From db1a606610e5a528903a4380f30c9934a0c5a134 Mon Sep 17 00:00:00 2001

From: David Herrmann <dh.herrmann@gmail.com>

Date: Thu, 2 Oct 2014 13:11:53 +0200

Subject: [PATCH] terminal: fix back-buffer selection on DRM page-flip

We currently select front-buffers as new back-buffer if they happen to be

the last buffer in our framebuffer-array. Fix this by never selecting a

new front buffer as back buffer.

---

 src/libsystemd-terminal/grdev-drm.c | 7 +++----

 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/libsystemd-terminal/grdev-drm.c b/src/libsystemd-terminal/grdev-drm.c

index 5393ebf988..7a6e1d993b 100644

--- a/src/libsystemd-terminal/grdev-drm.c

+++ b/src/libsystemd-terminal/grdev-drm.c

@@ -1362,10 +1362,9 @@ static void grdrm_crtc_flip_complete(grdrm_crtc *crtc, uint32_t counter, struct

                 fb = fb_from_base(pipe->base.fbs[i]);

                 if (counter != 0 && counter == pipe->counter && fb->flipid == counter) {

                         pipe->base.front = &fb->base;

+                        fb->flipid = 0;

                         flipped = true;

-                }

-

-                if (counter - fb->flipid < UINT16_MAX) {

+                } else if (counter - fb->flipid < UINT16_MAX) {

                         fb->flipid = 0;

                         back = fb;

                 } else if (fb->flipid == 0) {

@@ -1373,7 +1372,7 @@ static void grdrm_crtc_flip_complete(grdrm_crtc *crtc, uint32_t counter, struct

                 }

         }

-        if (!pipe->base.back)

+        if (!pipe->base.back && back)

                 pipe->base.back = &back->base;

         if (flipped) {