nouveau page_flip function implement not wait vblank, which cause screen garbage

[chris <wwzbwwzb@xxxxxxx>]

Dear,

I use NVidia Geforce 7300GT graphics card in my PC, and Linux 3.1rc4 kernel code, git drm 2.4.36. 
  When I run the vbltest program, it prints  "60HZ"  which indicated the implementation of drmWaitVBlank() and drm_vblank_wait()  is correct.
  But when I run modetest with option " -v -s 12:1280x1024" , it prints high fresh rate up to "150 HZ" .  I examing the code , and found that no waiting vblank operation is processed in nouveau_crtc_page_flip() function. The screen  produced lots of garbage and blink very much.
 int
nouveau_crtc_page_flip(struct drm_crtc *crtc, struct drm_framebuffer *fb,
               struct drm_pending_vblank_event *event)
{
......
}
I study the i915 intel_crtc_page_flip implementation.
static int intel_crtc_page_flip(stru ct drm_crtc *crtc,
                struct drm_framebuffer *fb,
                struct drm_pending_vblank_event *event)
{
......

    ret = drm_vblank_get(dev, intel_crtc->pipe);
    if (ret)
        goto cleanup_objs;

    work->pending_flip_obj = obj;

    work->enable_stall_check = true;

    /* Block clients from rendering to the new back buffer until
     * the flip occurs and the object is no longer visible.
     */
    atomic_add(1 << intel_crtc->plane, &work->old_fb_obj->pending_flip);

    ret = dev_priv->display.queue_flip(dev, crtc, fb, obj);
 &nb sp;  if (ret)
        goto cleanup_pending;
......
}

after vblank irq acquired, the interrupt isr will wakup the runqueue.
6159 static void do_intel_finish_page_flip(struct drm_device *dev,
6160                       struct drm_crtc *crtc)
6161 {
......
6211         list_add_tail(&e->base.link,
6212                   &e->base.file_priv->event_list);
6213         wake_up_interruptible(&e->base.file_priv->event_wait);
6214     }
6215
6216     drm_vblank_put(dev, intel_crtc->pipe);
6217


Is there anyone use the same  driver and foun d this issues can tell me "is it a bug"?

Thanks!

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