media: platform: mtk-mdp3: Use refcount_t for job_count

Use an API that resembles more the actual use of job_count.

Found by cocci:
drivers/media/platform/mediatek/mdp3/mtk-mdp3-cmdq.c:527:5-24: WARNING: atomic_dec_and_test variation before object free at line 541.
drivers/media/platform/mediatek/mdp3/mtk-mdp3-cmdq.c:578:6-25: WARNING: atomic_dec_and_test variation before object free at line 581.

Link: https://lore.kernel.org/linux-media/20240429-fix-cocci-v3-12-3c4865f5a4b0@chromium.org
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Author: ribalda

drivers/media/platform/mediatek/mdp3/mtk-mdp3-cmdq.c

@@ -524,7 +524,7 @@ static void mdp_auto_release_work(struct work_struct *work)
 	mdp_comp_clocks_off(&mdp->pdev->dev, cmd->comps,
 			    cmd->num_comps);
 
-	if (atomic_dec_and_test(&mdp->job_count)) {
+	if (refcount_dec_and_test(&mdp->job_count)) {
 		if (cmd->mdp_ctx)
 			mdp_m2m_job_finish(cmd->mdp_ctx);
 
@@ -575,7 +575,7 @@ static void mdp_handle_cmdq_callback(struct mbox_client *cl, void *mssg)
 		mdp_comp_clocks_off(&mdp->pdev->dev, cmd->comps,
 				    cmd->num_comps);
 
-		if (atomic_dec_and_test(&mdp->job_count))
+		if (refcount_dec_and_test(&mdp->job_count))
 			wake_up(&mdp->callback_wq);
 
 		mdp_cmdq_pkt_destroy(&cmd->pkt);
@@ -724,9 +724,9 @@ int mdp_cmdq_send(struct mdp_dev *mdp, struct mdp_cmdq_param *param)
 	int i, ret;
 	u8 pp_used = __get_pp_num(param->param->type);
 
-	atomic_set(&mdp->job_count, pp_used);
+	refcount_set(&mdp->job_count, pp_used);
 	if (atomic_read(&mdp->suspended)) {
-		atomic_set(&mdp->job_count, 0);
+		refcount_set(&mdp->job_count, 0);
 		return -ECANCELED;
 	}
 
@@ -764,7 +764,7 @@ int mdp_cmdq_send(struct mdp_dev *mdp, struct mdp_cmdq_param *param)
 		mdp_comp_clocks_off(&mdp->pdev->dev, cmd[i]->comps,
 				    cmd[i]->num_comps);
 err_cancel_job:
-	atomic_set(&mdp->job_count, 0);
+	refcount_set(&mdp->job_count, 0);
 
 	return ret;
 }

drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c

@@ -380,14 +380,14 @@ static int __maybe_unused mdp_suspend(struct device *dev)
 
 	atomic_set(&mdp->suspended, 1);
 
-	if (atomic_read(&mdp->job_count)) {
+	if (refcount_read(&mdp->job_count)) {
 		ret = wait_event_timeout(mdp->callback_wq,
-					 !atomic_read(&mdp->job_count),
+					 !refcount_read(&mdp->job_count),
 					 2 * HZ);
 		if (ret == 0) {
 			dev_err(dev,
 				"%s:flushed cmdq task incomplete, count=%d\n",
-				__func__, atomic_read(&mdp->job_count));
+				__func__, refcount_read(&mdp->job_count));
 			return -EBUSY;
 		}
 	}

drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.h

@@ -134,7 +134,7 @@ struct mdp_dev {
 	/* synchronization protect for m2m device operation */
 	struct mutex				m2m_lock;
 	atomic_t				suspended;
-	atomic_t				job_count;
+	refcount_t				job_count;
 };
 
 struct mdp_pipe_info {

drivers/media/platform/mediatek/mdp3/mtk-mdp3-m2m.c

@@ -104,14 +104,14 @@ static void mdp_m2m_device_run(void *priv)
 	task.cb_data = NULL;
 	task.mdp_ctx = ctx;
 
-	if (atomic_read(&ctx->mdp_dev->job_count)) {
+	if (refcount_read(&ctx->mdp_dev->job_count)) {
 		ret = wait_event_timeout(ctx->mdp_dev->callback_wq,
-					 !atomic_read(&ctx->mdp_dev->job_count),
+					 !refcount_read(&ctx->mdp_dev->job_count),
 					 2 * HZ);
 		if (ret == 0) {
 			dev_err(&ctx->mdp_dev->pdev->dev,
 				"%d jobs not yet done\n",
-				atomic_read(&ctx->mdp_dev->job_count));
+				refcount_read(&ctx->mdp_dev->job_count));
 			goto worker_end;
 		}
 	}