Comment 130 for bug 1958191

Adding the kernel parameters to the grub configuration greatly reduces the flicker on my Dell Precision 5480 running Ubuntu 22.04. However, it returns every few seconds after the external display has gone to standby, despite /sys/module/i915/parameters/enable_dc and /sys/module/intel_idle/parameters/max_cstate still reporting their updated values.

0000:00:02.0 VGA compatible controller: Intel Corporation Device a7a0 (rev 04) (prog-if 00 [VGA controller])
 Subsystem: Dell Device 0c40
 Flags: bus master, fast devsel, latency 0, IRQ 213, IOMMU group 1
 Memory at 607f000000 (64-bit, non-prefetchable) [size=16M]
 Memory at 4000000000 (64-bit, prefetchable) [size=256M]
 I/O ports at 3000 [size=64]
 Expansion ROM at 000c0000 [virtual] [disabled] [size=128K]
 Capabilities: [40] Vendor Specific Information: Len=0c <?>
 Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00
 Capabilities: [ac] MSI: Enable+ Count=1/1 Maskable+ 64bit-
 Capabilities: [d0] Power Management version 2
 Capabilities: [100] Process Address Space ID (PASID)
 Capabilities: [200] Address Translation Service (ATS)
 Capabilities: [300] Page Request Interface (PRI)
 Capabilities: [320] Single Root I/O Virtualization (SR-IOV)
 Kernel driver in use: i915
 Kernel modules: i915