pc_intel_fb_drv: driver hang at boot time

[a-dmg]

Dear Genodians,

While testing sculpt-24.04 on my Razer Blade 15, Sculpt would be stuck on the Genode logo at boot time. After some investigation, the pc_intel_fb_drv hangs very early during initialization, resulting in no framebuffer available.

This computer possesses an Intel i7 8th generation with an integrated GPU and a supplementary Nvidia discreet GPU.

During startup, the following devices are listed in the platform session of the intel_gpu_drv:

<devices>
	<device name="00:02.0" type="pci" used="true">
		<io_mem pci_bar="0" phys_addr="0xab000000" size="0x1000000"/>
		<io_mem pci_bar="2" phys_addr="0x40000000" size="0x10000000"/>
		<irq number="4"/>
		<io_port_range pci_bar="4" phys_addr="0x5000" size="0x40"/>
		<pci-config vendor_id="0x8086" device_id="0x3e9b" class="0x30000" revision="0x0" sub_vendor_id="0x1a58" sub_device_id="0x2001" intel_gmch_control="0x1c1"/>
	</device>
	<device name="00:1f.0" type="pci" used="false">
		<pci-config vendor_id="0x8086" device_id="0xa30d" class="0x60100" revision="0x10" sub_vendor_id="0xffff" sub_device_id="0xffff"/>
	</device>
	<device name="01:00.0" type="pci" used="false">
		<io_mem pci_bar="0" phys_addr="0xac000000" size="0x1000000"/>
		<io_mem pci_bar="1" phys_addr="0x80000000" size="0x10000000"/>
		<io_mem pci_bar="3" phys_addr="0x90000000" size="0x2000000"/>
		<irq number="14"/>
		<io_port_range pci_bar="5" phys_addr="0x4000" size="0x80"/>
		<pci-config vendor_id="0x10de" device_id="0x1c20" class="0x30000" revision="0xa1" sub_vendor_id="0x1a58" sub_device_id="0x2001"/>
	</device>
</devices>

You can notice the two Intel devices with vendor ID 0x8086 are expected. And one extra Nvidia device with vendor ID 0x10de. This extra device is due to the configuration of the platform driver, which handouts any devices of class VGA to the intel_gpu_drv.

<policy label_prefix="runtime -> intel_gpu" info="yes">
    <pci class="VGA"/>
    <pci class="ISABRIDGE"/>
</policy>

The driver will hang until the Nvidia GPU is ready, which never happens as this device is not operated by the intel_gpu_drv following Issue #5180 commit 53230d3 @alex-ab.

Please find attached a commit that addresses this issue by enforcing the delay only on devices with Intel's vendor ID 0x8086.