[PATCH v2] Disable panel self-refresh on AMD GPUs

[Demi Marie Obenour <demiobenour@gmail.com>]

KDE Linux has already done this.  It works around a long-running bug in
the AMD GPU driver, which I believe also affects my test laptop.
Without the workaround, the system freezes and does not recover until a
hard reboot.

A potential fix has been sent upstream, but there's no guarantee it
fixes the problem and it isn't in mainline yet.  Once the relevant
the fix included in the latest stable kernel and confirmed to work,
this patch can be reverted.

Link: https://invent.kde.org/kde-linux/kde-linux/-/merge_requests/431
Link: https://gitlab.freedesktop.org/drm/amd/-/work_items/4831
Link: https://gitlab.freedesktop.org/drm/amd/-/work_items/4643
Link: https://gitlab.freedesktop.org/drm/amd/-/work_items/4816
Link: https://lore.kernel.org/amd-gfx/20260519220529.202096-1-sunpeng.li@amd.com/
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
---
Changes in v2:
- Link to multiple reports of the bug.
- Link to KDE Linux's choice to add amdgpu.dcdebugmask=0x10.
- Link to v1: https://spectrum-os.org/lists/archives/spectrum-devel/20260520-disable-panel-self-refresh-v1-1-dbc6ff6617c8@gmail.com
---
 host/efi.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/host/efi.nix b/host/efi.nix
index ecedb6bea6bf29c7a7303dc9062fe12b5c7a9fbd..a832489f3816ca66c2170f0f114a4a8e3a357e32 100644
--- a/host/efi.nix
+++ b/host/efi.nix
@@ -35,6 +35,6 @@ runCommand "spectrum-efi" {
       --linux ${kernel} \
       --initrd ${initramfs} \
       --os-release $'NAME="Spectrum"\n' \
-      --cmdline "ro intel_iommu=on roothash=$roothash"
+      --cmdline "ro intel_iommu=on roothash=$roothash amdgpu.dcdebugmask=0x10"
   ''
 ) (_: {})

---
base-commit: 5b3151fd08d1f1e3e166a328449fe6fe5092f316
change-id: 20260520-disable-panel-self-refresh-6c5e1dc0bab5

-- 
Sincerely,
Demi Marie Obenour (she/her/hers)