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[patch] Small patch for low latency mode hint on the KMSDRM video driver

patch_kmsdrm_lowlatency001.diff (text/plain), 1.90 KB, created by Manuel Alfayate Corchete on 2017-10-21 12:12:40 UTC

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Creator: Manuel Alfayate Corchete

Created: 2017-10-21 12:12:40 UTC

Size: 1.90 KB

patch

obsolete

>diff -rupN SDL-ORIG/include/SDL_hints.h SDL/include/SDL_hints.h
>--- SDL-ORIG/include/SDL_hints.h	2017-10-21 13:33:36.495309807 +0200
>+++ SDL/include/SDL_hints.h	2017-10-21 13:42:35.132013429 +0200
>@@ -798,6 +798,16 @@ extern "C" {
> #define SDL_HINT_RPI_VIDEO_LAYER           "SDL_RPI_VIDEO_LAYER"
> 
> /**
>+ * \brief Tell SDL the KMS/DRM video driver that we want double buffer only.
>+ *
>+ * By default, KMS/DRM will use a triple buffer solution that wastes no CPU
>+ * time on waiting for vsync after issuing a flip, but introduces a frame of
>+ * latency. Waiting for vsync immediately after issuing a flip, on the other
>+ * hand, is recommended for cases where low latency is an important factor. 
>+ */
>+#define SDL_HINT_KMSDRM_DOUBLE_BUFFER      "SDL_KMSDRM_DOUBLE_BUFFER"
>+
>+/**
>  *  \brief  A variable controlling what driver to use for OpenGL ES contexts.
>  *
>  *  On some platforms, currently Windows and X11, OpenGL drivers may support
>diff -rupN SDL-ORIG/src/video/kmsdrm/SDL_kmsdrmopengles.c SDL/src/video/kmsdrm/SDL_kmsdrmopengles.c
>--- SDL-ORIG/src/video/kmsdrm/SDL_kmsdrmopengles.c	2017-10-21 13:33:36.507310269 +0200
>+++ SDL/src/video/kmsdrm/SDL_kmsdrmopengles.c	2017-10-21 14:03:27.428591519 +0200
>@@ -24,6 +24,7 @@
> #if SDL_VIDEO_DRIVER_KMSDRM && SDL_VIDEO_OPENGL_EGL
> 
> #include "SDL_log.h"
>+#include "SDL_hints.h"
> 
> #include "SDL_kmsdrmvideo.h"
> #include "SDL_kmsdrmopengles.h"
>@@ -171,6 +172,12 @@ KMSDRM_GLES_SwapWindow(_THIS, SDL_Window
>         } else {
>             SDL_LogError(SDL_LOG_CATEGORY_VIDEO, "Could not queue pageflip: %d", ret);
>         }
>+
>+        /* Wait immediately for vsync (as if we only had two buffers), for low input-lag scenarios.
>+           Run your SDL2 program with "SDL_KMSDRM_DOUBLE_BUFFER=1 <program_name>" to enable this. */
>+        if (SDL_GetHintBoolean(SDL_HINT_KMSDRM_DOUBLE_BUFFER, SDL_FALSE)) { 
>+            KMSDRM_WaitPageFlip(_this, wdata, -1);
>+        }
>     }
> 
>     return 0;

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We are currently migrating Bugzilla to GitHub issues.Any changes made to the bug tracker now will be lost, so please do not post new bugs or make changes to them.When we're done, all bug URLs will redirect to their equivalent location on the new bug tracker.

We are currently migrating Bugzilla to GitHub issues.
Any changes made to the bug tracker now will be lost, so please do not post new bugs or make changes to them.
When we're done, all bug URLs will redirect to their equivalent location on the new bug tracker.