From cd4c1e920e846533c07304039a4e269e4cf066c4 Mon Sep 17 00:00:00 2001
From: refractionpcsx2 <refraction@gmail.com>
Date: Sat, 18 Feb 2023 20:09:22 +0000
Subject: [PATCH] GS: Flush targets back to GS memory when swapping renderers

---
 pcsx2/GS/GS.cpp                          | 2 ++
 pcsx2/GS/Renderers/HW/GSRendererHW.cpp   | 2 +-
 pcsx2/GS/Renderers/HW/GSTextureCache.cpp | 6 +++++-
 pcsx2/GS/Renderers/HW/GSTextureCache.h   | 2 +-
 4 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/pcsx2/GS/GS.cpp b/pcsx2/GS/GS.cpp
index 439beb40be..059b2dfa25 100644
--- a/pcsx2/GS/GS.cpp
+++ b/pcsx2/GS/GS.cpp
@@ -800,6 +800,8 @@ void GSSwitchRenderer(GSRendererType new_renderer)
 	if (existing_api == RenderAPI::OpenGLES)
 		existing_api = RenderAPI::OpenGL;
 
+	g_gs_renderer->PurgeTextureCache();
+
 	const bool is_software_switch = (new_renderer == GSRendererType::SW || GSConfig.Renderer == GSRendererType::SW);
 	const bool recreate_display = (!is_software_switch && existing_api != GetAPIForRenderer(new_renderer));
 	const Pcsx2Config::GSOptions old_config(GSConfig);
diff --git a/pcsx2/GS/Renderers/HW/GSRendererHW.cpp b/pcsx2/GS/Renderers/HW/GSRendererHW.cpp
index 193e875b01..ecb10ad774 100644
--- a/pcsx2/GS/Renderers/HW/GSRendererHW.cpp
+++ b/pcsx2/GS/Renderers/HW/GSRendererHW.cpp
@@ -72,7 +72,7 @@ void GSRendererHW::Destroy()
 void GSRendererHW::PurgeTextureCache()
 {
 	GSRenderer::PurgeTextureCache();
-	m_tc->RemoveAll();
+	m_tc->RemoveAll(true);
 }
 
 GSTexture* GSRendererHW::LookupPaletteSource(u32 CBP, u32 CPSM, u32 CBW, GSVector2i& offset, const GSVector2i& size)
diff --git a/pcsx2/GS/Renderers/HW/GSTextureCache.cpp b/pcsx2/GS/Renderers/HW/GSTextureCache.cpp
index 8a438450ca..57b23ffcfc 100644
--- a/pcsx2/GS/Renderers/HW/GSTextureCache.cpp
+++ b/pcsx2/GS/Renderers/HW/GSTextureCache.cpp
@@ -46,14 +46,18 @@ GSTextureCache::~GSTextureCache()
 	_aligned_free(s_unswizzle_buffer);
 }
 
-void GSTextureCache::RemoveAll()
+void GSTextureCache::RemoveAll(bool readback_targets)
 {
 	m_src.RemoveAll();
 
 	for (int type = 0; type < 2; type++)
 	{
 		for (auto t : m_dst[type])
+		{
+			if (readback_targets)
+				Read(t, t->m_drawn_since_read);
 			delete t;
+		}
 
 		m_dst[type].clear();
 	}
diff --git a/pcsx2/GS/Renderers/HW/GSTextureCache.h b/pcsx2/GS/Renderers/HW/GSTextureCache.h
index 06bebb6352..8be30fedc1 100644
--- a/pcsx2/GS/Renderers/HW/GSTextureCache.h
+++ b/pcsx2/GS/Renderers/HW/GSTextureCache.h
@@ -396,7 +396,7 @@ public:
 
 	void Read(Target* t, const GSVector4i& r);
 	void Read(Source* t, const GSVector4i& r);
-	void RemoveAll();
+	void RemoveAll(bool readback_targets = false);
 	void AddDirtyRectTarget(Target* target, GSVector4i rect, u32 psm, u32 bw);
 
 	GSTexture* LookupPaletteSource(u32 CBP, u32 CPSM, u32 CBW, GSVector2i& offset, const GSVector2i& size);