From 68a8963f726cb92624665669813b6d952d53556e Mon Sep 17 00:00:00 2001
From: Luc Verhaegen <libv@skynet.be>
Date: Tue, 7 Mar 2006 16:00:57 +0000
Subject: [PATCH] Fix cvt -r check again. CH7011 TV encoder had 800x600 PAL hit
 the check.

---
 ChangeLog                    | 17 +++++++++++++++++
 hw/xfree86/common/xf86Mode.c | 31 ++++++++++++++++++-------------
 2 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 2c99ae9d8..6472095fc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,20 @@
+2006-03-07  Luc Verhaegen  <libv@skynet.be>
+
+	* hw/xfree86/common/xf86Mode.c: (xf86CheckModeForMonitor):
+	Third pass at stopping reduced blanking modes for CRTs. This time
+	round, there is almost no room for error left. We stop modes only
+	when:
+	- Hblank is less than 25% of HDisplay and
+	- HTotal - HDisplay is exactly 160 and
+	- HSyncEnd - HDisplay is exactly 80 (new) and  
+	- HSyncEnd - HSyncStart is exactly 32 (new) and
+	- VSyncStart - VDisplay is exactly 3 (new).
+	So, we stop antique monitors which are rumoured to blow up regularly
+	from doing so _only_ with modes generated by xf86CVTMode with Reduced
+	TRUE or modelines generated by cvt -r. If the user dares as much as
+	look at such a modeline, we're free to scorch off his face and fill it
+	with glass.
+
 2006-03-06  Lars Knoll <lars@trolltech.com>
 
 	* render/picture.c
diff --git a/hw/xfree86/common/xf86Mode.c b/hw/xfree86/common/xf86Mode.c
index bb8f4b1d1..c84d952f0 100644
--- a/hw/xfree86/common/xf86Mode.c
+++ b/hw/xfree86/common/xf86Mode.c
@@ -1,4 +1,4 @@
-/* $XdotOrg: xserver/xorg/hw/xfree86/common/xf86Mode.c,v 1.8 2005/12/28 15:22:21 libv Exp $ */
+/* $XdotOrg: xserver/xorg/hw/xfree86/common/xf86Mode.c,v 1.9 2006/01/31 13:04:02 libv Exp $ */
 /* $XFree86: xc/programs/Xserver/hw/xfree86/common/xf86Mode.c,v 1.69 2003/10/08 14:58:28 dawes Exp $ */
 /*
  * Copyright (c) 1997-2003 by The XFree86 Project, Inc.
@@ -817,19 +817,24 @@ xf86CheckModeForMonitor(DisplayModePtr mode, MonPtr monitor)
 	mode->CrtcVTotal = mode->VTotal |= 1;
 
     /*
-     * Usually, CVT normal blanking is never more than one character below 25%,
-     * but for low frequencies and weird ratios, you can get below that.
-     * When you go into the low frequencies with the gtf generator, of which
-     * normal CVT is a simplification, you almost always go below 25%.
-     *
-     * So if we see awkward blanking, then it's either directly CVT or GTF
-     * generated, or the user supposedly knows what he's doing. So we only stop
-     * reduced blanking here, as that might accidentally hit us. -- libv
+     * This code stops cvt -r modes, and only cvt -r modes, from hitting 15y+
+     * old CRTs which might, when there is a lot of solar flare activity and
+     * when the celestial bodies are unfavourably aligned, implode trying to
+     * sync to it. It's called "Protecting the user from doing anything stupid".
+     * -- libv
      */
-    if (((mode->HTotal - mode->HDisplay) == 160) &&
-        (((mode->HDisplay * 5 / 4) & ~0x07) > mode->HTotal))
-        if (!monitor->reducedblanking)
-            return MODE_NO_REDUCED;
+
+    /* Is the horizontal blanking a bit lowish? */
+    if (((mode->HDisplay * 5 / 4) & ~0x07) > mode->HTotal) {
+        /* is this a cvt -r mode, and only a cvt -r mode? */
+        if (((mode->HTotal - mode->HDisplay) == 160) &&
+            ((mode->HSyncEnd - mode->HDisplay) == 80) &&
+            ((mode->HSyncEnd - mode->HSyncStart) == 32) &&
+            ((mode->VSyncStart - mode->VDisplay) == 3)) {
+            if (!monitor->reducedblanking)
+                return MODE_NO_REDUCED;
+        }
+    }
 
     return MODE_OK;
 }