From eff728fdf5f090663ebcc7e5f5bd49e91f676591 Mon Sep 17 00:00:00 2001
From: DavutHaxor <37223772+DavutHaxor@users.noreply.github.com>
Date: Tue, 14 Apr 2026 17:27:36 +0300
Subject: [PATCH] Fix ddc brightness not applying because process exits before
 debounce timer runs (#2217)

* Fix ddc brightness not applying because process exits before debounce timer runs

* Added sync.WaitGroup to DDCBackend and use it instead of loop in wait logic, added timeout in case i2c hangs.

* go fmt

---------

Co-authored-by: bbedward <bbedward@gmail.com>
---
 core/cmd/dms/commands_brightness.go      |  1 +
 core/internal/server/brightness/ddc.go   | 16 ++++++++++++++++
 core/internal/server/brightness/types.go |  1 +
 3 files changed, 18 insertions(+)

diff --git a/core/cmd/dms/commands_brightness.go b/core/cmd/dms/commands_brightness.go
index 8e7aafd5..0f734937 100644
--- a/core/cmd/dms/commands_brightness.go
+++ b/core/cmd/dms/commands_brightness.go
@@ -236,6 +236,7 @@ func runBrightnessSet(cmd *cobra.Command, args []string) {
 			defer ddc.Close()
 			time.Sleep(100 * time.Millisecond)
 			if err := ddc.SetBrightnessWithExponent(deviceID, percent, exponential, exponent, nil); err == nil {
+				ddc.WaitPending()
 				fmt.Printf("Set %s to %d%%\n", deviceID, percent)
 				return
 			}
diff --git a/core/internal/server/brightness/ddc.go b/core/internal/server/brightness/ddc.go
index a5e4802d..00cf2d9a 100644
--- a/core/internal/server/brightness/ddc.go
+++ b/core/internal/server/brightness/ddc.go
@@ -218,7 +218,9 @@ func (b *DDCBackend) SetBrightnessWithExponent(id string, value int, exponential
 	if timer, exists := b.debounceTimers[id]; exists {
 		timer.Reset(200 * time.Millisecond)
 	} else {
+		b.debounceWg.Add(1)
 		b.debounceTimers[id] = time.AfterFunc(200*time.Millisecond, func() {
+			defer b.debounceWg.Done()
 			b.debounceMutex.Lock()
 			pending, exists := b.debouncePending[id]
 			if exists {
@@ -490,5 +492,19 @@ func (b *DDCBackend) valueToPercent(value int, max int, exponential bool) int {
 	return percent
 }
 
+func (b *DDCBackend) WaitPending() {
+	done := make(chan struct{})
+	go func() {
+		b.debounceWg.Wait()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+	case <-time.After(5 * time.Second):
+		log.Debug("WaitPending timed out waiting for DDC writes")
+	}
+}
+
 func (b *DDCBackend) Close() {
 }
diff --git a/core/internal/server/brightness/types.go b/core/internal/server/brightness/types.go
index 0db7f7a6..81e00cfe 100644
--- a/core/internal/server/brightness/types.go
+++ b/core/internal/server/brightness/types.go
@@ -84,6 +84,7 @@ type DDCBackend struct {
 	debounceMutex   sync.Mutex
 	debounceTimers  map[string]*time.Timer
 	debouncePending map[string]ddcPendingSet
+	debounceWg      sync.WaitGroup
 }
 
 type ddcPendingSet struct {