我有一台运行 15.04 的 Thinkpad T440s，配有 Intel HD 4400 显卡。我刚买了一台 4K 显示器（戴尔 P2415Q）。根据 HD4400 的规格，我应该能够以 30hz 的频率驱动这台显示器，分辨率为 4K。我使用这台电脑就是为了实现这一点。请注意，我是通过显示端口连接的。
运行 xrandr 会得到
Screen 0: minimum 8 x 8, current 4480 x 1440, maximum 32767 x 32767
eDP1 connected primary 1920x1080+0+360 (normal left inverted right x axis y axis) 309mm x 173mm
1920x1080 60.0*+ 59.9
1680x1050 60.0 59.9
1600x1024 60.2
1400x1050 60.0
1280x1024 60.0
1440x900 59.9
1280x960 60.0
1360x768 59.8 60.0
1152x864 60.0
1024x768 60.0
800x600 60.3 56.2
640x480 59.9
DP1 connected 2560x1440+1920+0 (normal left inverted right x axis y axis) 527mm x 296mm
3840x2160 60.0 +
2560x1440 60.0*
2048x1280 60.0
1920x1200 59.9
1920x1080 60.0 60.0 50.0 59.9 30.0 25.0 24.0 30.0 24.0
1920x1080i 60.1 50.0 60.0
1600x1200 60.0
1600x900 60.0
1280x1024 75.0 60.0
1152x864 75.0
1280x720 60.0 50.0 59.9
1024x768 75.1 60.0
800x600 75.0 60.3
720x576 50.0
720x480 60.0 59.9
640x480 75.0 60.0 59.9
720x400 70.1
DP2 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
看起来我需要添加一种模式来以 30 Hz 的频率运行 3840x2160。
cvt 3840 2160 30
# 3840x2160 29.98 Hz (CVT) hsync: 65.96 kHz; pclk: 338.75 MHz
Modeline "3840x2160_30.00" 338.75 3840 4080 4488 5136 2160 2163 2168 2200 -hsync +vsync
程序：
xrandr --newmode "3840x2160_30.00" 338.75 3840 4080 4488 5136 2160 2163 2168 2200 -hsync +vsync
xrandr --verbose --addmode DP1 "3840x2160_30.00"
最后：
xrandr --output DP1 --mode "3840x2160_30.00"
当我这样做时，显示器闪烁一秒钟，然后回到 2560x1440 @ 60hz。再次运行 xrandr：
Screen 0: minimum 8 x 8, current 4480 x 1440, maximum 32767 x 32767
eDP1 connected primary 1920x1080+0+360 (normal left inverted right x axis y axis) 309mm x 173mm
1920x1080 60.0*+ 59.9
1680x1050 60.0 59.9
1600x1024 60.2
1400x1050 60.0
1280x1024 60.0
1440x900 59.9
1280x960 60.0
1360x768 59.8 60.0
1152x864 60.0
1024x768 60.0
800x600 60.3 56.2
640x480 59.9
DP1 connected 2560x1440+1920+0 (normal left inverted right x axis y axis) 527mm x 296mm
3840x2160 60.0 +
2560x1440 60.0*
2048x1280 60.0
1920x1200 59.9
1920x1080 60.0 60.0 50.0 59.9 30.0 25.0 24.0 30.0 24.0
1920x1080i 60.1 50.0 60.0
1600x1200 60.0
1600x900 60.0
1280x1024 75.0 60.0
1152x864 75.0
1280x720 60.0 50.0 59.9
1024x768 75.1 60.0
800x600 75.0 60.3
720x576 50.0
720x480 60.0 59.9
640x480 75.0 60.0 59.9
720x400 70.1
3840x2160_30.00 30.0
DP2 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
不知道接下来该怎么办。这是硬件问题吗？我做错了什么吗？