Dedicated graphics card not showing as provider in xrandr

I am trying to get use the HDMI output on my laptop. It seems to be hardwired to my dedicated GPU. Unfortunately, the dedicated GPU does not show up as a provider under xrandr. This is the output of xrandr:

xrandr --listproviders
Providers: number : 1
Provider 0: id: 0x45 cap: 0xf, Source Output, Sink Output, Source Offload, Sink Offload crtcs: 3 outputs: 4 associated providers: 0 name:modesetting

My laptop is an Dell Precision M4800 with the following relevant hardware configuration:

Intel Core i7-4810MQ w/ HD Graphics 4600
AMD FirePro M5100

According to lspci, drivers for both cards are loaded:

❯ lspci -k | grep -A 3 -E "(VGA|3D)"
00:02.0 VGA compatible controller: Intel Corporation 4th Gen Core Processor Integrated Graphics Controller (rev 06)
	DeviceName:  Onboard IGD
	Subsystem: Dell Device 05cc
	Kernel driver in use: i915
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Venus XT [Radeon HD 8870M / R9 M270X/M370X]
	Subsystem: Dell FirePro M5100
	Kernel driver in use: radeon
	Kernel modules: radeon, amdgpu

If I understood RadeonFeature on xorg website (cannot post links, sorry) correct, radeon is the preferred driver for my dedicated GPU. Looking at the arch wiki on PRIME, installing the drivers should be enough for both providers to show up. It does not happen, though.I am a bit lost. Any hints how I could solve the problem are appreciated.