GPU: Insert null field buffer if display disabled

Don't throw away all buffers. 240p Test Suite flips display disabled
during vblank every frame.

src/core/gpu.cpp

@@ -1512,9 +1512,6 @@ void GPU::WriteGP1(u32 value)
       DEBUG_LOG("Display {}", disable ? "disabled" : "enabled");
       SynchronizeCRTC();
 
-      if (!m_GPUSTAT.display_disable && disable && IsInterlacedDisplayEnabled())
-        ClearDisplay();
-
       m_GPUSTAT.display_disable = disable;
     }
     break;

src/core/gpu_hw.cpp

@@ -3976,6 +3976,9 @@ void GPU_HW::UpdateDisplay(const GPUBackendUpdateDisplayCommand* cmd)
   if (cmd->display_disabled)
   {
     m_presenter.ClearDisplayTexture();
+    if (interlaced)
+      m_presenter.Deinterlace(interlaced_field);
+
     return;
   }
   else if (!cmd->display_24bit && line_skip == 0 && !IsUsingMultisampling() &&

src/core/gpu_presenter.cpp

@@ -1006,13 +1006,16 @@ void GPUPresenter::DestroyDeinterlaceTextures()
 
 bool GPUPresenter::Deinterlace(u32 field)
 {
-  GPUTexture* src = m_display_texture;
+  GPUTexture* const src = m_display_texture;
+  if (src)
+    src->MakeReadyForSampling();
+
   const u32 x = m_display_texture_view_x;
   const u32 y = m_display_texture_view_y;
   const u32 width = m_display_texture_view_width;
   const u32 height = m_display_texture_view_height;
 
-  const auto copy_to_field_buffer = [&](u32 buffer) {
+  const auto copy_to_field_buffer = [this, &src, &x, &y, &width, &height](u32 buffer) {
     if (!g_gpu_device->ResizeTexture(&m_deinterlace_buffers[buffer], width, height, GPUTexture::Type::Texture,
                                      src->GetFormat(), GPUTexture::Flags::None, false)) [[unlikely]]
     {
@@ -1027,8 +1030,6 @@ bool GPUPresenter::Deinterlace(u32 field)
     return true;
   };
 
-  src->MakeReadyForSampling();
-
   switch (g_gpu_settings.display_deinterlacing_mode)
   {
     case DisplayDeinterlacingMode::Disabled:
@@ -1072,13 +1073,20 @@ bool GPUPresenter::Deinterlace(u32 field)
       const u32 this_buffer = m_current_deinterlace_buffer;
       m_current_deinterlace_buffer = (m_current_deinterlace_buffer + 1u) % NUM_BLEND_BUFFERS;
       GL_INS_FMT("Current buffer: {}", this_buffer);
-      if (!DeinterlaceSetTargetSize(width, height, false) || !copy_to_field_buffer(this_buffer)) [[unlikely]]
+      if (src)
       {
-        ClearDisplayTexture();
-        return false;
+        if (!DeinterlaceSetTargetSize(width, height, false) || !copy_to_field_buffer(this_buffer))
+        {
+          ClearDisplayTexture();
+          return false;
+        }
+      }
+      else
+      {
+        // Clear the buffer, make it sample black.
+        GL_INS("No source texture, clearing deinterlace buffer");
+        g_gpu_device->RecycleTexture(std::move(m_deinterlace_buffers[this_buffer]));
       }
-
-      copy_to_field_buffer(this_buffer);
 
       // TODO: could be implemented with alpha blending instead..
       g_gpu_device->InvalidateRenderTarget(m_deinterlace_texture.get());
@@ -1103,10 +1111,20 @@ bool GPUPresenter::Deinterlace(u32 field)
       const u32 full_height = height * 2;
       m_current_deinterlace_buffer = (m_current_deinterlace_buffer + 1u) % DEINTERLACE_BUFFER_COUNT;
       GL_INS_FMT("Current buffer: {}", this_buffer);
-      if (!DeinterlaceSetTargetSize(width, full_height, false) || !copy_to_field_buffer(this_buffer)) [[unlikely]]
+
+      if (src)
       {
-        ClearDisplayTexture();
-        return false;
+        if (!DeinterlaceSetTargetSize(width, full_height, false) || !copy_to_field_buffer(this_buffer)) [[unlikely]]
+        {
+          ClearDisplayTexture();
+          return false;
+        }
+      }
+      else
+      {
+        // Clear the buffer, make it sample black.
+        GL_INS("No source texture, clearing deinterlace buffer");
+        g_gpu_device->RecycleTexture(std::move(m_deinterlace_buffers[this_buffer]));
       }
 
       g_gpu_device->SetRenderTarget(m_deinterlace_texture.get());

src/core/gpu_sw.cpp

@@ -385,14 +385,18 @@ void GPU_SW::UpdateDisplay(const GPUBackendUpdateDisplayCommand* cmd)
 {
   if (!g_gpu_settings.gpu_show_vram)
   {
+    const u32 field = BoolToUInt32(cmd->interlaced_display_field);
+
     if (cmd->display_disabled)
     {
       m_presenter.ClearDisplayTexture();
+      if (cmd->interlaced_display_enabled)
+        m_presenter.Deinterlace(field);
+
       return;
     }
 
     const bool is_24bit = cmd->display_24bit;
-    const u32 field = BoolToUInt32(cmd->interlaced_display_field);
     const u32 line_skip = BoolToUInt32(cmd->interlaced_display_interleaved);
     const u32 src_x = is_24bit ? cmd->X : cmd->display_vram_left;
     const u32 skip_x = is_24bit ? (cmd->display_vram_left - cmd->X) : 0;