From d77725bc26cadbbfc6f3a5e00c162a4b57d7964e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Henrik=20Rydg=C3=A5rd?= <hrydgard@gmail.com>
Date: Sat, 17 May 2025 10:17:36 +0200
Subject: [PATCH] libretro: Fix GPU init. Had to revert to the old way for
 libretro, something is ordering-sensitive here.

Fixes #20350
---
 Core/System.cpp                   | 37 +++++++++++++++++++------------
 libretro/LibretroD3D11Context.cpp |  7 +++++-
 libretro/README_WINDOWS.txt       | 12 ++++++----
 libretro/libretro.cpp             |  4 +++-
 4 files changed, 40 insertions(+), 20 deletions(-)

diff --git a/Core/System.cpp b/Core/System.cpp
index b2e41a986f..41d00f0738 100644
--- a/Core/System.cpp
+++ b/Core/System.cpp
@@ -512,6 +512,21 @@ void PSP_ForceDebugStats(bool enable) {
 	_assert_(coreCollectDebugStatsCounter >= 0);
 }
 
+static void InitGPU(std::string *error_string) {
+	if (!gpu) {  // should be!
+		INFO_LOG(Log::Loader, "Starting graphics...");
+		Draw::DrawContext *draw = g_CoreParameter.graphicsContext ? g_CoreParameter.graphicsContext->GetDrawContext() : nullptr;
+		// This set the `gpu` global.
+		GPUCore gpuCore = PSP_CoreParameter().gpuCore;
+		bool success = GPU_Init(gpuCore, g_CoreParameter.graphicsContext, draw);
+		if (!success) {
+			*error_string = "Unable to initialize rendering engine.";
+			CPU_Shutdown(false);
+			g_bootState = BootState::Failed;
+		}
+	}
+}
+
 bool PSP_InitStart(const CoreParameter &coreParam) {
 	if (g_bootState != BootState::Off) {
 		ERROR_LOG(Log::Loader, "Can't start loader thread - already on.");
@@ -576,20 +591,10 @@ bool PSP_InitStart(const CoreParameter &coreParam) {
 		}
 
 		// Initialize the GPU as far as we can here (do things like load cache files).
-
-		if (!gpu) {  // should be!
-			INFO_LOG(Log::Loader, "Starting graphics...");
-			Draw::DrawContext *draw = g_CoreParameter.graphicsContext ? g_CoreParameter.graphicsContext->GetDrawContext() : nullptr;
-			// This set the `gpu` global.
-			GPUCore gpuCore = PSP_CoreParameter().gpuCore;
-			bool success = GPU_Init(gpuCore, g_CoreParameter.graphicsContext, draw);
-			if (!success) {
-				*error_string = "Unable to initialize rendering engine.";
-				CPU_Shutdown(false);
-				g_bootState = BootState::Failed;
-			}
-		}
-
+		_dbg_assert_(!gpu);
+#ifndef __LIBRETRO__
+		InitGPU(error_string);
+#endif
 		g_bootState = BootState::Complete;
 	});
 
@@ -619,6 +624,10 @@ BootState PSP_InitUpdate(std::string *error_string) {
 		return BootState::Failed;
 	}
 
+#ifdef __LIBRETRO__
+	InitGPU(error_string);
+#endif
+
 	// Ok, async part of the boot completed, let's finish up things on the main thread.
 	if (gpu) {
 		gpu->FinishInitOnMainThread();
diff --git a/libretro/LibretroD3D11Context.cpp b/libretro/LibretroD3D11Context.cpp
index 55d1613ef0..5950e35222 100644
--- a/libretro/LibretroD3D11Context.cpp
+++ b/libretro/LibretroD3D11Context.cpp
@@ -22,11 +22,16 @@ bool LibretroD3D11Context::Init() {
 
 void LibretroD3D11Context::CreateDrawContext() {
    retro_hw_render_interface_d3d11 *d3d11Interface = nullptr;
-   if (!Libretro::environ_cb(RETRO_ENVIRONMENT_GET_HW_RENDER_INTERFACE, (void **)&d3d11Interface) || !d3d11Interface) {
+   if (!Libretro::environ_cb(RETRO_ENVIRONMENT_GET_HW_RENDER_INTERFACE, (void **)&d3d11Interface)) {
       ERROR_LOG(Log::G3D, "Failed to get HW rendering interface!\n");
       return;
    }
 
+   if (!d3d11Interface) {
+      ERROR_LOG(Log::G3D, "D3D11 interface was null!\n");
+      return;
+   }
+
    if (d3d11Interface->interface_version != RETRO_HW_RENDER_INTERFACE_D3D11_VERSION) {
       ERROR_LOG(Log::G3D, "HW render interface mismatch, expected %u, got %u!\n", RETRO_HW_RENDER_INTERFACE_D3D11_VERSION, d3d11Interface->interface_version);
       return;
diff --git a/libretro/README_WINDOWS.txt b/libretro/README_WINDOWS.txt
index 4eb43f7d9d..86db0d7523 100644
--- a/libretro/README_WINDOWS.txt
+++ b/libretro/README_WINDOWS.txt
@@ -10,14 +10,18 @@ pacman -S make
 
 Start Retroarch ones to create the cores directory.
 
-Then use the following in msys:
+Then use the following in msys (edit the last part as appropriate):
 
-> cd libretro
-> make platform=windows_msvc2019_desktop_x64 -j32 && cp ppsspp_libretro.* /d/retroarch/cores
+```
+cd libretro
+make platform=windows_msvc2019_desktop_x64 -j32 && cp ppsspp_libretro.* /d/retroarch/cores
+```
 
 To make a debug build:
 
-> make DEBUG=1 platform=windows_msvc2019_desktop_x64 -j32
+```
+make DEBUG=1 platform=windows_msvc2019_desktop_x64 -j32 && cp ppsspp_libretro.* /d/retroarch/cores
+```
 
 Note that the latter part copies the DLL/PDB into wherever retroarch reads it from. Might need to adjust the path,
 and adjust -j32 depending on your number of logical CPUs - might not need that many threads (or you might need more...).
diff --git a/libretro/libretro.cpp b/libretro/libretro.cpp
index 727012b5b8..428dbbdad3 100644
--- a/libretro/libretro.cpp
+++ b/libretro/libretro.cpp
@@ -1321,8 +1321,9 @@ namespace Libretro
    static void EmuFrame()
    {
       ctx->SetRenderTarget();
-      if (ctx->GetDrawContext())
+      if (ctx->GetDrawContext()) {
          ctx->GetDrawContext()->BeginFrame(Draw::DebugFlags::NONE);
+      }
 
       if (gpu)
          gpu->BeginHostFrame();
@@ -1451,6 +1452,7 @@ bool retro_load_game(const struct retro_game_info *game)
    retro_check_backend();
 
    ctx       = LibretroGraphicsContext::CreateGraphicsContext();
+
    INFO_LOG(Log::System, "Using %s backend", ctx->Ident());
 
    Core_SetGraphicsContext(ctx);