context_drm_egl: simplify and fix delayed rendering with vo_gpu_next

This backend is a special case where the state of the frame (i.e. is it
still) needs to be taken into account when flipping the page because it
does its own fencing. vo_gpu_next never calls the submit_frame API in
ra_swapchain which meant the drm backend wasn't aware of the state of
the frames and thus couldn't respond. This is a bit weird though because
in vo_gpu we actually want the ra_gl_ctx_submit_frame call after the
custom external drm_egl_submit_frame. But we don't want this in
vo_gpu_next, we only want the state update. Be lazy and just compare the
vo_drivers, but the way this is currently designed feels wrong. Fixes
delayed OSD rendering when you play a still image like an audio
file with cover art.

video/out/opengl/context.c

@@ -241,6 +241,10 @@ bool ra_gl_ctx_submit_frame(struct ra_swapchain *sw, const struct vo_frame *fram
     struct priv *p = sw->priv;
     GL *gl = p->gl;
 
+    // Dumb hack for drm_egl and vo_gpu_next.
+    if (vo_is_gpu_next(sw->ctx->vo))
+        return true;
+
     if (p->opts->use_glfinish)
         gl->Finish();
 

video/out/opengl/context_drm_egl.c

@@ -388,20 +388,6 @@ static void wait_fence(struct ra_ctx *ctx)
     }
 }
 
-static bool drm_egl_start_frame(struct ra_swapchain *sw, struct ra_fbo *out_fbo)
-{
-    struct ra_ctx *ctx = sw->ctx;
-    struct priv *p = ctx->priv;
-    struct vo_drm_state *drm = ctx->vo->drm;
-
-    if (!drm->atomic_context->request) {
-        drm->atomic_context->request = drmModeAtomicAlloc();
-        p->drm_params.atomic_request_ptr = &drm->atomic_context->request;
-    }
-
-    return ra_gl_ctx_start_frame(sw, out_fbo);
-}
-
 static bool drm_egl_submit_frame(struct ra_swapchain *sw, const struct vo_frame *frame)
 {
     struct ra_ctx *ctx = sw->ctx;
@@ -419,6 +405,11 @@ static void drm_egl_swap_buffers(struct ra_swapchain *sw)
     struct vo_drm_state *drm = ctx->vo->drm;
     const bool drain = drm->paused || drm->still;  // True when we need to drain the swapchain
 
+    if (!drm->atomic_context->request) {
+        drm->atomic_context->request = drmModeAtomicAlloc();
+        p->drm_params.atomic_request_ptr = &drm->atomic_context->request;
+    }
+
     if (!drm->active)
         return;
 
@@ -452,7 +443,6 @@ static void drm_egl_swap_buffers(struct ra_swapchain *sw)
 }
 
 static const struct ra_swapchain_fns drm_egl_swapchain = {
-    .start_frame   = drm_egl_start_frame,
     .submit_frame  = drm_egl_submit_frame,
     .swap_buffers  = drm_egl_swap_buffers,
 };

video/out/vo.c

@@ -860,6 +860,12 @@ bool vo_is_ready_for_frame(struct vo *vo, int64_t next_pts)
     return r;
 }
 
+// Needed by egl_drm
+bool vo_is_gpu_next(struct vo *vo)
+{
+    return vo && vo->driver && vo->driver == &video_out_gpu_next;
+}
+
 // Check if the VO reports that the mpv window is visible.
 bool vo_is_visible(struct vo *vo)
 {

video/out/vo.h

@@ -532,6 +532,7 @@ int vo_reconfig2(struct vo *vo, struct mp_image *img);
 
 int vo_control(struct vo *vo, int request, void *data);
 void vo_control_async(struct vo *vo, int request, void *data);
+bool vo_is_gpu_next(struct vo *vo);
 bool vo_is_ready_for_frame(struct vo *vo, int64_t next_pts);
 bool vo_is_visible(struct vo *vo);
 void vo_queue_frame(struct vo *vo, struct vo_frame *frame);

video/out/vo_gpu_next.c

@@ -1170,6 +1170,7 @@ done:
     if (!valid) // clear with purple to indicate error
         pl_tex_clear(gpu, swframe.fbo, (float[4]){ 0.5, 0.0, 1.0, 1.0 });
 
+    sw->fns->submit_frame(sw, frame); // for drm_egl
     pl_gpu_flush(gpu);
     p->frame_pending = true;
     return VO_TRUE;