[PATCH v1, 1/1] drm/mediatek: fixup crtc event null pointer issue

[CK Hu]

Hi, Yongqiang:

On Mon, 2022-03-14 at 15:42 +0800, Yongqiang Niu wrote:
> if crtc event is null pointer, do not send vblank event

This is a bug-fix, so add a Fixes tag here.

> 
> Signed-off-by: Yongqiang Niu <yongqiang.niu at mediatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> index d661edf7e0fe..265fed446628 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> @@ -92,6 +92,9 @@ static void mtk_drm_crtc_finish_page_flip(struct
> mtk_drm_crtc *mtk_crtc)
>  	struct drm_crtc *crtc = &mtk_crtc->base;
>  	unsigned long flags;
>  
> +	if (!mtk_crtc->event)
> +		return;
> +
>  	spin_lock_irqsave(&crtc->dev->event_lock, flags);
>  	drm_crtc_send_vblank_event(crtc, mtk_crtc->event);

I think pending_needs_vblank is used to protect this situation. It
seems that pending_needs_vblank should be protected by critical
section.

Regards,
CK

>  	drm_crtc_vblank_put(crtc);