xf86platformProbeDev didn't check the device path, fix it.
This is a problem when trying to set up a non-PCI device via
explicit xorg.conf.d configuration.
An USB DisplayLink device, being non-PCI was always set up
as a GPU device assigned to screen 0 instead of a regular
framebuffer, potentially having its own dedicated screen,
despite such configuration as below. Only the relevant parts
of the configuration are quoted, it's part of a larger context
with an Intel chip that has 3 outputs:
* DP1 connected to an LCD panel,
* VGA1 connected to an external monitor,
* HDMI1 unconnected and having no user visible connector
Section "ServerFlags"
Option "AutoBindGPU" "false"
EndSection
...
Section "Device"
Identifier "Intel2"
Driver "intel"
BusID "PCI:0:2:0"
Screen 2
Option "Monitor-HDMI1" "HDMI1"
Option "ZaphodHeads" "HDMI1"
EndSection
Section "Device"
Identifier "UDL"
Driver "modesetting"
Option "kmsdev" "/dev/dri/card0"
#BusID "usb:0:1.2:1.0"
Option "Monitor-DVI-I-1" "DVI-I-1"
Option "ShadowFB" "on"
Option "DoubleShadow" "on"
EndSection
...
Section "Screen"
Identifier "SCREEN2"
Option "AutoServerLayout" "on"
Device "UDL"
GPUDevice "Intel2"
Monitor "Monitor-DVI-I-1"
SubSection "Display"
Modes "1024x768"
Depth 24
EndSubSection
EndSection
Section "ServerLayout"
Identifier "LAYOUT"
Option "AutoServerLayout" "on"
Screen 0 "SCREEN"
Screen 1 "SCREEN1" RightOf "SCREEN"
Screen 2 "SCREEN2" RightOf "SCREEN1"
EndSection
On the particular machine I was trying to set up an UDL device,
I found the following structure was being used to match
the device to a platform device while I was debugging the issue:
xf86_platform_devices[0] == Intel, /dev/dri/card1, primary platform device
xf86_platform_devices[1] == UDL, /dev/dri/card0
devList[0] == "Intel0", ZaphodHeads: DP1
devList[1] == "Intel1", ZaphodHeads: VGA1
devList[2] == "UDL"
devList[3] == "Intel2", ZaphodHeads: HDMI1 (intended GPU device to UDL)
When xf86platformProbeDev() matched the UDL device, the BusID
check failed in both cases of:
* BusID "usb:0:1.2:1.0" was specified
* Option "kmsdev" "/dev/dri/card0" was specified
As a result, xf86platformProbeDev() went on to call probeSingleDevice()
with xf86_platform_devices[0] and devList[2], resulting in the
UDL device being set up as a GPU device assigned to the first screen
instead of as a framebuffer on the third screen as the configuration
specified.
Checking Option "kmsdev" in code code may be a layering violation.
But the modesetting driver is actually part of the Xorg sources
instead of being an external driver, so he "kmsdev" path knowledge
may be used here.
Signed-off-by: Böszörményi Zoltán <zboszor@pr.hu>
42aaf37241