From 0584fc81a2960c47426560fa52bab675b10527b5 Mon Sep 17 00:00:00 2001
From: Derek Foreman <derekf@osg.samsung.com>
Date: Fri, 28 Jul 2017 15:25:25 -0500
Subject: [PATCH] ecore_drm2: Add a fallback method for vblank waiting

We can't depend on vblank waits being implemented by the driver, but we
can count on page flips functioning, so add a fallback that does a page
flip and waits for it.
---
 src/lib/ecore_drm2/ecore_drm2_outputs.c | 49 +++++++++++++++++++++++++
 src/lib/ecore_drm2/ecore_drm2_private.h |  2 +
 2 files changed, 51 insertions(+)

diff --git a/src/lib/ecore_drm2/ecore_drm2_outputs.c b/src/lib/ecore_drm2/ecore_drm2_outputs.c
index fba4be0c8d..85504a0d6d 100644
--- a/src/lib/ecore_drm2/ecore_drm2_outputs.c
+++ b/src/lib/ecore_drm2/ecore_drm2_outputs.c
@@ -1583,6 +1583,49 @@ ecore_drm2_output_subpixel_get(const Ecore_Drm2_Output *output)
    return output->subpixel;
 }
 
+static void
+_blank_fallback_handler(int fd EINA_UNUSED, unsigned int frame EINA_UNUSED, unsigned int sec, unsigned int usec, void *data EINA_UNUSED)
+{
+   Ecore_Drm2_Output *output;
+
+   output = data;
+   output->fallback_usec = usec;
+   output->fallback_sec = sec;
+}
+static int
+_blanktime_fallback(Ecore_Drm2_Output *output, int sequence, long *sec, long *usec)
+{
+   drmEventContext ctx;
+   int ret;
+
+   /* Too lazy to loop for > 1, and don't want to block for < 1 */
+   if (sequence != 1) return -1;
+
+   /* If we got here with a flip waiting to complete we can do nothing. */
+   if (output->pending.fb) return -1;
+
+   if (!output->current.fb) return -1;
+
+   memset(&ctx, 0, sizeof(ctx));
+   ctx.version = 2;
+   ctx.page_flip_handler = _blank_fallback_handler;
+   ctx.vblank_handler = NULL;
+
+   ret = sym_drmModePageFlip(output->current.fb->fd, output->crtc_id,
+                             output->current.fb->id, DRM_MODE_PAGE_FLIP_EVENT,
+                             output);
+   if (ret < 0) return -1;
+   do
+     {
+        ret = sym_drmHandleEvent(output->current.fb->fd, &ctx);
+     } while (ret != 0 && errno == EAGAIN);
+   if (ret < 0) return -1;
+
+   *sec = output->fallback_sec;
+   *usec = output->fallback_usec;
+   return 0;
+}
+
 EAPI Eina_Bool
 ecore_drm2_output_blanktime_get(Ecore_Drm2_Output *output, int sequence, long *sec, long *usec)
 {
@@ -1597,6 +1640,12 @@ ecore_drm2_output_blanktime_get(Ecore_Drm2_Output *output, int sequence, long *s
   v.request.type = DRM_VBLANK_RELATIVE;
   v.request.sequence = sequence;
   ret = sym_drmWaitVBlank(output->fd, &v);
+  if (ret)
+    {
+       ret = _blanktime_fallback(output, sequence, sec, usec);
+       if (ret) return EINA_FALSE;
+       return EINA_TRUE;
+    }
   if (ret) return EINA_FALSE;
   if (v.reply.tval_sec < 0) return EINA_FALSE;
   if (v.reply.tval_usec < 0) return EINA_FALSE;
diff --git a/src/lib/ecore_drm2/ecore_drm2_private.h b/src/lib/ecore_drm2/ecore_drm2_private.h
index c8c2bf66c2..a85cb0c2d5 100644
--- a/src/lib/ecore_drm2/ecore_drm2_private.h
+++ b/src/lib/ecore_drm2/ecore_drm2_private.h
@@ -209,6 +209,8 @@ struct _Ecore_Drm2_Output
    int pipe;
    int x, y, w, h, pw, ph;
 
+   long fallback_sec, fallback_usec;
+
    uint32_t subpixel;
    uint32_t crtc_id, conn_id, conn_type;
    uint32_t scale;