6 files changed, 49 insertions, 18 deletions

diff --git a/drivers/gpu/drm/virtio/Kconfig b/drivers/gpu/drm/virtio/Kconfig
index 51ec7c3240c9..ea06ff2aa4b4 100644
--- a/drivers/gpu/drm/virtio/Kconfig
+++ b/drivers/gpu/drm/virtio/Kconfig
@@ -11,3 +11,14 @@ config DRM_VIRTIO_GPU
 	   QEMU based VMMs (like KVM or Xen).
 
 	   If unsure say M.
+
+config DRM_VIRTIO_GPU_KMS
+	bool "Virtio GPU driver modesetting support"
+	depends on DRM_VIRTIO_GPU
+	default y
+	help
+	   Enable modesetting support for virtio GPU driver.  This can be
+	   disabled in cases where only "headless" usage of the GPU is
+	   required.
+
+	   If unsure, say Y.
diff --git a/drivers/gpu/drm/virtio/virtgpu_display.c b/drivers/gpu/drm/virtio/virtgpu_display.c
index 9ea7611a9e0f..ad924a8502e9 100644
--- a/drivers/gpu/drm/virtio/virtgpu_display.c
+++ b/drivers/gpu/drm/virtio/virtgpu_display.c
@@ -336,6 +336,9 @@ int virtio_gpu_modeset_init(struct virtio_gpu_device *vgdev)
 {
 	int i, ret;
 
+	if (!vgdev->num_scanouts)
+		return 0;
+
 	ret = drmm_mode_config_init(vgdev->ddev);
 	if (ret)
 		return ret;
@@ -362,6 +365,9 @@ void virtio_gpu_modeset_fini(struct virtio_gpu_device *vgdev)
 {
 	int i;
 
+	if (!vgdev->num_scanouts)
+		return;
+
 	for (i = 0 ; i < vgdev->num_scanouts; ++i)
 		kfree(vgdev->outputs[i].edid);
 }
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c b/drivers/gpu/drm/virtio/virtgpu_drv.c
index ae97b98750b6..add075681e18 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.c
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
@@ -172,6 +172,10 @@ MODULE_AUTHOR("Alon Levy");
 DEFINE_DRM_GEM_FOPS(virtio_gpu_driver_fops);
 
 static const struct drm_driver driver = {
+	/*
+	 * If KMS is disabled DRIVER_MODESET and DRIVER_ATOMIC are masked
+	 * out via drm_device::driver_features:
+	 */
 	.driver_features = DRIVER_MODESET | DRIVER_GEM | DRIVER_RENDER | DRIVER_ATOMIC,
 	.open = virtio_gpu_driver_open,
 	.postclose = virtio_gpu_driver_postclose,
diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/virtio/virtgpu_kms.c
index 27b7f14dae89..5a3b5aaed1f3 100644
--- a/drivers/gpu/drm/virtio/virtgpu_kms.c
+++ b/drivers/gpu/drm/virtio/virtgpu_kms.c
@@ -43,11 +43,13 @@ static void virtio_gpu_config_changed_work_func(struct work_struct *work)
 	virtio_cread_le(vgdev->vdev, struct virtio_gpu_config,
 			events_read, &events_read);
 	if (events_read & VIRTIO_GPU_EVENT_DISPLAY) {
-		if (vgdev->has_edid)
-			virtio_gpu_cmd_get_edids(vgdev);
-		virtio_gpu_cmd_get_display_info(vgdev);
-		virtio_gpu_notify(vgdev);
-		drm_helper_hpd_irq_event(vgdev->ddev);
+		if (vgdev->num_scanouts) {
+			if (vgdev->has_edid)
+				virtio_gpu_cmd_get_edids(vgdev);
+			virtio_gpu_cmd_get_display_info(vgdev);
+			virtio_gpu_notify(vgdev);
+			drm_helper_hpd_irq_event(vgdev->ddev);
+		}
 		events_clear |= VIRTIO_GPU_EVENT_DISPLAY;
 	}
 	virtio_cwrite_le(vgdev->vdev, struct virtio_gpu_config,
@@ -223,12 +225,15 @@ int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev)
 			num_scanouts, &num_scanouts);
 	vgdev->num_scanouts = min_t(uint32_t, num_scanouts,
 				    VIRTIO_GPU_MAX_SCANOUTS);
-	if (!vgdev->num_scanouts) {
-		DRM_ERROR("num_scanouts is zero\n");
-		ret = -EINVAL;
-		goto err_scanouts;
+
+	if (!IS_ENABLED(CONFIG_DRM_VIRTIO_GPU_KMS) || !vgdev->num_scanouts) {
+		DRM_INFO("KMS disabled\n");
+		vgdev->num_scanouts = 0;
+		vgdev->has_edid = false;
+		dev->driver_features &= ~(DRIVER_MODESET | DRIVER_ATOMIC);
+	} else {
+		DRM_INFO("number of scanouts: %d\n", num_scanouts);
 	}
-	DRM_INFO("number of scanouts: %d\n", num_scanouts);
 
 	virtio_cread_le(vgdev->vdev, struct virtio_gpu_config,
 			num_capsets, &num_capsets);
@@ -244,12 +249,14 @@ int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev)
 
 	if (num_capsets)
 		virtio_gpu_get_capsets(vgdev, num_capsets);
-	if (vgdev->has_edid)
-		virtio_gpu_cmd_get_edids(vgdev);
-	virtio_gpu_cmd_get_display_info(vgdev);
-	virtio_gpu_notify(vgdev);
-	wait_event_timeout(vgdev->resp_wq, !vgdev->display_info_pending,
-			   5 * HZ);
+	if (vgdev->num_scanouts) {
+		if (vgdev->has_edid)
+			virtio_gpu_cmd_get_edids(vgdev);
+		virtio_gpu_cmd_get_display_info(vgdev);
+		virtio_gpu_notify(vgdev);
+		wait_event_timeout(vgdev->resp_wq, !vgdev->display_info_pending,
+				   5 * HZ);
+	}
 	return 0;
 
 err_scanouts:
diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c b/drivers/gpu/drm/virtio/virtgpu_plane.c
index 4c09e313bebc..a2e045f3a000 100644
--- a/drivers/gpu/drm/virtio/virtgpu_plane.c
+++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
@@ -390,5 +390,9 @@ struct drm_plane *virtio_gpu_plane_init(struct virtio_gpu_device *vgdev,
 		return plane;
 
 	drm_plane_helper_add(plane, funcs);
+
+	if (type == DRM_PLANE_TYPE_PRIMARY)
+		drm_plane_enable_fb_damage_clips(plane);
+
 	return plane;
 }
diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 1778a2081fd6..b1a00c0c25a7 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -923,8 +923,7 @@ void virtio_gpu_cmd_context_create(struct virtio_gpu_device *vgdev, uint32_t id,
 	cmd_p->hdr.ctx_id = cpu_to_le32(id);
 	cmd_p->nlen = cpu_to_le32(nlen);
 	cmd_p->context_init = cpu_to_le32(context_init);
-	strncpy(cmd_p->debug_name, name, sizeof(cmd_p->debug_name) - 1);
-	cmd_p->debug_name[sizeof(cmd_p->debug_name) - 1] = 0;
+	strscpy(cmd_p->debug_name, name, sizeof(cmd_p->debug_name));
 	virtio_gpu_queue_ctrl_buffer(vgdev, vbuf);
 }