From: Jean-Philippe Andre <jp.andre@samsung.com>
Date: Tue, 18 Oct 2016 08:36:43 +0000 (+0900)
Subject: wayland_shm: Add swap mode fallback when buffer age changes
X-Git-Tag: upstream/1.20.0~4043
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=62ca4486ea30fd63a5589ea7af373a5cb9982031;p=platform%2Fupstream%2Fefl.git

wayland_shm: Add swap mode fallback when buffer age changes

This copies the behaviour in opengl_x11 engine, where the buffer
age needs to be continuously the same to be taken into account.
If the age varies, then we fallback to a full redraw.

Apparently this fixes issues on actual devices. I tested this
patch in weston (I didn't have issues before and buffer age is 1).
---

diff --git a/src/modules/evas/engines/wayland_shm/evas_engine.h b/src/modules/evas/engines/wayland_shm/evas_engine.h
index 7436c6b..bae4e37 100644
--- a/src/modules/evas/engines/wayland_shm/evas_engine.h
+++ b/src/modules/evas/engines/wayland_shm/evas_engine.h
@@ -107,6 +107,7 @@ struct _Outbuf
    int rotation;
    int onebuf;
    int num_buff;
+   int prev_age;
    Outbuf_Depth depth;
 
    Evas_Engine_Info_Wayland_Shm *info;
diff --git a/src/modules/evas/engines/wayland_shm/evas_outbuf.c b/src/modules/evas/engines/wayland_shm/evas_outbuf.c
index 6dafa85..b372864 100644
--- a/src/modules/evas/engines/wayland_shm/evas_outbuf.c
+++ b/src/modules/evas/engines/wayland_shm/evas_outbuf.c
@@ -314,17 +314,22 @@ _evas_outbuf_flush(Outbuf *ob, Tilebuf_Rect *rects EINA_UNUSED, Evas_Render_Mode
 Render_Engine_Swap_Mode 
 _evas_outbuf_swap_mode_get(Outbuf *ob)
 {
+   Render_Engine_Swap_Mode mode;
    int age;
 
    LOGFN(__FILE__, __LINE__, __FUNCTION__);
 
    age = ob->surface->funcs.assign(ob->surface);
-   if (age == 1) return MODE_COPY;
-   else if (age == 2) return MODE_DOUBLE;
-   else if (age == 3) return MODE_TRIPLE;
-   else if (age == 4) return MODE_QUADRUPLE;
+   if (age == 1) mode = MODE_COPY;
+   else if (age == 2) mode = MODE_DOUBLE;
+   else if (age == 3) mode = MODE_TRIPLE;
+   else if (age == 4) mode = MODE_QUADRUPLE;
+   else mode = MODE_FULL;
 
-   return MODE_FULL;
+   if (ob->prev_age != age) mode = MODE_FULL;
+   ob->prev_age = age;
+
+   return mode;
 }
 
 int