<pre>
Hi, Jason:

On Wed, 2023-09-20 at 17:06 +0800, Jason-JH.Lin wrote:
> Add spinlock protection to avoid race condition on vblank event
> between mtk_drm_crtc_atomic_begin() and mtk_drm_finish_page_flip().

Reviewed-by: CK Hu <ck.hu@mediatek.com>

>
> Fixes: 119f5173628a ("drm/mediatek: Add DRM Driver for Mediatek SoC
> MT8173.")
> Signed-off-by: Jason-JH.Lin <jason-jh.lin@mediatek.com>
> Suggested-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
> Reviewed-by: Fei Shao <fshao@chromium.org>
> Tested-by: Fei Shao <fshao@chromium.org>
> ---
> drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> index b6fa4ad2f94d..cab4fe092f13 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> @@ -744,6 +744,7 @@ static void mtk_drm_crtc_atomic_begin(struct
> drm_crtc *crtc,
>
> crtc);
> struct mtk_crtc_state *mtk_crtc_state =
> to_mtk_crtc_state(crtc_state);
> struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
> +unsigned long flags;
>
> if (mtk_crtc->event && mtk_crtc_state->base.event)
> DRM_ERROR("new event while there is still a pending
> event\n");
> @@ -751,7 +752,11 @@ static void mtk_drm_crtc_atomic_begin(struct
> drm_crtc *crtc,
> if (mtk_crtc_state->base.event) {
> mtk_crtc_state->base.event->pipe =
> drm_crtc_index(crtc);
> WARN_ON(drm_crtc_vblank_get(crtc) != 0);
> +
> +spin_lock_irqsave(&crtc->dev->event_lock, flags);
> mtk_crtc->event = mtk_crtc_state->base.event;
> +spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
> +
> mtk_crtc_state->base.event = NULL;
> }
> }

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