[PATCH v3 2/2] drm/mediatek: change config_lock from spin_lock to spin_lock_irqsave

[Jason-JH.Lin via B4 Relay]

From: "Jason-JH.Lin" <jason-jh....@mediatek.com>

Operations within spin_locks are limited to fast memory access and
confirmation of minimum lock duration.

Although using spin_lock with config_lock seems to ensure shorter hold
times, it is safer to use spin_lock_irqsave due to potential deadlocks
and nested interrupt scenarios in interrupt contexts.

So change config_lock from spin_lock to spin_lock_irqsave.

Fixes: 7f82d9c43879 ("drm/mediatek: Clear pending flag when cmdq packet is 
done")
Signed-off-by: Jason-JH.Lin <jason-jh....@mediatek.com>
---
 drivers/gpu/drm/mediatek/mtk_crtc.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_crtc.c 
b/drivers/gpu/drm/mediatek/mtk_crtc.c
index b752c0b46383..d7f0926f896d 100644
--- a/drivers/gpu/drm/mediatek/mtk_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_crtc.c
@@ -108,14 +108,16 @@ static void mtk_crtc_finish_page_flip(struct mtk_crtc 
*mtk_crtc)
 
 static void mtk_drm_finish_page_flip(struct mtk_crtc *mtk_crtc)
 {
+       unsigned long flags;
+
        drm_crtc_handle_vblank(&mtk_crtc->base);
 
-       spin_lock(&mtk_crtc->config_lock);
+       spin_lock_irqsave(&mtk_crtc->config_lock, flags);
        if (!mtk_crtc->config_updating && mtk_crtc->pending_needs_vblank) {
                mtk_crtc_finish_page_flip(mtk_crtc);
                mtk_crtc->pending_needs_vblank = false;
        }
-       spin_unlock(&mtk_crtc->config_lock);
+       spin_unlock_irqrestore(&mtk_crtc->config_lock, flags);
 }
 
 #if IS_REACHABLE(CONFIG_MTK_CMDQ)
@@ -313,16 +315,16 @@ static void ddp_cmdq_cb(struct mbox_client *cl, void 
*mssg)
        struct mtk_crtc *mtk_crtc = container_of(cmdq_cl, struct mtk_crtc, 
cmdq_client);
        struct mtk_crtc_state *state;
        unsigned int i;
+       unsigned long flags;
 
        if (data->sta < 0)
                return;
 
        state = to_mtk_crtc_state(mtk_crtc->base.state);
 
-       spin_lock(&mtk_crtc->config_lock);
-
+       spin_lock_irqsave(&mtk_crtc->config_lock, flags);
        if (mtk_crtc->config_updating) {
-               spin_unlock(&mtk_crtc->config_lock);
+               spin_unlock_irqrestore(&mtk_crtc->config_lock, flags);
                goto ddp_cmdq_cb_out;
        }
 
@@ -352,7 +354,7 @@ static void ddp_cmdq_cb(struct mbox_client *cl, void *mssg)
                mtk_crtc->pending_async_planes = false;
        }
 
-       spin_unlock(&mtk_crtc->config_lock);
+       spin_unlock_irqrestore(&mtk_crtc->config_lock, flags);
 
 ddp_cmdq_cb_out:
 
@@ -585,12 +587,13 @@ static void mtk_crtc_update_config(struct mtk_crtc 
*mtk_crtc, bool needs_vblank)
        struct mtk_drm_private *priv = crtc->dev->dev_private;
        unsigned int pending_planes = 0, pending_async_planes = 0;
        int i;
+       unsigned long flags;
 
        mutex_lock(&mtk_crtc->hw_lock);
 
-       spin_lock(&mtk_crtc->config_lock);
+       spin_lock_irqsave(&mtk_crtc->config_lock, flags);
        mtk_crtc->config_updating = true;
-       spin_unlock(&mtk_crtc->config_lock);
+       spin_unlock_irqrestore(&mtk_crtc->config_lock, flags);
 
        if (needs_vblank)
                mtk_crtc->pending_needs_vblank = true;
@@ -645,9 +648,9 @@ static void mtk_crtc_update_config(struct mtk_crtc 
*mtk_crtc, bool needs_vblank)
                mbox_client_txdone(mtk_crtc->cmdq_client.chan, 0);
        }
 #endif
-       spin_lock(&mtk_crtc->config_lock);
+       spin_lock_irqsave(&mtk_crtc->config_lock, flags);
        mtk_crtc->config_updating = false;
-       spin_unlock(&mtk_crtc->config_lock);
+       spin_unlock_irqrestore(&mtk_crtc->config_lock, flags);
 
        mutex_unlock(&mtk_crtc->hw_lock);
 }

-- 
2.43.0