From 8af4c8abfb59ab66f1f5a34f0eac1342e6f0c7e5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
Date: Thu, 17 Oct 2019 12:37:12 +0200
Subject: [PATCH] udev: tag any display devices as master-of-seat when
 nomodeset is used
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Fixes #13773. See also https://bugzilla.redhat.com/show_bug.cgi?id=1728240,
https://github.com/sddm/sddm/issues/1204.

When nomodeset is used on the kernel command line, there is no graphics
device that the kernel knows, so we don't tag anything as master-of-seat,
and seat0 has CanGraphical=no.

$ loginctl seat-status seat0 ; loginctl show-seat seat0
seat0
         Devices:
                  ├─/sys/devices/LNXSYSTM:00/LNXPWRBN:00/input/input0
                  │ input:input0 "Power Button"
                  ├─/sys/devices/pci0000:00/0000:00:02.1/0000:02:00.0/usb1
                  │ usb:usb1
                  │ └─/sys/devices/pci0000:00/0000:00:02.1/0000:02:00.0/usb1/1-1/1-1:1.0/0003:0627:0001.0001/input/input4
                  │   input:input4 "QEMU QEMU USB Tablet"
                  ├─/sys/devices/pci0000:00/0000:00:02.1/0000:02:00.0/usb2
                  │ usb:usb2
                  ├─/sys/devices/pci0000:00/0000:00:1b.0/sound/card0
                  │ sound:card0 "Intel"
                  ├─/sys/devices/platform/i8042/serio0/input/input1
                  │ input:input1 "AT Translated Set 2 keyboard"
                  │ ├─/sys/devices/platform/i8042/serio0/input/input1/input1::capslock
                  │ │ leds:input1::capslock
                  │ ├─/sys/devices/platform/i8042/serio0/input/input1/input1::numlock
                  │ │ leds:input1::numlock
                  │ └─/sys/devices/platform/i8042/serio0/input/input1/input1::scrolllock
                  │   leds:input1::scrolllock
                  └─/sys/devices/platform/i8042/serio1/input/input3
                    input:input3 "ImExPS/2 Generic Explorer Mouse"
Id=seat0
CanMultiSession=yes
CanTTY=yes
CanGraphical=no
Sessions=
IdleHint=yes
IdleSinceHint=0
IdleSinceHintMonotonic=0

Let's tag the PCI device with "master-of-seat", so we get CanGraphical=yes, and "seat",
so it is show as part of the seat:

[fedora@f31-bios ~]$ loginctl seat-status seat0 ; loginctl show-seat seat0
seat0
         Devices:
                  ├─/sys/devices/LNXSYSTM:00/LNXPWRBN:00/input/input0
                  │ input:input0 "Power Button"
                  ├─/sys/devices/pci0000:00/0000:00:01.0
                  │ [MASTER] pci:0000:00:01.0
                  ├─/sys/devices/pci0000:00/0000:00:02.1/0000:02:00.0/usb1
                  │ usb:usb1
                  │ └─/sys/devices/pci0000:00/0000:00:02.1/0000:02:00.0/usb1/1-1/1-1:1.0/0003:0627:0001.0001/input/input4
                  │   input:input4 "QEMU QEMU USB Tablet"
                  ├─/sys/devices/pci0000:00/0000:00:02.1/0000:02:00.0/usb2
                  │ usb:usb2
                  ├─/sys/devices/pci0000:00/0000:00:1b.0/sound/card0
                  │ sound:card0 "Intel"
                  ├─/sys/devices/platform/i8042/serio0/input/input1
                  │ input:input1 "AT Translated Set 2 keyboard"
                  │ ├─/sys/devices/platform/i8042/serio0/input/input1/input1::capslock
                  │ │ leds:input1::capslock
                  │ ├─/sys/devices/platform/i8042/serio0/input/input1/input1::numlock
                  │ │ leds:input1::numlock
                  │ └─/sys/devices/platform/i8042/serio0/input/input1/input1::scrolllock
                  │   leds:input1::scrolllock
                  └─/sys/devices/platform/i8042/serio1/input/input3
                    input:input3 "ImExPS/2 Generic Explorer Mouse"
Id=seat0
CanMultiSession=yes
CanTTY=yes
CanGraphical=yes
Sessions=
IdleHint=yes
IdleSinceHint=0
IdleSinceHintMonotonic=0
---
 src/login/71-seat.rules.in | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/login/71-seat.rules.in b/src/login/71-seat.rules.in
index 6010f048aef..2bbd18363e6 100644
--- a/src/login/71-seat.rules.in
+++ b/src/login/71-seat.rules.in
@@ -24,6 +24,11 @@ SUBSYSTEM=="graphics", KERNEL=="fb[0-9]", DRIVERS=="hyperv_fb", TAG+="master-of-
 # Allow efifb / uvesafb to be a master if KMS is disabled
 SUBSYSTEM=="graphics", KERNEL=="fb[0-9]", IMPORT{cmdline}="nomodeset", TAG+="master-of-seat"
 
+# Allow any PCI graphics device to be a master and synthesize a seat if KMS
+# is disabled and the kernel doesn't have a driver that would work with this device.
+SUBSYSTEM=="pci", ENV{ID_PCI_CLASS_FROM_DATABASE}=="Display controller", \
+                  ENV{DRIVER}=="", IMPORT{cmdline}="nomodeset", TAG+="seat", TAG+="master-of-seat"
+
 SUBSYSTEM=="drm", KERNEL=="card[0-9]*", TAG+="seat", TAG+="master-of-seat"
 SUBSYSTEM=="usb", ATTR{bDeviceClass}=="09", TAG+="seat"