Bug 80349

Summary:	[Regression][Bisected] Choppy fullscreen using OpenGL with compositor
Product:	xorg	Reporter:	ValdikSS <iam>
Component:	Driver/intel	Assignee:	Chris Wilson <chris>
Status:	RESOLVED NOTOURBUG	QA Contact:	Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity:	normal
Priority:	medium	CC:	luiorpe1
Version:	unspecified
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:

Description ValdikSS 2014-06-22 09:14:09 UTC

OpenGL in fullscreen is choppy since:

commit 8369166349c92a20d9a2e7d0256e63f66fe2682b
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Wed Jun 4 08:29:51 2014 +0100

    sna/dri2: Enable immediate buffer exchanges
    
    The primary benefit of this is avoid the extra blit when using a
    compositor and instead propagate the compositor flip on the frontbuffer
    to the scanout, or equivalently allows a fullscreen game to flip onto
    the scanout without intervention by TearFree.
    
    Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

How to reproduce:
1. Download http://rghost.ru/56512098. This is 60 fps video
2. mplayer -vo gl output.mp4 or mpv --vo opengl output.mp4
3. Watch video in windowed mode. It should play very smooth
4. Run mplayer/mpv again. Press "f" to go fullscreen

Expected result:
Video in fullscreen is as smooth as in windowed mode

Actual result:
Video is choppy

Additional information:
I'm running ArchLinux with latest KDE and KWin. It happens only with compositing on and does not have any correlation with vsync. I'm not using TearFree driver option.

Comment 1 Chris Wilson 2014-06-22 10:00:18 UTC

Kwin makes a buggy micro-optimisation:

diff --git a/kwin/libkwineffects/kwinglplatform.cpp b/kwin/libkwineffects/kwinglplatform.cpp
index ae2f459..c41b9df 100644
--- a/kwin/libkwineffects/kwinglplatform.cpp
+++ b/kwin/libkwineffects/kwinglplatform.cpp
@@ -808,7 +808,6 @@ void GLPlatform::detect(OpenGLPlatformInterface platformInterface)
             m_supportsGLSL = false;
 
         m_limitedGLSL = m_supportsGLSL && m_chipClass < I965;
-        m_looseBinding = true;
 
         if (m_chipClass < I915) {
             m_recommendedCompositor = XRenderCompositing;

Comment 2 ValdikSS 2014-06-22 17:53:48 UTC

(In reply to comment #1)

Thanks! Filled bug to KDE bugtracker
https://bugs.kde.org/show_bug.cgi?id=336589

Comment 3 Chris Wilson 2014-06-23 22:04:22 UTC

*** Bug 80428 has been marked as a duplicate of this bug. ***

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