[PATCH v2] drm/virtio: rework batching

From: Gerd Hoffmann
Date: Wed Feb 12 2020 - 06:13:03 EST


Drop the virtio_gpu_{disable,enable}_notify(). Add a new
virtio_gpu_notify() call instead, which must be called whenever
the driver wants make sure the host is notified needed.

Drop notification from command submission. Add virtio_gpu_notify()
calls everywhere instead. This results in more batching because we now
notify only once for a series of commands. We already had that for page
flips, now we also batch resource creation (create + attach-backing),
display updates (edid + display-info) and device initialization. With
this in place it is also possible to make notification optional for
userspace ioctls.

v2:
- rebase to latest drm-misc-next.
- use "if (!atomic_read())".
- add review & test tags.

Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Reviewed-by: Gurchetan Singh <gurchetansingh@xxxxxxxxxxxx>
Tested-by: Gurchetan Singh <gurchetansingh@xxxxxxxxxxxx>
---
drivers/gpu/drm/virtio/virtgpu_drv.h | 6 ++---
drivers/gpu/drm/virtio/virtgpu_display.c | 2 ++
drivers/gpu/drm/virtio/virtgpu_ioctl.c | 4 ++++
drivers/gpu/drm/virtio/virtgpu_kms.c | 3 +++
drivers/gpu/drm/virtio/virtgpu_object.c | 1 +
drivers/gpu/drm/virtio/virtgpu_plane.c | 5 ++--
drivers/gpu/drm/virtio/virtgpu_vq.c | 30 ++++++++++--------------
7 files changed, 26 insertions(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index af9403e1cf78..2f6c4ccbfd14 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -179,8 +179,7 @@ struct virtio_gpu_device {
struct virtio_gpu_queue cursorq;
struct kmem_cache *vbufs;

- bool disable_notify;
- bool pending_notify;
+ atomic_t pending_commands;

struct ida resource_ida;

@@ -335,8 +334,7 @@ void virtio_gpu_dequeue_ctrl_func(struct work_struct *work);
void virtio_gpu_dequeue_cursor_func(struct work_struct *work);
void virtio_gpu_dequeue_fence_func(struct work_struct *work);

-void virtio_gpu_disable_notify(struct virtio_gpu_device *vgdev);
-void virtio_gpu_enable_notify(struct virtio_gpu_device *vgdev);
+void virtio_gpu_notify(struct virtio_gpu_device *vgdev);

/* virtio_gpu_display.c */
void virtio_gpu_modeset_init(struct virtio_gpu_device *vgdev);
diff --git a/drivers/gpu/drm/virtio/virtgpu_display.c b/drivers/gpu/drm/virtio/virtgpu_display.c
index af953db4a0c9..2b7e6ae65546 100644
--- a/drivers/gpu/drm/virtio/virtgpu_display.c
+++ b/drivers/gpu/drm/virtio/virtgpu_display.c
@@ -90,6 +90,7 @@ static void virtio_gpu_crtc_mode_set_nofb(struct drm_crtc *crtc)
virtio_gpu_cmd_set_scanout(vgdev, output->index, 0,
crtc->mode.hdisplay,
crtc->mode.vdisplay, 0, 0);
+ virtio_gpu_notify(vgdev);
}

static void virtio_gpu_crtc_atomic_enable(struct drm_crtc *crtc,
@@ -108,6 +109,7 @@ static void virtio_gpu_crtc_atomic_disable(struct drm_crtc *crtc,
struct virtio_gpu_output *output = drm_crtc_to_virtio_gpu_output(crtc);

virtio_gpu_cmd_set_scanout(vgdev, output->index, 0, 0, 0, 0, 0);
+ virtio_gpu_notify(vgdev);
output->enabled = false;
}

diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index 205ec4abae2b..75d818d707e6 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -158,6 +158,7 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,

virtio_gpu_cmd_submit(vgdev, buf, exbuf->size,
vfpriv->ctx_id, buflist, out_fence);
+ virtio_gpu_notify(vgdev);
return 0;

out_memdup:
@@ -314,6 +315,7 @@ static int virtio_gpu_transfer_from_host_ioctl(struct drm_device *dev,
(vgdev, vfpriv->ctx_id, offset, args->level,
&args->box, objs, fence);
dma_fence_put(&fence->f);
+ virtio_gpu_notify(vgdev);
return 0;

err_unlock:
@@ -359,6 +361,7 @@ static int virtio_gpu_transfer_to_host_ioctl(struct drm_device *dev, void *data,
args->level, &args->box, objs, fence);
dma_fence_put(&fence->f);
}
+ virtio_gpu_notify(vgdev);
return 0;

err_unlock:
@@ -445,6 +448,7 @@ static int virtio_gpu_get_caps_ioctl(struct drm_device *dev,
/* not in cache - need to talk to hw */
virtio_gpu_cmd_get_capset(vgdev, found_valid, args->cap_set_ver,
&cache_ent);
+ virtio_gpu_notify(vgdev);

copy_exit:
ret = wait_event_timeout(vgdev->resp_wq,
diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/virtio/virtgpu_kms.c
index 4009c2f97d08..7eabcf1ca424 100644
--- a/drivers/gpu/drm/virtio/virtgpu_kms.c
+++ b/drivers/gpu/drm/virtio/virtgpu_kms.c
@@ -44,6 +44,7 @@ static void virtio_gpu_config_changed_work_func(struct work_struct *work)
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;
}
@@ -92,6 +93,7 @@ static void virtio_gpu_get_capsets(struct virtio_gpu_device *vgdev,
}
for (i = 0; i < num_capsets; i++) {
virtio_gpu_cmd_get_capset_info(vgdev, i);
+ virtio_gpu_notify(vgdev);
ret = wait_event_timeout(vgdev->resp_wq,
vgdev->capsets[i].id > 0, 5 * HZ);
if (ret == 0) {
@@ -205,6 +207,7 @@ int virtio_gpu_init(struct drm_device *dev)
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;
diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c b/drivers/gpu/drm/virtio/virtgpu_object.c
index 8870ee23ff2b..65d6834d3c74 100644
--- a/drivers/gpu/drm/virtio/virtgpu_object.c
+++ b/drivers/gpu/drm/virtio/virtgpu_object.c
@@ -224,6 +224,7 @@ int virtio_gpu_object_create(struct virtio_gpu_device *vgdev,
return ret;
}

+ virtio_gpu_notify(vgdev);
*bo_ptr = bo;
return 0;

diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c b/drivers/gpu/drm/virtio/virtgpu_plane.c
index ac42c84d2d7f..fd6487fb0855 100644
--- a/drivers/gpu/drm/virtio/virtgpu_plane.c
+++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
@@ -154,8 +154,6 @@ static void virtio_gpu_primary_plane_update(struct drm_plane *plane,
if (!drm_atomic_helper_damage_merged(old_state, plane->state, &rect))
return;

- virtio_gpu_disable_notify(vgdev);
-
bo = gem_to_virtio_gpu_obj(plane->state->fb->obj[0]);
if (bo->dumb)
virtio_gpu_update_dumb_bo(vgdev, plane->state, &rect);
@@ -187,7 +185,7 @@ static void virtio_gpu_primary_plane_update(struct drm_plane *plane,
rect.x2 - rect.x1,
rect.y2 - rect.y1);

- virtio_gpu_enable_notify(vgdev);
+ virtio_gpu_notify(vgdev);
}

static int virtio_gpu_cursor_prepare_fb(struct drm_plane *plane,
@@ -265,6 +263,7 @@ static void virtio_gpu_cursor_plane_update(struct drm_plane *plane,
plane->state->crtc_w,
plane->state->crtc_h,
0, 0, objs, vgfb->fence);
+ virtio_gpu_notify(vgdev);
dma_fence_wait(&vgfb->fence->f, true);
dma_fence_put(&vgfb->fence->f);
vgfb->fence = NULL;
diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index cfe9c54f87a3..357fef8197dc 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -329,7 +329,6 @@ static void virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev,
int incnt)
{
struct virtqueue *vq = vgdev->ctrlq.vq;
- bool notify = false;
int ret, idx;

if (!drm_dev_enter(vgdev->ddev, &idx)) {
@@ -368,16 +367,10 @@ static void virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev,

trace_virtio_gpu_cmd_queue(vq, virtio_gpu_vbuf_ctrl_hdr(vbuf));

- notify = virtqueue_kick_prepare(vq);
+ atomic_inc(&vgdev->pending_commands);

spin_unlock(&vgdev->ctrlq.qlock);

- if (notify) {
- if (vgdev->disable_notify)
- vgdev->pending_notify = true;
- else
- virtqueue_notify(vq);
- }
drm_dev_exit(idx);
}

@@ -434,19 +427,20 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
}
}

-void virtio_gpu_disable_notify(struct virtio_gpu_device *vgdev)
+void virtio_gpu_notify(struct virtio_gpu_device *vgdev)
{
- vgdev->disable_notify = true;
-}
+ bool notify;

-void virtio_gpu_enable_notify(struct virtio_gpu_device *vgdev)
-{
- vgdev->disable_notify = false;
-
- if (!vgdev->pending_notify)
+ if (!atomic_read(&vgdev->pending_commands))
return;
- vgdev->pending_notify = false;
- virtqueue_notify(vgdev->ctrlq.vq);
+
+ spin_lock(&vgdev->ctrlq.qlock);
+ atomic_set(&vgdev->pending_commands, 0);
+ notify = virtqueue_kick_prepare(vgdev->ctrlq.vq);
+ spin_unlock(&vgdev->ctrlq.qlock);
+
+ if (notify)
+ virtqueue_notify(vgdev->ctrlq.vq);
}

static void virtio_gpu_queue_ctrl_buffer(struct virtio_gpu_device *vgdev,
--
2.18.2