Scanline sync corrections

- Stop trying to force vsync off when scanline sync is enabled
- Better minimum core time

Author: sonninnos

gfx/common/vulkan_common.c

@@ -1831,7 +1831,7 @@ bool vulkan_create_swapchain(gfx_ctx_vulkan_data_t *vk,
    VkPresentModeKHR swapchain_present_mode = VK_PRESENT_MODE_FIFO_KHR;
    VkCompositeAlphaFlagBitsKHR composite   = VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR;
    settings_t                    *settings = config_get_ptr();
-   bool vsync                              = settings->bools.video_vsync && !settings->bools.video_scanline_sync;
+   bool vsync                              = settings->bools.video_vsync;
    bool adaptive_vsync                     = settings->bools.video_adaptive_vsync;
 #ifdef VK_USE_PLATFORM_WIN32_KHR
    bool video_windowed_fullscreen          = settings->bools.video_windowed_fullscreen;

gfx/drivers/d3d11.c

@@ -3240,6 +3240,11 @@ static void *d3d11_gfx_init(const video_info_t* video,
    if (settings->bools.video_waitable_swapchains)
       d3d11->flags |=  D3D11_ST_FLAG_WAITABLE_SWAPCHAINS;
 
+   if (video->vsync)
+      d3d11->flags |=  D3D11_ST_FLAG_VSYNC;
+   else
+      d3d11->flags &= ~D3D11_ST_FLAG_VSYNC;
+
 #ifdef __WINRT__
    if (!d3d11_init_swapchain(d3d11,
             d3d11->vp.full_width,
@@ -3275,11 +3280,6 @@ static void *d3d11_gfx_init(const video_info_t* video,
    else
       d3d11->flags       &= ~D3D11_ST_FLAG_KEEP_ASPECT;
 
-   if (video->vsync)
-      d3d11->flags       |=  D3D11_ST_FLAG_VSYNC;
-   else
-      d3d11->flags       &= ~D3D11_ST_FLAG_VSYNC;
-
    d3d11->format          = (video->rgb32)
          ? DXGI_FORMAT_B8G8R8X8_UNORM : DXGI_FORMAT_B5G6R5_UNORM;
 

gfx/drivers/d3d12.c

@@ -4288,6 +4288,11 @@ static void *d3d12_gfx_init(const video_info_t* video,
    else
       d3d12->flags &= ~D3D12_ST_FLAG_WAITABLE_SWAPCHAINS;
 
+   if (video->vsync)
+      d3d12->flags |=  D3D12_ST_FLAG_VSYNC;
+   else
+      d3d12->flags &= ~D3D12_ST_FLAG_VSYNC;
+
    d3d_input_driver(settings->arrays.input_driver,
          settings->arrays.input_joypad_driver, input, input_data);
 
@@ -4427,11 +4432,6 @@ static void *d3d12_gfx_init(const video_info_t* video,
    else
       d3d12->flags             &= ~D3D12_ST_FLAG_KEEP_ASPECT;
 
-   if (video->vsync)
-      d3d12->flags             |=  D3D12_ST_FLAG_VSYNC;
-   else
-      d3d12->flags             &= ~D3D12_ST_FLAG_VSYNC;
-
    d3d12->format                = (video->rgb32)
       ? DXGI_FORMAT_B8G8R8X8_UNORM : DXGI_FORMAT_B5G6R5_UNORM;
 

gfx/video_driver.c

@@ -5323,13 +5323,15 @@ static INLINE void video_driver_scanline_before_frame(video_driver_state_t *vide
       uint16_t frame_time_target,
       uint16_t core_run_time)
 {
-   uint16_t video_height = video_st->height;
-   int16_t scanline_next = video_st->scanline[SCANLINE_NEXT];
-   int16_t scanline_hold = video_st->scanline[SCANLINE_HOLD];
-   int16_t scanline      = video_driver_scanline_get();
+   uint16_t video_height  = video_st->height;
+   int16_t scanline_next  = video_st->scanline[SCANLINE_NEXT];
+   int16_t scanline_hold  = video_st->scanline[SCANLINE_HOLD];
+   int16_t scanline_blank = video_st->scanline[SCANLINE_TOTAL] - video_height;
+   int16_t scanline       = video_driver_scanline_get();
 
-   /* Assume at least some usage in menu */
-   core_run_time = core_run_time < 1000 ? 1000 : core_run_time;
+   /* Minimum usage is vblank */
+   uint16_t min_run_time  = (scanline_blank > 0) ? (double)scanline_blank / (double)video_height * (double)frame_time_target : 1000;
+   core_run_time          = (core_run_time < min_run_time) ? min_run_time : core_run_time;
 
    /* Disable if unsupported */
    if (scanline < 0)
@@ -5357,8 +5359,7 @@ static INLINE void video_driver_scanline_before_frame(video_driver_state_t *vide
    /* Allow change */
    if (!scanline_hold)
    {
-      int16_t scanline_blank = video_st->scanline[SCANLINE_TOTAL] - video_height;
-      int16_t corelines      = video_height * ((double)core_run_time / (double)frame_time_target);
+      int16_t corelines = video_height * ((double)core_run_time / (double)frame_time_target);
 
       /* Fine-tuning */
       if (     scanline > -scanline_blank
@@ -5400,7 +5401,9 @@ static INLINE void video_driver_scanline_after_frame(video_driver_state_t *video
    uint16_t video_height   = video_st->height;
    int16_t scanline_next   = video_st->scanline[SCANLINE_NEXT];
    int16_t scanline_total  = video_st->scanline[SCANLINE_TOTAL];
+   int16_t scanline_blank  = video_st->scanline[SCANLINE_TOTAL] - video_height;
    int16_t scanline_target = (scanline_next < 0) ? video_height + scanline_next : scanline_next;
+   uint16_t min_run_time   = (scanline_blank > 0) ? (double)scanline_blank / (double)video_height * (double)frame_time_target : 1000;
    bool init               = (!scanline_total) ? true : false;
    bool wait               = true;
 
@@ -5412,6 +5415,9 @@ static INLINE void video_driver_scanline_after_frame(video_driver_state_t *video
    if (scanline_next == 1)
       scanline_target = video_height - 1;
 
+   /* Minimum usage is vblank */
+   core_run_time = (core_run_time < min_run_time) ? min_run_time : core_run_time;
+
    /* Use CPU friendlier sleep as much as possible */
    if (wait && frame_time_target > core_run_time)
    {

intl/msg_hash_us.h

@@ -2616,7 +2616,7 @@ MSG_HASH(
    )
 MSG_HASH(
    MENU_ENUM_SUBLABEL_VIDEO_SCANLINE_SYNC,
-   "Synchronize video presentation to scanline position. Reduces latency at the cost of a higher risk of tearing."
+   "Synchronize video presentation to scanline position. Reduces latency at the cost of a higher risk of tearing. VSync must be disabled."
    )
 MSG_HASH(
    MENU_ENUM_LABEL_VALUE_VIDEO_FRAME_DELAY,

runloop.c

@@ -4494,13 +4494,6 @@ void runloop_set_video_swap_interval(
       return;
    }
 
-   /* Scanline sync needs swap interval 0 */
-   if (settings->bools.video_scanline_sync)
-   {
-      runloop_st->video_swap_interval_auto = 0;
-      return;
-   }
-
    /* > If VRR is enabled, swap interval is irrelevant,
     *   just set to 1
     * > If core fps is higher than display refresh rate,