From 857f4de8a8fc14a0bce566baf07b0eedc1b6b5b5 Mon Sep 17 00:00:00 2001
From: Lukasz Spintzyk <lukasz.spintzyk@synaptics.com>
Date: Mon, 19 Jul 2021 08:17:09 +0200
Subject: [PATCH xserver] present: get_crtc should not return crtc when its
 screen does not have present extension

Since crtc can belong to secondary output that may not have present
extension enabled we should fallback to first enabled crtc or fake crtc.

Fix for issue xorg/xserver#1195
---
 present/present.c | 11 ++++++++++-
 randr/randr.c     | 27 +++++++++++++++++++++++++++
 randr/randrstr.h  |  2 ++
 3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/present/present.c b/present/present.c
index 3eddb7434..66411212b 100644
--- a/present/present.c
+++ b/present/present.c
@@ -59,11 +59,20 @@ present_get_crtc(WindowPtr window)
 {
     ScreenPtr                   screen = window->drawable.pScreen;
     present_screen_priv_ptr     screen_priv = present_screen_priv(screen);
+    RRCrtcPtr                   crtc = NULL;
+    RROutputPtr                 firstOutput = NULL;
 
     if (!screen_priv)
         return NULL;
 
-    return screen_priv->get_crtc(screen_priv, window);
+    crtc = screen_priv->get_crtc(screen_priv, window);
+    if (crtc && !present_screen_priv(crtc->pScreen)) {
+        crtc = RRFirstEnabledCrtc(screen);
+    }
+    if (crtc && !present_screen_priv(crtc->pScreen)) {
+        crtc = NULL;
+    }
+    return crtc;
 }
 
 /*
diff --git a/randr/randr.c b/randr/randr.c
index 5db8b5ced..afc867ea9 100644
--- a/randr/randr.c
+++ b/randr/randr.c
@@ -693,6 +693,33 @@ RRFirstOutput(ScreenPtr pScreen)
     return NULL;
 }
 
+RRCrtcPtr
+RRFirstEnabledCrtc(ScreenPtr pScreen)
+{
+    rrScrPriv(pScreen);
+    RROutputPtr output;
+    int i, j;
+
+    if (!pScrPriv)
+        return NULL;
+
+    if (pScrPriv->primaryOutput && pScrPriv->primaryOutput->crtc &&
+        pScrPriv->primaryOutput->pScreen == pScreen)
+        return pScrPriv->primaryOutput->crtc;
+
+    for (i = 0; i < pScrPriv->numCrtcs; i++) {
+        RRCrtcPtr crtc = pScrPriv->crtcs[i];
+
+        for (j = 0; j < pScrPriv->numOutputs; j++) {
+            output = pScrPriv->outputs[j];
+            if (output->crtc == crtc && crtc->mode)
+                return crtc;
+        }
+    }
+    return NULL;
+}
+
+
 CARD16
 RRVerticalRefresh(xRRModeInfo * mode)
 {
diff --git a/randr/randrstr.h b/randr/randrstr.h
index 0b95d6e25..28ba4ea91 100644
--- a/randr/randrstr.h
+++ b/randr/randrstr.h
@@ -593,6 +593,8 @@ extern _X_EXPORT Bool RRScreenInit(ScreenPtr pScreen);
 
 extern _X_EXPORT RROutputPtr RRFirstOutput(ScreenPtr pScreen);
 
+extern _X_EXPORT RRCrtcPtr RRFirstEnabledCrtc(ScreenPtr pScreen);
+
 extern _X_EXPORT Bool RROutputSetNonDesktop(RROutputPtr output, Bool non_desktop);
 
 extern _X_EXPORT CARD16
-- 
2.30.2