Patch "drm/mediatek: Add spinlock for setting vblank event in atomic_begin" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/mediatek: Add spinlock for setting vblank event in atomic_begin

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-mediatek-add-spinlock-for-setting-vblank-event-i.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 3288a1c327bc630827b992e44d89496d36780d77
Author: Jason-JH.Lin <jason-jh.lin@xxxxxxxxxxxx>
Date:   Wed Sep 20 17:06:58 2023 +0800

    drm/mediatek: Add spinlock for setting vblank event in atomic_begin
    
    [ Upstream commit fe4c5f662097978b6c91c23a13c24ed92339a180 ]
    
    Add spinlock protection to avoid race condition on vblank event
    between mtk_drm_crtc_atomic_begin() and mtk_drm_finish_page_flip().
    
    Fixes: 119f5173628a ("drm/mediatek: Add DRM Driver for Mediatek SoC MT8173.")
    Signed-off-by: Jason-JH.Lin <jason-jh.lin@xxxxxxxxxxxx>
    Suggested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
    Reviewed-by: Alexandre Mergnat <amergnat@xxxxxxxxxxxx>
    Reviewed-by: Fei Shao <fshao@xxxxxxxxxxxx>
    Tested-by: Fei Shao <fshao@xxxxxxxxxxxx>
    Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
    Reviewed-by: CK Hu <ck.hu@xxxxxxxxxxxx>
    Link: https://patchwork.kernel.org/project/dri-devel/patch/20230920090658.31181-1-jason-jh.lin@xxxxxxxxxxxx/
    Signed-off-by: Chun-Kuang Hu <chunkuang.hu@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
index f2264633be1b7..d6781e54b3356 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
@@ -680,6 +680,7 @@ 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");
@@ -687,7 +688,11 @@ 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;
 	}
 }