[PATCH] Disable panel self-refresh on AMD GPUs

[PATCH] Disable panel self-refresh on AMD GPUs

[Demi Marie Obenour]

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.

Signed-off-by: Demi Marie Obenour <demiobenour@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)

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

[Demi Marie Obenour]

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)

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

[Alyssa Ross]

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Demi Marie Obenour <demiobenour@gmail.com> writes:

> 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.

You tested this on your test laptop and it solved the problem?  Did you
manually work around the card0/card1 bug?  Do the proposed upstream
patches also solve the problem?

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

[Demi Marie Obenour]

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On 5/21/26 08:52, Alyssa Ross wrote:
> Demi Marie Obenour <demiobenour@gmail.com> writes:
> 
>> 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.
> 
> You tested this on your test laptop and it solved the problem?

I didn't test it on my own hardware.  After having spent so long on
Cloud Hypervisor, I'm having to set myself up for Spectrum development
again, and that is taking a little bit of time.

However, the symptoms are identical to what many others have seen:
a freeze that needs a hard reboot to recover from.

> Did you manually work around the card0/card1 bug?

That bug would cause Weston to fail to start, but not to freeze
once started.

> Do the proposed upstream patches also solve the problem?

I do not know, but they aren't in any stable kernel release yet, and
KDE decided they weren't willing to wait for them.  I don't think it
makes sense for Spectrum to wait, either.

The bug breaks Spectrum on what I suspect is a significant amount
of hardware.  Panel self-refresh is a completely optional feature
that only saves a small amount of power.

I'm inclined to trust the KWin developers' judgement on this.
If KDE Linux reverts this change, I will send a patch to revert it
in Spectrum.
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)

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

[Alyssa Ross]

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Demi Marie Obenour <demiobenour@gmail.com> writes:

> On 5/21/26 08:52, Alyssa Ross wrote:
>> Demi Marie Obenour <demiobenour@gmail.com> writes:
>> 
>>> 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.
>> 
>> You tested this on your test laptop and it solved the problem?
>
> I didn't test it on my own hardware.  After having spent so long on
> Cloud Hypervisor, I'm having to set myself up for Spectrum development
> again, and that is taking a little bit of time.
>
> However, the symptoms are identical to what many others have seen:
> a freeze that needs a hard reboot to recover from.
>
>> Did you manually work around the card0/card1 bug?
>
> That bug would cause Weston to fail to start, but not to freeze
> once started.

Right, but you'd have to get past it to even observe this problem,
wouldn't you?  So I'm not sure anybody would actually be affected by
this currently.

>> Do the proposed upstream patches also solve the problem?
>
> I do not know, but they aren't in any stable kernel release yet, and
> KDE decided they weren't willing to wait for them.  I don't think it
> makes sense for Spectrum to wait, either.
>
> The bug breaks Spectrum on what I suspect is a significant amount
> of hardware.  Panel self-refresh is a completely optional feature
> that only saves a small amount of power.
>
> I'm inclined to trust the KWin developers' judgement on this.
> If KDE Linux reverts this change, I will send a patch to revert it
> in Spectrum.
> -- 
> Sincerely,
> Demi Marie Obenour (she/her/hers)

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