x480       75.00    60.00    59.94
    720x400       70.08
HDMI-1 disconnected (normal left inverted right x axis y axis)
VGA-1 disconnected (normal left inverted right x axis y axis)


Let me know if you need additional debug information/etc.

Thanks,
  -Byron
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