From ab878118b9fb46c437a02f824d29f4a206e7fd80 Mon Sep 17 00:00:00 2001
From: Eric Anholt <eric@anholt.net>
Date: Mon, 27 Apr 2009 16:00:05 -0700
Subject: Don't initialize DRI2 if the fd we get is not master-capable.

---
 src/i830_dri.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/i830_dri.c b/src/i830_dri.c
index 70b76aed..93bb3409 100644
--- a/src/i830_dri.c
+++ b/src/i830_dri.c
@@ -1829,8 +1829,22 @@ Bool I830DRI2ScreenInit(ScreenPtr pScreen)
 	info.fd = pI830->drmSubFD;
 #endif
 
-    if (info.fd < 0)
+    if (info.fd < 0) {
 	info.fd = drmOpen("i915", buf);
+	drmSetVersion sv;
+	int err;
+
+	/* Check that what we opened was a master or a master-capable FD,
+	 * by setting the version of the interface we'll use to talk to it.
+	 * (see DRIOpenDRMMaster() in DRI1)
+	 */
+	sv.drm_di_major = 1;
+	sv.drm_di_minor = 1;
+	sv.drm_dd_major = -1;
+	err = drmSetInterfaceVersion(info.fd, &sv);
+	if (err != 0)
+	    return FALSE;
+    }
 
     if (info.fd < 0) {
 	xf86DrvMsg(pScrn->scrnIndex, X_WARNING, "Failed to open DRM device\n");
-- 
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