From a3237b741c9e5c2eace66f7bf56f909611426f5a Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Tue, 6 Jan 2026 01:59:20 -0600
Subject: [PATCH] Support underlay planes by turning off unused active planes

---
 app/streaming/video/ffmpeg-renderers/drm.cpp | 32 +++++++++++++++++---
 app/streaming/video/ffmpeg-renderers/drm.h   | 16 ++++++++++
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/app/streaming/video/ffmpeg-renderers/drm.cpp b/app/streaming/video/ffmpeg-renderers/drm.cpp
index ed1c0763..6d2e12f5 100644
--- a/app/streaming/video/ffmpeg-renderers/drm.cpp
+++ b/app/streaming/video/ffmpeg-renderers/drm.cpp
@@ -191,6 +191,12 @@ DrmRenderer::~DrmRenderer()
                 m_PropSetter.set(*zpos, zpos->initialValue());
             }
         }
+        for (auto &plane : m_UnusedActivePlanes) {
+            SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+                        "Restoring previously active plane: %u",
+                        plane.second.objectId());
+            m_PropSetter.restoreToInitial(plane.second);
+        }
 
         m_PropSetter.apply();
     }
@@ -392,6 +398,14 @@ void DrmRenderer::prepareToRender()
         }
     }
 
+    // Disable all other active planes in atomic mode
+    for (auto &plane : m_UnusedActivePlanes) {
+        SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+                    "Disabling unused plane: %u",
+                    plane.second.objectId());
+        m_PropSetter.disablePlane(plane.second);
+    }
+
     m_PropSetter.apply();
 
     // We've now changed state that must be restored
@@ -598,22 +612,28 @@ bool DrmRenderer::initialize(PDECODER_PARAMETERS params)
     }
 
     // Find the active plane (if any) on this CRTC with the highest zpos.
-    // We'll need to use a plane with a equal or greater zpos to be visible.
+    // We'll need to use a plane with a equal or greater zpos to be visible,
+    // or we'll disable the active planes if we're in atomic mode.
     std::set<uint64_t> activePlanesZpos;
     for (uint32_t i = 0; i < planeRes->count_planes; i++) {
         drmModePlane* plane = drmModeGetPlane(m_DrmFd, planeRes->planes[i]);
         if (plane != nullptr) {
+            DrmPropertyMap props { m_DrmFd, planeRes->planes[i], DRM_MODE_OBJECT_PLANE };
+
             if (plane->crtc_id == m_Crtc.objectId()) {
                 // Don't consider cursor planes when searching for the highest active zpos
-                DrmPropertyMap props { m_DrmFd, planeRes->planes[i], DRM_MODE_OBJECT_PLANE };
-                if (props.property("type")->initialValue() == DRM_PLANE_TYPE_PRIMARY ||
-                    props.property("type")->initialValue() == DRM_PLANE_TYPE_OVERLAY) {
+                uint64_t type = props.property("type")->initialValue();
+                if (type == DRM_PLANE_TYPE_PRIMARY || type == DRM_PLANE_TYPE_OVERLAY) {
                     SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
                                 "Plane %u is active on CRTC %u",
                                 plane->plane_id,
                                 plane->crtc_id);
 
-                    if (auto zpos = props.property("zpos")) {
+                    // We can only restore state of planes on atomic
+                    if (m_PropSetter.isAtomic()) {
+                        m_UnusedActivePlanes.try_emplace(planeRes->planes[i], m_DrmFd, planeRes->planes[i], DRM_MODE_OBJECT_PLANE);
+                    }
+                    else if (auto zpos = props.property("zpos")) {
                         activePlanesZpos.emplace(zpos->initialValue());
                     }
                 }
@@ -752,6 +772,7 @@ bool DrmRenderer::initialize(PDECODER_PARAMETERS params)
             SDL_assert(!m_VideoPlane.isValid());
             m_VideoPlane.load(m_DrmFd, plane->plane_id, DRM_MODE_OBJECT_PLANE);
             SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Selected plane %u for video", plane->plane_id);
+            m_UnusedActivePlanes.erase(plane->plane_id);
             drmModeFreePlane(plane);
         }
     }
@@ -831,6 +852,7 @@ bool DrmRenderer::initialize(PDECODER_PARAMETERS params)
             m_OverlayPlanes[overlayIndex++].load(m_DrmFd, plane->plane_id, DRM_MODE_OBJECT_PLANE);
             SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Selected plane %u for overlay %d",
                         plane->plane_id, overlayIndex);
+            m_UnusedActivePlanes.erase(plane->plane_id);
             drmModeFreePlane(plane);
         }
     }
diff --git a/app/streaming/video/ffmpeg-renderers/drm.h b/app/streaming/video/ffmpeg-renderers/drm.h
index d33f0969..43a3547b 100644
--- a/app/streaming/video/ffmpeg-renderers/drm.h
+++ b/app/streaming/video/ffmpeg-renderers/drm.h
@@ -189,6 +189,10 @@ class DrmRenderer : public IFFmpegRenderer {
             return m_ObjectType;
         }
 
+        const std::unordered_map<std::string, DrmProperty>& properties() const {
+            return m_Props;
+        }
+
     private:
         uint32_t m_ObjectId = 0;
         uint32_t m_ObjectType = 0;
@@ -605,6 +609,17 @@ class DrmRenderer : public IFFmpegRenderer {
             return m_Atomic;
         }
 
+        void restoreToInitial(const DrmPropertyMap& object) {
+            SDL_assert(m_Atomic);
+
+            // Set all mutable properties back to their initial values
+            for (auto& prop : object.properties()) {
+                if (!prop.second.isImmutable()) {
+                    set(prop.second, prop.second.initialValue());
+                }
+            }
+        }
+
     private:
         int m_Fd = -1;
         bool m_Atomic = false;
@@ -668,6 +683,7 @@ private:
     DrmPropertyMap m_Encoder;
     DrmPropertyMap m_Connector;
     DrmPropertyMap m_Crtc;
+    std::unordered_map<uint32_t, DrmPropertyMap> m_UnusedActivePlanes;
     DrmPropertyMap m_VideoPlane;
     uint64_t m_VideoPlaneZpos;
     DrmPropertyMap m_OverlayPlanes[Overlay::OverlayMax];