From 39f224b3a65f10f3957d240582c63fafd7d2d524 Mon Sep 17 00:00:00 2001
From: "Carsten Haitzler (Rasterman)" <raster@rasterman.com>
Date: Sun, 17 Feb 2019 13:33:25 +0000
Subject: [PATCH] ecore drm2 - work around kms/drm bug seemingly when no flip
 event comes

so we request a flip so we can do vsync events. the flip event never
comes. i am not sure why it never comes, but we ask and nothing
arrives, and this basically halts all rendering in wayland compositor
mode as we are syncing rendering to vsync (of course). put in a
timeout of 0.05s (50ms) to try ask again if the event never comes and
log the error. this is a pretty useful workaround becauswe having your
entire display freeze is a ... bad thing.

@fix
---
 src/lib/ecore_drm2/ecore_drm2_fb.c      | 30 +++++++++++++++++++++++++
 src/lib/ecore_drm2/ecore_drm2_outputs.c |  2 ++
 src/lib/ecore_drm2/ecore_drm2_private.h |  2 ++
 3 files changed, 34 insertions(+)

diff --git a/src/lib/ecore_drm2/ecore_drm2_fb.c b/src/lib/ecore_drm2/ecore_drm2_fb.c
index 33c0e27570..6888a3c2c1 100644
--- a/src/lib/ecore_drm2/ecore_drm2_fb.c
+++ b/src/lib/ecore_drm2/ecore_drm2_fb.c
@@ -263,6 +263,11 @@ ecore_drm2_fb_flip_complete(Ecore_Drm2_Output *output)
 
    EINA_SAFETY_ON_NULL_RETURN_VAL(output, EINA_FALSE);
 
+   if (output->flip_timeout)
+     {
+        ecore_timer_del(output->flip_timeout);
+        output->flip_timeout = NULL;
+     }
    if (output->current.fb && (output->current.fb != output->pending.fb))
      _ecore_drm2_fb_buffer_release(output, &output->current);
 
@@ -428,6 +433,21 @@ err:
    return EINA_FALSE;
 }
 
+static int _fb_atomic_flip(Ecore_Drm2_Output *output);
+static int _fb_flip(Ecore_Drm2_Output *output);
+
+static Eina_Bool
+_cb_flip_timeout(void *data)
+{
+   Ecore_Drm2_Output *output = data;
+
+   output->flip_timeout = NULL;
+   ERR("flip event callback timout 0.05sec - try again");
+   if (_ecore_drm2_use_atomic) _fb_atomic_flip(output);
+   else _fb_flip(output);
+   return EINA_FALSE;
+}
+
 static int
 _fb_atomic_flip(Ecore_Drm2_Output *output)
 {
@@ -453,6 +473,11 @@ _fb_atomic_flip(Ecore_Drm2_Output *output)
         ERR("Failed Atomic Commit: %m");
         return -1;
      }
+   else
+     {
+        if (output->flip_timeout) ecore_timer_del(output->flip_timeout);
+        output->flip_timeout = ecore_timer_add(0.05, _cb_flip_timeout, output);
+     }
 
    return 0;
 }
@@ -526,6 +551,11 @@ _fb_flip(Ecore_Drm2_Output *output)
                }
              usleep(100);
           }
+        else
+          {
+             if (output->flip_timeout) ecore_timer_del(output->flip_timeout);
+             output->flip_timeout = ecore_timer_add(0.05, _cb_flip_timeout, output);
+          }
      }
    while (repeat);
 
diff --git a/src/lib/ecore_drm2/ecore_drm2_outputs.c b/src/lib/ecore_drm2/ecore_drm2_outputs.c
index 557e33f5ab..a820f7d3f5 100644
--- a/src/lib/ecore_drm2/ecore_drm2_outputs.c
+++ b/src/lib/ecore_drm2/ecore_drm2_outputs.c
@@ -916,6 +916,8 @@ _output_destroy(Ecore_Drm2_Device *dev EINA_UNUSED, Ecore_Drm2_Output *output)
    eina_stringshare_del(output->serial);
    eina_stringshare_del(output->relative.to);
 
+   if (output->flip_timeout) ecore_timer_del(output->flip_timeout);
+
    sym_drmModeFreeProperty(output->dpms);
    free(output->edid.blob);
 
diff --git a/src/lib/ecore_drm2/ecore_drm2_private.h b/src/lib/ecore_drm2/ecore_drm2_private.h
index 490f1665e4..d1a749a871 100644
--- a/src/lib/ecore_drm2/ecore_drm2_private.h
+++ b/src/lib/ecore_drm2/ecore_drm2_private.h
@@ -252,6 +252,8 @@ struct _Ecore_Drm2_Output
    /* unused when doing atomic */
    drmModePropertyPtr dpms;
 
+   Ecore_Timer *flip_timeout;
+
    Ecore_Drm2_Output_Mode *current_mode;
    Eina_List *modes;