drm/nouveau/fifo/nvc0-: use interrupt 31 as an event trigger

Generated if you try and use fifo method 0x20 on any subchannel, appears
that it can be safely masked off without stalling the whole GPU.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/core/engine/fifo/base.c

@@ -25,6 +25,7 @@
 #include <core/client.h>
 #include <core/object.h>
 #include <core/handle.h>
+#include <core/event.h>
 #include <core/class.h>
 
 #include <engine/dmaobj.h>
@@ -165,6 +166,7 @@ void
 nouveau_fifo_destroy(struct nouveau_fifo *priv)
 {
 	kfree(priv->channel);
+	nouveau_event_destroy(&priv->uevent);
 	nouveau_engine_destroy(&priv->base);
 }
 
@@ -189,6 +191,10 @@ nouveau_fifo_create_(struct nouveau_object *parent,
 	if (!priv->channel)
 		return -ENOMEM;
 
+	ret = nouveau_event_create(1, &priv->uevent);
+	if (ret)
+		return ret;
+
 	priv->chid = nouveau_fifo_chid;
 	spin_lock_init(&priv->lock);
 	return 0;

drivers/gpu/drm/nouveau/core/engine/fifo/nvc0.c

@@ -27,6 +27,7 @@
 #include <core/namedb.h>
 #include <core/gpuobj.h>
 #include <core/engctx.h>
+#include <core/event.h>
 #include <core/class.h>
 #include <core/math.h>
 #include <core/enum.h>
@@ -583,7 +584,8 @@ nvc0_fifo_intr(struct nouveau_subdev *subdev)
 
 	if (stat & 0x80000000) {
 		u32 intr = nv_mask(priv, 0x0025a8, 0x00000000, 0x00000000);
-		nv_warn(priv, "INTR 0x80000000: 0x%08x\n", intr);
+		nouveau_event_trigger(priv->base.uevent, 0);
+		nv_debug(priv, "INTR 0x80000000: 0x%08x\n", intr);
 		stat &= ~0x80000000;
 	}
 
@@ -594,6 +596,20 @@ nvc0_fifo_intr(struct nouveau_subdev *subdev)
 	}
 }
 
+static void
+nvc0_fifo_uevent_enable(struct nouveau_event *event, int index)
+{
+	struct nvc0_fifo_priv *priv = event->priv;
+	nv_mask(priv, 0x002140, 0x80000000, 0x80000000);
+}
+
+static void
+nvc0_fifo_uevent_disable(struct nouveau_event *event, int index)
+{
+	struct nvc0_fifo_priv *priv = event->priv;
+	nv_mask(priv, 0x002140, 0x80000000, 0x00000000);
+}
+
 static int
 nvc0_fifo_ctor(struct nouveau_object *parent, struct nouveau_object *engine,
 	       struct nouveau_oclass *oclass, void *data, u32 size,
@@ -627,6 +643,10 @@ nvc0_fifo_ctor(struct nouveau_object *parent, struct nouveau_object *engine,
 	if (ret)
 		return ret;
 
+	priv->base.uevent->enable = nvc0_fifo_uevent_enable;
+	priv->base.uevent->disable = nvc0_fifo_uevent_disable;
+	priv->base.uevent->priv = priv;
+
 	nv_subdev(priv)->unit = 0x00000100;
 	nv_subdev(priv)->intr = nvc0_fifo_intr;
 	nv_engine(priv)->cclass = &nvc0_fifo_cclass;
@@ -685,7 +705,7 @@ nvc0_fifo_init(struct nouveau_object *object)
 
 	nv_wr32(priv, 0x002a00, 0xffffffff); /* clears PFIFO.INTR bit 30 */
 	nv_wr32(priv, 0x002100, 0xffffffff);
-	nv_wr32(priv, 0x002140, 0xbfffffff);
+	nv_wr32(priv, 0x002140, 0x3fffffff);
 	return 0;
 }
 

drivers/gpu/drm/nouveau/core/engine/fifo/nve0.c

@@ -27,6 +27,7 @@
 #include <core/namedb.h>
 #include <core/gpuobj.h>
 #include <core/engctx.h>
+#include <core/event.h>
 #include <core/class.h>
 #include <core/math.h>
 #include <core/enum.h>
@@ -554,6 +555,12 @@ nve0_fifo_intr(struct nouveau_subdev *subdev)
 		stat &= ~0x40000000;
 	}
 
+	if (stat & 0x80000000) {
+		nouveau_event_trigger(priv->base.uevent, 0);
+		nv_wr32(priv, 0x002100, 0x80000000);
+		stat &= ~0x80000000;
+	}
+
 	if (stat) {
 		nv_fatal(priv, "unhandled status 0x%08x\n", stat);
 		nv_wr32(priv, 0x002100, stat);
@@ -561,6 +568,20 @@ nve0_fifo_intr(struct nouveau_subdev *subdev)
 	}
 }
 
+static void
+nve0_fifo_uevent_enable(struct nouveau_event *event, int index)
+{
+	struct nve0_fifo_priv *priv = event->priv;
+	nv_mask(priv, 0x002140, 0x80000000, 0x80000000);
+}
+
+static void
+nve0_fifo_uevent_disable(struct nouveau_event *event, int index)
+{
+	struct nve0_fifo_priv *priv = event->priv;
+	nv_mask(priv, 0x002140, 0x80000000, 0x00000000);
+}
+
 static int
 nve0_fifo_ctor(struct nouveau_object *parent, struct nouveau_object *engine,
 	       struct nouveau_oclass *oclass, void *data, u32 size,
@@ -584,6 +605,10 @@ nve0_fifo_ctor(struct nouveau_object *parent, struct nouveau_object *engine,
 	if (ret)
 		return ret;
 
+	priv->base.uevent->enable = nve0_fifo_uevent_enable;
+	priv->base.uevent->disable = nve0_fifo_uevent_disable;
+	priv->base.uevent->priv = priv;
+
 	nv_subdev(priv)->unit = 0x00000100;
 	nv_subdev(priv)->intr = nve0_fifo_intr;
 	nv_engine(priv)->cclass = &nve0_fifo_cclass;
@@ -634,7 +659,7 @@ nve0_fifo_init(struct nouveau_object *object)
 
 	nv_wr32(priv, 0x002a00, 0xffffffff);
 	nv_wr32(priv, 0x002100, 0xffffffff);
-	nv_wr32(priv, 0x002140, 0xbfffffff);
+	nv_wr32(priv, 0x002140, 0x3fffffff);
 	return 0;
 }
 

drivers/gpu/drm/nouveau/core/include/engine/fifo.h

@@ -65,6 +65,8 @@ struct nouveau_fifo_base {
 struct nouveau_fifo {
 	struct nouveau_engine base;
 
+	struct nouveau_event *uevent;
+
 	struct nouveau_object **channel;
 	spinlock_t lock;
 	u16 min;