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[patch] Updated (hopefully final) patch for the Raspberry Pi low-latency hint

rpi_lowlatency002.diff (text/plain), 5.23 KB, created by Manuel Alfayate Corchete on 2017-10-24 00:34:49 UTC

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Creator: Manuel Alfayate Corchete

Created: 2017-10-24 00:34:49 UTC

Size: 5.23 KB

patch

obsolete

>diff -rupN SDL-ORIG/include/SDL_hints.h SDL/include/SDL_hints.h
>--- SDL-ORIG/include/SDL_hints.h	2017-10-22 18:56:01.447446228 +0200
>+++ SDL/include/SDL_hints.h	2017-10-23 14:36:20.282300573 +0200
>@@ -798,6 +798,17 @@ extern "C" {
> #define SDL_HINT_RPI_VIDEO_LAYER           "SDL_RPI_VIDEO_LAYER"
> 
> /**
>+ * \brief Tell SDL the Raspberry Pi video driver that we want double buffer only.
>+ *
>+ * By default, the EGLSwapbuffers call on the Raspberry pi 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_RPI_DOUBLE_BUFFER           "SDL_RPI_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/raspberry/SDL_rpiopengles.c SDL/src/video/raspberry/SDL_rpiopengles.c
>--- SDL-ORIG/src/video/raspberry/SDL_rpiopengles.c	2017-10-22 18:56:01.463448197 +0200
>+++ SDL/src/video/raspberry/SDL_rpiopengles.c	2017-10-23 17:09:23.135123045 +0200
>@@ -19,6 +19,8 @@
>   3. This notice may not be removed or altered from any source distribution.
> */
> #include "../../SDL_internal.h"
>+#include "SDL_hints.h"
>+#include "SDL_log.h"
> 
> #if SDL_VIDEO_DRIVER_RPI && SDL_VIDEO_OPENGL_EGL
> 
>@@ -40,8 +42,27 @@ RPI_GLES_LoadLibrary(_THIS, const char *
>     return SDL_EGL_LoadLibrary(_this, path, EGL_DEFAULT_DISPLAY, 0);
> }
> 
>+int
>+RPI_GLES_SwapWindow(_THIS, SDL_Window * window) {
>+    SDL_WindowData *wdata = ((SDL_WindowData *) window->driverdata);
>+
>+    if (!(_this->egl_data->eglSwapBuffers(_this->egl_data->egl_display, wdata->egl_surface))) {
>+        SDL_LogError(SDL_LOG_CATEGORY_VIDEO, "eglSwapBuffers failed.");
>+        return 0;
>+    }
>+
>+    /* Wait immediately for vsync (as if we only had two buffers), for low input-lag scenarios.
>+     * Run your SDL2 program with "SDL_RPI_DOUBLE_BUFFER=1 <program_name>" to enable this. */
>+    if (wdata->double_buffer) { 
>+        SDL_LockMutex(wdata->vsync_cond_mutex);
>+        SDL_CondWait(wdata->vsync_cond, wdata->vsync_cond_mutex);
>+        SDL_UnlockMutex(wdata->vsync_cond_mutex);      
>+    }
>+
>+    return 0;
>+}
>+
> SDL_EGL_CreateContext_impl(RPI)
>-SDL_EGL_SwapWindow_impl(RPI)
> SDL_EGL_MakeCurrent_impl(RPI)
> 
> #endif /* SDL_VIDEO_DRIVER_RPI && SDL_VIDEO_OPENGL_EGL */
>diff -rupN SDL-ORIG/src/video/raspberry/SDL_rpivideo.c SDL/src/video/raspberry/SDL_rpivideo.c
>--- SDL-ORIG/src/video/raspberry/SDL_rpivideo.c	2017-10-22 18:56:01.463448197 +0200
>+++ SDL/src/video/raspberry/SDL_rpivideo.c	2017-10-24 02:28:26.043272322 +0200
>@@ -214,6 +214,16 @@ RPI_SetDisplayMode(_THIS, SDL_VideoDispl
>     return 0;
> }
> 
>+static void
>+RPI_vsync_callback(DISPMANX_UPDATE_HANDLE_T u, void *data)
>+{
>+   SDL_WindowData *wdata = ((SDL_WindowData *) data);
>+
>+   SDL_LockMutex(wdata->vsync_cond_mutex);
>+   SDL_CondSignal(wdata->vsync_cond);
>+   SDL_UnlockMutex(wdata->vsync_cond_mutex);
>+}
>+
> int
> RPI_CreateWindow(_THIS, SDL_Window * window)
> {
>@@ -289,6 +299,15 @@ RPI_CreateWindow(_THIS, SDL_Window * win
>         return SDL_SetError("Could not create GLES window surface");
>     }
> 
>+    /* Start generating vsync callbacks if necesary */
>+    wdata->double_buffer = SDL_FALSE;
>+    if (SDL_GetHintBoolean(SDL_HINT_RPI_DOUBLE_BUFFER, SDL_FALSE)) { 
>+        wdata->vsync_cond = SDL_CreateCond();
>+        wdata->vsync_cond_mutex = SDL_CreateMutex();
>+        wdata->double_buffer = SDL_TRUE; 
>+        vc_dispmanx_vsync_callback(displaydata->dispman_display, RPI_vsync_callback, (void*)wdata);
>+    }
>+
>     /* Setup driver data for this window */
>     window->driverdata = wdata;
>     
>@@ -304,7 +323,22 @@ void
> RPI_DestroyWindow(_THIS, SDL_Window * window)
> {
>     SDL_WindowData *data = (SDL_WindowData *) window->driverdata;
>+    SDL_VideoDisplay *display = SDL_GetDisplayForWindow(window);
>+    SDL_DisplayData *displaydata = (SDL_DisplayData *) display->driverdata;
>+
>     if(data) {
>+	if (data->double_buffer) {
>+	    /* Wait for vsync, and then stop vsync callbacks and destroy related stuff, if needed */
>+	    SDL_LockMutex(data->vsync_cond_mutex);
>+	    SDL_CondWait(data->vsync_cond, data->vsync_cond_mutex);
>+	    SDL_UnlockMutex(data->vsync_cond_mutex);      
>+	    
>+	    vc_dispmanx_vsync_callback(displaydata->dispman_display, NULL, NULL);
>+	    
>+	    SDL_DestroyCond(data->vsync_cond);
>+	    SDL_DestroyMutex(data->vsync_cond_mutex);
>+	}
>+
> #if SDL_VIDEO_OPENGL_EGL
>         if (data->egl_surface != EGL_NO_SURFACE) {
>             SDL_EGL_DestroySurface(_this, data->egl_surface);
>diff -rupN SDL-ORIG/src/video/raspberry/SDL_rpivideo.h SDL/src/video/raspberry/SDL_rpivideo.h
>--- SDL-ORIG/src/video/raspberry/SDL_rpivideo.h	2017-10-22 18:56:01.463448197 +0200
>+++ SDL/src/video/raspberry/SDL_rpivideo.h	2017-10-23 16:51:13.575979374 +0200
>@@ -48,6 +48,12 @@ typedef struct SDL_WindowData
> #if SDL_VIDEO_OPENGL_EGL  
>     EGLSurface egl_surface;
> #endif    
>+
>+    /* Vsync callback cond and mutex */
>+    SDL_cond  *vsync_cond;
>+    SDL_mutex *vsync_cond_mutex;
>+    SDL_bool double_buffer;
>+
> } SDL_WindowData;
> 
> #define SDL_RPI_VIDEOLAYER 10000 /* High enough so to occlude everything */

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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.