Fedora and Windows screen resolutions don’t match on a PBP monitor

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1

While I’ve posted a similar topic, I have since learned a little bit about EDID.

I use a single monitor in PBP mode with Fedora and Windows machines.

Before F43, both sides had resolutions of 1920x2160 (the full screen being 3840x2160).

After F43, the Windows side is still 1920x2160, but the Fedora side has shrunk to 1920x1080.

I grabbed the EDID info from the Windows Registry and from /sys/class/drm both as full- and half-screen.

The EDID info for half (1920) and full (3840) screens are identical between systems for the two half screens, but differ in the full screen specs – I expected both to be the same, or to differ only on the half-width screens, where the problem occurs.

Given the EDID info below, it would seem that I should get 1920x2160 under Fedora just as I do under Windows, since the half-screen Fedora EDID does have a 1920x2160 line.

What am I missing?

Thanks!

Half-screen and split-screen excerpts from Windows:

HALF SCREEN
$ cat win_half_edid.bin | edid-decode | grep -n "\(3840\|1920\)x"
66:    DTD 1:  1920x2160   59.987970 Hz   8:9    133.293 kHz    277.250000 MHz (607 mm x 345 mm)
69:    DTD 2:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (607 mm x 345 mm)
88:    VIC  16:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (native)
90:    VIC  31:  1920x1080   50.000000 Hz  16:9     56.250 kHz    148.500000 MHz
94:    VIC  32:  1920x1080   24.000000 Hz  16:9     27.000 kHz     74.250000 MHz
95:    VIC  34:  1920x1080   30.000000 Hz  16:9     33.750 kHz     74.250000 MHz
107:    DTD 3:  1920x1080   50.000000 Hz  16:9     56.250 kHz    148.500000 MHz (607 mm x 345 mm)

$ edid-decode < /sys/class/drm/card1-HDMI-A-5/edid | grep -n "\(3840\|1920\)x"
66:    DTD 1:  1920x2160   59.987970 Hz   8:9    133.293 kHz    277.250000 MHz (607 mm x 345 mm)
69:    DTD 2:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (607 mm x 345 mm)
88:    VIC  16:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (native)
90:    VIC  31:  1920x1080   50.000000 Hz  16:9     56.250 kHz    148.500000 MHz
94:    VIC  32:  1920x1080   24.000000 Hz  16:9     27.000 kHz     74.250000 MHz
95:    VIC  34:  1920x1080   30.000000 Hz  16:9     33.750 kHz     74.250000 MHz
107:    DTD 3:  1920x1080   50.000000 Hz  16:9     56.250 kHz    148.500000 MHz (607 mm x 345 mm)

FULL SCREEN
$ cat win_full_edid.bin | edid-decode | grep -n "\(3840\|1920\)x"
67:    DTD 1:  3840x2160   30.000000 Hz  16:9     67.500 kHz    297.000000 MHz (608 mm x 345 mm)
87:    VIC  95:  3840x2160   30.000000 Hz  16:9     67.500 kHz    297.000000 MHz
88:    VIC  16:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz
90:    VIC  31:  1920x1080   50.000000 Hz  16:9     56.250 kHz    148.500000 MHz
94:    VIC  32:  1920x1080   24.000000 Hz  16:9     27.000 kHz     74.250000 MHz
95:    VIC  34:  1920x1080   30.000000 Hz  16:9     33.750 kHz     74.250000 MHz
110:        HDMI VIC 1:  3840x2160   30.000000 Hz  16:9     67.500 kHz    297.000000 MHz
111:        HDMI VIC 2:  3840x2160   25.000000 Hz  16:9     56.250 kHz    297.000000 MHz
112:        HDMI VIC 3:  3840x2160   24.000000 Hz  16:9     54.000 kHz    297.000000 MHz
114:    DTD 2:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (608 mm x 345 mm)
117:    DTD 3:  1920x1080   50.000000 Hz  16:9     56.250 kHz    148.500000 MHz (608 mm x 345 mm)

$ edid-decode < /sys/class/drm/card1-HDMI-A-5/edid | grep -n "\(3840\|1920\)x"
67:    DTD 1:  3840x2160   60.000000 Hz  16:9    135.000 kHz    594.000000 MHz (608 mm x 345 mm)
87:    VIC  97:  3840x2160   60.000000 Hz  16:9    135.000 kHz    594.000000 MHz
92:    VIC  32:  1920x1080   24.000000 Hz  16:9     27.000 kHz     74.250000 MHz
93:    VIC  34:  1920x1080   30.000000 Hz  16:9     33.750 kHz     74.250000 MHz
94:    VIC  31:  1920x1080   50.000000 Hz  16:9     56.250 kHz    148.500000 MHz
95:    VIC  16:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz
96:    VIC  95:  3840x2160   30.000000 Hz  16:9     67.500 kHz    297.000000 MHz
97:    VIC  96:  3840x2160   50.000000 Hz  16:9    112.500 kHz    594.000000 MHz
98:    VIC  93:  3840x2160   24.000000 Hz  16:9     54.000 kHz    297.000000 MHz
99:    VIC  94:  3840x2160   25.000000 Hz  16:9     56.250 kHz    297.000000 MHz
114:        HDMI VIC 1:  3840x2160   30.000000 Hz  16:9     67.500 kHz    297.000000 MHz
115:        HDMI VIC 2:  3840x2160   25.000000 Hz  16:9     56.250 kHz    297.000000 MHz
116:        HDMI VIC 3:  3840x2160   24.000000 Hz  16:9     54.000 kHz    297.000000 MHz
124:    VIC  97:  3840x2160   60.000000 Hz  16:9    135.000 kHz    594.000000 MHz
125:    VIC  96:  3840x2160   50.000000 Hz  16:9    112.500 kHz    594.000000 MHz
127:    DTD 2:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (608 mm x 345 mm)
130:    DTD 3:  1920x1080   50.000000 Hz  16:9     56.250 kHz    148.500000 MHz (608 mm x 345 mm)
3

Thanks.

I guess I could try that – which of the two different EDIDs from the WIndows PC should I use?

I don’t know much about the EDID spec. Being naïve, I assumed that every monitor would have only one EDID – not a different EDID for every possible resolution.

What am I missing?