From 5e088af7edc8806359e1cbfd89fa23f839245d3d Mon Sep 17 00:00:00 2001
From: enricobuehler <buehler@unom.io>
Date: Wed, 22 Jul 2026 12:26:44 +0200
Subject: [PATCH] fix(pf-win-display): unpin mode indexes on paths the CCD
 isolate deactivates
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Field report: with Exclusive Topology, the physical monitor sometimes stayed
lit — every isolate attempt re-committed and failed SetDisplayConfig with
0x57 ERROR_INVALID_PARAMETER. Clearing DISPLAYCONFIG_PATH_ACTIVE alone leaves
the deactivated path's source/target modeInfoIdx pinned to the queried mode
entries, and per the SetDisplayConfig contract a path being turned off must
have BOTH mode indexes set to DISPLAYCONFIG_PATH_MODE_IDX_INVALID; some
driver/topology combinations (notably when the doomed path shares a source
with the kept virtual path) reject the supplied config outright, so the
retry loop could never converge.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 crates/pf-win-display/src/win_display.rs | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/crates/pf-win-display/src/win_display.rs b/crates/pf-win-display/src/win_display.rs
index 39b44174..ffaf610b 100644
--- a/crates/pf-win-display/src/win_display.rs
+++ b/crates/pf-win-display/src/win_display.rs
@@ -861,7 +861,18 @@ pub unsafe fn isolate_displays_ccd(keep_target_ids: &[u32]) -> Option<SavedConfi
                 continue;
             }
             if p.flags & DISPLAYCONFIG_PATH_ACTIVE != 0 {
-                p.flags &= !DISPLAYCONFIG_PATH_ACTIVE; // mark this path inactive
+                // Mark the path inactive AND unpin its modes: per the SetDisplayConfig
+                // contract a path being turned OFF needs BOTH mode indexes marked invalid,
+                // and leaving them referencing the queried mode entries gets the whole
+                // supplied config rejected with 0x57 ERROR_INVALID_PARAMETER on some
+                // driver/topology combinations (field-reported: exclusive mode left the
+                // physical panel lit, every retry failing 0x57). Writing the all-ones
+                // sentinel to the whole union is also correct under the virtual-mode-aware
+                // interpretation (cloneGroupId/sourceModeInfoIdx both become their 0xffff
+                // INVALID values).
+                p.flags &= !DISPLAYCONFIG_PATH_ACTIVE;
+                p.sourceInfo.Anonymous.modeInfoIdx = DISPLAYCONFIG_PATH_MODE_IDX_INVALID;
+                p.targetInfo.Anonymous.modeInfoIdx = DISPLAYCONFIG_PATH_MODE_IDX_INVALID;
                 others += 1;
             }
         }