Disable dri2 after forcing fallbacks

If we force fallbacks, then we will only create pixmaps in system
memory, preventing DRI2 from passing valid bo names to the clients. In
this case, they will just fallback to swrast. If we disable DRI2 after
forcing fallbacks (e.g. regenerating after a GPU hang or explicitly
disabled with the shadow buffer) then it is simpler just to disable the
extension and allow mesa to use pure swrast.

Reported-by: Julien Cristau <jcristau@debian.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

2 files changed, 60 insertions, 53 deletions

diff --git a/src/intel_dri.c b/src/intel_dri.c
index 4f669372..98042722 100644
--- a/src/intel_dri.c
+++ b/src/intel_dri.c
@@ -1029,6 +1029,12 @@ Bool I830DRI2ScreenInit(ScreenPtr screen)
 	const char *driverNames[1];
 #endif
 
+	if (intel->force_fallback) {
+		xf86DrvMsg(scrn->scrnIndex, X_WARNING,
+			   "cannot enable DRI2 whilst forcing software fallbacks\n");
+		return FALSE;
+	}
+
 	if (xf86LoaderCheckSymbol("DRI2Version"))
 		DRI2Version(&dri2_major, &dri2_minor);
 
diff --git a/src/intel_driver.c b/src/intel_driver.c
index c0ad69e9..d086d941 100644
--- a/src/intel_driver.c
+++ b/src/intel_driver.c
@@ -588,13 +588,59 @@ static Bool I830PreInit(ScrnInfoPtr scrn, int flags)
 	intel_check_chipset_option(scrn);
 	intel_check_dri_option(scrn);
 
-	I830XvInit(scrn);
-
 	if (!intel_init_bufmgr(intel)) {
 		PreInitCleanup(scrn);
 		return FALSE;
 	}
 
+	intel->force_fallback =
+		drmCommandNone(intel->drmSubFD, DRM_I915_GEM_THROTTLE) != 0;
+	intel->use_shadow = FALSE;
+
+	/* Enable tiling by default */
+	intel->tiling = TRUE;
+
+	/* Allow user override if they set a value */
+	if (xf86IsOptionSet(intel->Options, OPTION_TILING)) {
+		if (xf86ReturnOptValBool(intel->Options, OPTION_TILING, FALSE))
+			intel->tiling = TRUE;
+		else
+			intel->tiling = FALSE;
+	}
+
+	if (xf86IsOptionSet(intel->Options, OPTION_SHADOW)) {
+		if (xf86ReturnOptValBool(intel->Options, OPTION_SHADOW, FALSE))
+			intel->force_fallback = intel->use_shadow = TRUE;
+	}
+
+	if (intel->use_shadow) {
+		xf86DrvMsg(scrn->scrnIndex, X_CONFIG,
+			   "Shadow buffer enabled,"
+			   " GPU acceleration disabled.\n");
+	}
+
+	/* SwapBuffers delays to avoid tearing */
+	intel->swapbuffers_wait = TRUE;
+
+	/* Allow user override if they set a value */
+	if (xf86IsOptionSet(intel->Options, OPTION_SWAPBUFFERS_WAIT)) {
+		if (xf86ReturnOptValBool
+		    (intel->Options, OPTION_SWAPBUFFERS_WAIT, FALSE))
+			intel->swapbuffers_wait = TRUE;
+		else
+			intel->swapbuffers_wait = FALSE;
+	}
+
+	if (IS_GEN6(intel))
+	    intel->swapbuffers_wait = FALSE;
+
+	xf86DrvMsg(scrn->scrnIndex, X_CONFIG, "Tiling %sabled\n",
+		   intel->tiling ? "en" : "dis");
+	xf86DrvMsg(scrn->scrnIndex, X_CONFIG, "SwapBuffers wait %sabled\n",
+		   intel->swapbuffers_wait ? "en" : "dis");
+
+	I830XvInit(scrn);
+
 	if (!intel_mode_pre_init(scrn, intel->drmSubFD, intel->cpp)) {
 		PreInitCleanup(scrn);
 		return FALSE;
@@ -830,57 +876,6 @@ I830ScreenInit(int scrnIndex, ScreenPtr screen, int argc, char **argv)
 
 	scrn->videoRam = device->regions[fb_bar].size / 1024;
 
-#ifdef DRI2
-	if (intel->directRenderingType == DRI_NONE
-	    && I830DRI2ScreenInit(screen))
-		intel->directRenderingType = DRI_DRI2;
-#endif
-
-	intel->force_fallback = FALSE;
-	intel->use_shadow = FALSE;
-
-	/* Enable tiling by default */
-	intel->tiling = TRUE;
-
-	/* Allow user override if they set a value */
-	if (xf86IsOptionSet(intel->Options, OPTION_TILING)) {
-		if (xf86ReturnOptValBool(intel->Options, OPTION_TILING, FALSE))
-			intel->tiling = TRUE;
-		else
-			intel->tiling = FALSE;
-	}
-
-	if (xf86IsOptionSet(intel->Options, OPTION_SHADOW)) {
-		if (xf86ReturnOptValBool(intel->Options, OPTION_SHADOW, FALSE))
-			intel->force_fallback = intel->use_shadow = TRUE;
-	}
-
-	if (intel->use_shadow) {
-		xf86DrvMsg(scrn->scrnIndex, X_CONFIG,
-			   "Shadow buffer enabled,"
-			   " GPU acceleration disabled.\n");
-	}
-
-	/* SwapBuffers delays to avoid tearing */
-	intel->swapbuffers_wait = TRUE;
-
-	/* Allow user override if they set a value */
-	if (xf86IsOptionSet(intel->Options, OPTION_SWAPBUFFERS_WAIT)) {
-		if (xf86ReturnOptValBool
-		    (intel->Options, OPTION_SWAPBUFFERS_WAIT, FALSE))
-			intel->swapbuffers_wait = TRUE;
-		else
-			intel->swapbuffers_wait = FALSE;
-	}
-
-	if (IS_GEN6(intel))
-	    intel->swapbuffers_wait = FALSE;
-
-	xf86DrvMsg(scrn->scrnIndex, X_CONFIG, "Tiling %sabled\n",
-		   intel->tiling ? "en" : "dis");
-	xf86DrvMsg(scrn->scrnIndex, X_CONFIG, "SwapBuffers wait %sabled\n",
-		   intel->swapbuffers_wait ? "en" : "dis");
-
 	intel->last_3d = LAST_3D_OTHER;
 	intel->overlayOn = FALSE;
 
@@ -894,6 +889,12 @@ I830ScreenInit(int scrnIndex, ScreenPtr screen, int argc, char **argv)
 		   intel->pEnt->device->videoRam ? X_CONFIG : X_DEFAULT,
 		   "VideoRam: %d KB\n", scrn->videoRam);
 
+#ifdef DRI2
+	if (intel->directRenderingType == DRI_NONE
+	    && I830DRI2ScreenInit(screen))
+		intel->directRenderingType = DRI_DRI2;
+#endif
+
 	if (!intel_init_initial_framebuffer(scrn))
 		return FALSE;