[PATCH 2/7] drm/mediatek: put "event" in critical section

[Bibby Hsieh <bibby.hsieh@mediatek.com>]

The state->base.event variable would be access by thread context
in mtk_drm_crtc_atomic_begin() or by interrupt context in
mtk_drm_crtc_finish_page_flip(), so each part should be a critical
section. Fix it.

Fixes: 119f5173628a ("drm/mediatek: Add DRM Driver for Mediatek SoC MT8173.")

Signed-off-by: Bibby Hsieh <bibby.hsieh@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 68b92adc96bb..e38506d7a4e8 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
@@ -486,12 +486,15 @@ static void mtk_drm_crtc_atomic_begin(struct drm_crtc *crtc,
 	if (mtk_crtc->event && state->base.event)
 		DRM_ERROR("new event while there is still a pending event\n");
 
+	spin_lock_irq(&crtc->dev->event_lock);
 	if (state->base.event) {
 		state->base.event->pipe = drm_crtc_index(crtc);
 		WARN_ON(drm_crtc_vblank_get(crtc) != 0);
+		WARN_ON(mtk_crtc->event);
 		mtk_crtc->event = state->base.event;
 		state->base.event = NULL;
 	}
+	spin_unlock_irq(&crtc->dev->event_lock);
 }
 
 static void mtk_drm_crtc_atomic_flush(struct drm_crtc *crtc,
-- 
2.18.0
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