drm/nv50: punt hotplug irq handling out to workqueue

On DP outputs we'll likely end up running vbios init tables here, which
may sleep.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_drv.h

@@ -520,6 +520,7 @@ struct drm_nouveau_private {
 
 	struct workqueue_struct *wq;
 	struct work_struct irq_work;
+	struct work_struct hpd_work;
 
 	struct list_head vbl_waiting;
 

drivers/gpu/drm/nouveau/nouveau_irq.c

@@ -51,6 +51,7 @@ nouveau_irq_preinstall(struct drm_device *dev)
 
 	if (dev_priv->card_type == NV_50) {
 		INIT_WORK(&dev_priv->irq_work, nv50_display_irq_handler_bh);
+		INIT_WORK(&dev_priv->hpd_work, nv50_display_irq_hotplug_bh);
 		INIT_LIST_HEAD(&dev_priv->vbl_waiting);
 	}
 }

drivers/gpu/drm/nouveau/nv50_display.c

@@ -887,10 +887,12 @@ nv50_display_error_handler(struct drm_device *dev)
 	nv_wr32(dev, NV50_PDISPLAY_TRAPPED_ADDR, 0x90000000);
 }
 
-static void
-nv50_display_irq_hotplug(struct drm_device *dev)
+void
+nv50_display_irq_hotplug_bh(struct work_struct *work)
 {
-	struct drm_nouveau_private *dev_priv = dev->dev_private;
+	struct drm_nouveau_private *dev_priv =
+		container_of(work, struct drm_nouveau_private, hpd_work);
+	struct drm_device *dev = dev_priv->dev;
 	struct drm_connector *connector;
 	const uint32_t gpio_reg[4] = { 0xe104, 0xe108, 0xe280, 0xe284 };
 	uint32_t unplug_mask, plug_mask, change_mask;
@@ -951,8 +953,10 @@ nv50_display_irq_handler(struct drm_device *dev)
 	struct drm_nouveau_private *dev_priv = dev->dev_private;
 	uint32_t delayed = 0;
 
-	while (nv_rd32(dev, NV50_PMC_INTR_0) & NV50_PMC_INTR_0_HOTPLUG)
-		nv50_display_irq_hotplug(dev);
+	if (nv_rd32(dev, NV50_PMC_INTR_0) & NV50_PMC_INTR_0_HOTPLUG) {
+		if (!work_pending(&dev_priv->hpd_work))
+			queue_work(dev_priv->wq, &dev_priv->hpd_work);
+	}
 
 	while (nv_rd32(dev, NV50_PMC_INTR_0) & NV50_PMC_INTR_0_DISPLAY) {
 		uint32_t intr0 = nv_rd32(dev, NV50_PDISPLAY_INTR_0);

drivers/gpu/drm/nouveau/nv50_display.h

@@ -37,6 +37,7 @@
 
 void nv50_display_irq_handler(struct drm_device *dev);
 void nv50_display_irq_handler_bh(struct work_struct *work);
+void nv50_display_irq_hotplug_bh(struct work_struct *work);
 int nv50_display_init(struct drm_device *dev);
 int nv50_display_create(struct drm_device *dev);
 int nv50_display_destroy(struct drm_device *dev);