我有一台配备 2 个 AMD Radeon R5 230 显卡的电脑，其中一个配备了 2 个 1920x1080 屏幕（HTMI 和 DVI），另一个配备了 1 个 1920x1080 屏幕（HDMI）。
我将第一个显卡中的两个屏幕旋转为纵向模式，将第二个显卡上的屏幕旋转为横向模式。
我使用 Unity UI 工具（系统设置 -> 屏幕显示）配置了桌面，并根据需要设置了屏幕，但是当我将显卡 1 上的第二个屏幕设置为旋转时，两个纵向屏幕的分辨率都会降低约400像素。
查看 xrandr -q 我看到以下内容：
Screen 0: minimum 320 x 200, current 4920 x 1515, maximum 16384 x 16384
HDMI-0 connected 1080x1920+0+12 left (normal left inverted right x axis y axis) 531mm x 299mm
1920x1080 60.00*+ 50.00 59.94 24.00 23.98
1920x1080i 60.00 50.00 50.00 59.94
1600x1200 60.00
1680x1050 59.88
1600x900 60.00
1280x1024 75.02 60.02
1440x900 74.98 59.90
1280x960 60.00
1152x864 75.00
1280x720 60.00 50.00 59.94
1024x768 75.08 70.07 60.00
832x624 74.55
800x600 72.19 75.00 60.32 56.25
720x576 50.00
720x576i 50.00
720x480 60.00 59.94
720x480i 60.00 59.94
640x480 75.00 72.81 66.67 60.00 59.94
720x400 70.08
DVI-0 connected 1080x1920+3000+0 left (normal left inverted right x axis y axis) 531mm x 299mm
1920x1080 60.00*+ 144.00 119.98 109.95 99.93 59.94
1600x1200 60.00
1680x1050 59.88
1280x1024 120.00 100.00 75.02 60.02
1440x900 59.90
1280x960 60.00
1152x864 75.00
1024x768 119.99 99.97 75.08 70.07 60.00
832x624 74.55
800x600 72.19 75.00 60.32 56.25
640x480 75.00 72.81 66.67 60.00 59.94
720x400 70.08
VGA-0 disconnected (normal left inverted right x axis y axis)
HDMI-1-1 connected primary 1920x1080+1080+435 531mm x 299mm
1920x1080 60.00*+ 50.00 59.94 24.00 23.98
1920x1080i 60.00 50.00 50.00 59.94
1600x1200 60.00
1680x1050 59.88
1600x900 60.00
1280x1024 75.02 60.02
1440x900 74.98 59.90
1280x960 60.00
1152x864 75.00
1280x720 60.00 50.00 59.94
1024x768 75.08 70.07 60.00
832x624 74.55
800x600 72.19 75.00 60.32 56.25
720x576 50.00
720x576i 50.00
720x480 60.00 59.94
720x480i 60.00 59.94
640x480 75.00 72.81 66.67 60.00 59.94
720x400 70.08
DVI-1-1 disconnected
VGA-1-1 disconnected
从上面的输出中可以看出，尽管所有屏幕都设置为最高分辨率，但 Screen 0 的尺寸设置为 4920x1515，而不是 4920x1920。我一直在尝试更改屏幕尺寸但没有成功。我尝试过的：
preichert@2015-PC-19:~/.config$ cvt 4920 1920 60
# 4920x1920 59.97 Hz (CVT) hsync: 119.28 kHz; pclk: 808.25 MHz
Modeline "4920x1920_60.00" 808.25 4920 5312 5848 6776 1920 1923 1933 1989 -hsync +vsync
preichert@2015-PC-19:~/.config$ xrandr --newmode "4920x1920_60.00" 808.25 4920 5312 5848 6776 1920 1923 1933 1989 -hsync +vsync
preichert@2015-PC-19:~/.config$ xrandr --screen 0 --size 4920x1920
Size 4920x1920 not found in available modes
我还没有尝试创建自定义 xorg.conf 文件，因为我认为这是最后的手段，而且我不知道如何在其上配置我的两个显卡。这是它们的样子：
preichert@2015-PC-19:~/.config$ lspci
...
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Caicos [Radeon HD 6450/7450/8450 / R5 230 OEM]
01:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Caicos HDMI Audio [Radeon HD 6400 Series]
02:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Caicos [Radeon HD 6450/7450/8450 / R5 230 OEM]
02:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Caicos HDMI Audio [Radeon HD 6400 Series]
...
和：
preichert@2015-PC-19:/usr/share/X11/xorg.conf.d$ xrandr --listproviders
Providers: number : 3
Provider 0: id: 0xa6 cap: 0x9, Source Output, Sink Offload crtcs: 4 outputs: 3 associated providers: 2 name:radeon
Provider 1: id: 0x46 cap: 0x6, Sink Output, Source Offload crtcs: 4 outputs: 3 associated providers: 2 name:radeon
Provider 2: id: 0x46 cap: 0x6, Sink Output, Source Offload crtcs: 4 outputs: 3 associated providers: 2 name:radeon
答案1
sudo xrandr --addmode VGA-1 4920x1920_60.00