drm/mediatek: Add vblank register/unregister callback functions

We encountered a kernel panic issue that callback data will be NULL when
it's using in ovl irq handler. There is a timing issue between
mtk_disp_ovl_irq_handler() and mtk_ovl_disable_vblank().

To resolve this issue, we use the flow to register/unregister vblank cb:
- Register callback function and callback data when crtc creates.
- Unregister callback function and callback data when crtc destroies.

With this solution, we can assure callback data will not be NULL when
vblank is disable.

Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20220321072320.15019-1-rex-bc.chen@mediatek.com/
Fixes: 9b0704988b15 ("drm/mediatek: Register vblank callback function")
Signed-off-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
Reviewed-by: jason-jh.lin <jason-jh.lin@mediatek.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/gpu/drm/mediatek/mtk_disp_drv.h

@@ -76,9 +76,11 @@ void mtk_ovl_layer_off(struct device *dev, unsigned int idx,
 void mtk_ovl_start(struct device *dev);
 void mtk_ovl_stop(struct device *dev);
 unsigned int mtk_ovl_supported_rotations(struct device *dev);
-void mtk_ovl_enable_vblank(struct device *dev,
+void mtk_ovl_register_vblank_cb(struct device *dev,
-			   void (*vblank_cb)(void *),
+				void (*vblank_cb)(void *),
-			   void *vblank_cb_data);
+				void *vblank_cb_data);
+void mtk_ovl_unregister_vblank_cb(struct device *dev);
+void mtk_ovl_enable_vblank(struct device *dev);
 void mtk_ovl_disable_vblank(struct device *dev);
 
 void mtk_rdma_bypass_shadow(struct device *dev);
@@ -93,9 +95,11 @@ void mtk_rdma_layer_config(struct device *dev, unsigned int idx,
 			   struct cmdq_pkt *cmdq_pkt);
 void mtk_rdma_start(struct device *dev);
 void mtk_rdma_stop(struct device *dev);
-void mtk_rdma_enable_vblank(struct device *dev,
+void mtk_rdma_register_vblank_cb(struct device *dev,
-			    void (*vblank_cb)(void *),
+				 void (*vblank_cb)(void *),
-			    void *vblank_cb_data);
+				 void *vblank_cb_data);
+void mtk_rdma_unregister_vblank_cb(struct device *dev);
+void mtk_rdma_enable_vblank(struct device *dev);
 void mtk_rdma_disable_vblank(struct device *dev);
 
 #endif

drivers/gpu/drm/mediatek/mtk_disp_ovl.c

@@ -97,14 +97,28 @@ static irqreturn_t mtk_disp_ovl_irq_handler(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-void mtk_ovl_enable_vblank(struct device *dev,
+void mtk_ovl_register_vblank_cb(struct device *dev,
-			   void (*vblank_cb)(void *),
+				void (*vblank_cb)(void *),
-			   void *vblank_cb_data)
+				void *vblank_cb_data)
 {
 	struct mtk_disp_ovl *ovl = dev_get_drvdata(dev);
 
 	ovl->vblank_cb = vblank_cb;
 	ovl->vblank_cb_data = vblank_cb_data;
+}
+
+void mtk_ovl_unregister_vblank_cb(struct device *dev)
+{
+	struct mtk_disp_ovl *ovl = dev_get_drvdata(dev);
+
+	ovl->vblank_cb = NULL;
+	ovl->vblank_cb_data = NULL;
+}
+
+void mtk_ovl_enable_vblank(struct device *dev)
+{
+	struct mtk_disp_ovl *ovl = dev_get_drvdata(dev);
+
 	writel(0x0, ovl->regs + DISP_REG_OVL_INTSTA);
 	writel_relaxed(OVL_FME_CPL_INT, ovl->regs + DISP_REG_OVL_INTEN);
 }
@@ -113,8 +127,6 @@ void mtk_ovl_disable_vblank(struct device *dev)
 {
 	struct mtk_disp_ovl *ovl = dev_get_drvdata(dev);
 
-	ovl->vblank_cb = NULL;
-	ovl->vblank_cb_data = NULL;
 	writel_relaxed(0x0, ovl->regs + DISP_REG_OVL_INTEN);
 }
 

drivers/gpu/drm/mediatek/mtk_disp_rdma.c

@@ -95,24 +95,32 @@ static void rdma_update_bits(struct device *dev, unsigned int reg,
 	writel(tmp, rdma->regs + reg);
 }
 
-void mtk_rdma_enable_vblank(struct device *dev,
+void mtk_rdma_register_vblank_cb(struct device *dev,
-			    void (*vblank_cb)(void *),
+				 void (*vblank_cb)(void *),
-			    void *vblank_cb_data)
+				 void *vblank_cb_data)
 {
 	struct mtk_disp_rdma *rdma = dev_get_drvdata(dev);
 
 	rdma->vblank_cb = vblank_cb;
 	rdma->vblank_cb_data = vblank_cb_data;
+}
+
+void mtk_rdma_unregister_vblank_cb(struct device *dev)
+{
+	struct mtk_disp_rdma *rdma = dev_get_drvdata(dev);
+
+	rdma->vblank_cb = NULL;
+	rdma->vblank_cb_data = NULL;
+}
+
+void mtk_rdma_enable_vblank(struct device *dev)
+{
 	rdma_update_bits(dev, DISP_REG_RDMA_INT_ENABLE, RDMA_FRAME_END_INT,
 			 RDMA_FRAME_END_INT);
 }
 
 void mtk_rdma_disable_vblank(struct device *dev)
 {
-	struct mtk_disp_rdma *rdma = dev_get_drvdata(dev);
-
-	rdma->vblank_cb = NULL;
-	rdma->vblank_cb_data = NULL;
 	rdma_update_bits(dev, DISP_REG_RDMA_INT_ENABLE, RDMA_FRAME_END_INT, 0);
 }
 

drivers/gpu/drm/mediatek/mtk_drm_crtc.c

@@ -152,6 +152,7 @@ static void mtk_drm_cmdq_pkt_destroy(struct cmdq_pkt *pkt)
 static void mtk_drm_crtc_destroy(struct drm_crtc *crtc)
 {
 	struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
+	int i;
 
 	mtk_mutex_put(mtk_crtc->mutex);
 #if IS_REACHABLE(CONFIG_MTK_CMDQ)
@@ -162,6 +163,14 @@ static void mtk_drm_crtc_destroy(struct drm_crtc *crtc)
 		mtk_crtc->cmdq_client.chan = NULL;
 	}
 #endif
+
+	for (i = 0; i < mtk_crtc->ddp_comp_nr; i++) {
+		struct mtk_ddp_comp *comp;
+
+		comp = mtk_crtc->ddp_comp[i];
+		mtk_ddp_comp_unregister_vblank_cb(comp);
+	}
+
 	drm_crtc_cleanup(crtc);
 }
 
@@ -618,7 +627,7 @@ static int mtk_drm_crtc_enable_vblank(struct drm_crtc *crtc)
 	struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
 	struct mtk_ddp_comp *comp = mtk_crtc->ddp_comp[0];
 
-	mtk_ddp_comp_enable_vblank(comp, mtk_crtc_ddp_irq, &mtk_crtc->base);
+	mtk_ddp_comp_enable_vblank(comp);
 
 	return 0;
 }
@@ -927,6 +936,9 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
 			if (comp->funcs->ctm_set)
 				has_ctm = true;
 		}
+
+		mtk_ddp_comp_register_vblank_cb(comp, mtk_crtc_ddp_irq,
+						&mtk_crtc->base);
 	}
 
 	for (i = 0; i < mtk_crtc->ddp_comp_nr; i++)

drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c

@@ -297,6 +297,8 @@ static const struct mtk_ddp_comp_funcs ddp_ovl = {
 	.config = mtk_ovl_config,
 	.start = mtk_ovl_start,
 	.stop = mtk_ovl_stop,
+	.register_vblank_cb = mtk_ovl_register_vblank_cb,
+	.unregister_vblank_cb = mtk_ovl_unregister_vblank_cb,
 	.enable_vblank = mtk_ovl_enable_vblank,
 	.disable_vblank = mtk_ovl_disable_vblank,
 	.supported_rotations = mtk_ovl_supported_rotations,
@@ -321,6 +323,8 @@ static const struct mtk_ddp_comp_funcs ddp_rdma = {
 	.config = mtk_rdma_config,
 	.start = mtk_rdma_start,
 	.stop = mtk_rdma_stop,
+	.register_vblank_cb = mtk_rdma_register_vblank_cb,
+	.unregister_vblank_cb = mtk_rdma_unregister_vblank_cb,
 	.enable_vblank = mtk_rdma_enable_vblank,
 	.disable_vblank = mtk_rdma_disable_vblank,
 	.layer_nr = mtk_rdma_layer_nr,

drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h

@@ -48,9 +48,11 @@ struct mtk_ddp_comp_funcs {
 		       unsigned int bpc, struct cmdq_pkt *cmdq_pkt);
 	void (*start)(struct device *dev);
 	void (*stop)(struct device *dev);
-	void (*enable_vblank)(struct device *dev,
+	void (*register_vblank_cb)(struct device *dev,
-			      void (*vblank_cb)(void *),
+				   void (*vblank_cb)(void *),
-			      void *vblank_cb_data);
+				   void *vblank_cb_data);
+	void (*unregister_vblank_cb)(struct device *dev);
+	void (*enable_vblank)(struct device *dev);
 	void (*disable_vblank)(struct device *dev);
 	unsigned int (*supported_rotations)(struct device *dev);
 	unsigned int (*layer_nr)(struct device *dev);
@@ -110,12 +112,25 @@ static inline void mtk_ddp_comp_stop(struct mtk_ddp_comp *comp)
 		comp->funcs->stop(comp->dev);
 }
 
-static inline void mtk_ddp_comp_enable_vblank(struct mtk_ddp_comp *comp,
+static inline void mtk_ddp_comp_register_vblank_cb(struct mtk_ddp_comp *comp,
-					      void (*vblank_cb)(void *),
+						   void (*vblank_cb)(void *),
-					      void *vblank_cb_data)
+						   void *vblank_cb_data)
+{
+	if (comp->funcs && comp->funcs->register_vblank_cb)
+		comp->funcs->register_vblank_cb(comp->dev, vblank_cb,
+						vblank_cb_data);
+}
+
+static inline void mtk_ddp_comp_unregister_vblank_cb(struct mtk_ddp_comp *comp)
+{
+	if (comp->funcs && comp->funcs->unregister_vblank_cb)
+		comp->funcs->unregister_vblank_cb(comp->dev);
+}
+
+static inline void mtk_ddp_comp_enable_vblank(struct mtk_ddp_comp *comp)
 {
 	if (comp->funcs && comp->funcs->enable_vblank)
-		comp->funcs->enable_vblank(comp->dev, vblank_cb, vblank_cb_data);
+		comp->funcs->enable_vblank(comp->dev);
 }
 
 static inline void mtk_ddp_comp_disable_vblank(struct mtk_ddp_comp *comp)