iommu/mediatek: Add platform_device_put for recovering the device refcnt

Add platform_device_put to match with of_find_device_by_node.

Meanwhile, I add a new variable "pcommdev" which is for smi common device.
Otherwise, "platform_device_put(plarbdev)" for smi-common dev may be not
readable. And add a checking for whether pcommdev is NULL.

Fixes: d2e9a11 ("iommu/mediatek: Contain MM IOMMU flow with the MM TYPE")
Signed-off-by: Yong Wu <[email protected]>
Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
Reviewed-by: Matthias Brugger <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Joerg Roedel <[email protected]>

Author: YongWu-HF

drivers/iommu/mtk_iommu.c

@@ -1055,7 +1055,7 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
 				  struct mtk_iommu_data *data)
 {
 	struct device_node *larbnode, *smicomm_node, *smi_subcomm_node;
-	struct platform_device *plarbdev;
+	struct platform_device *plarbdev, *pcommdev;
 	struct device_link *link;
 	int i, larb_nr, ret;
 
@@ -1086,12 +1086,14 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
 		}
 		if (!plarbdev->dev.driver) {
 			of_node_put(larbnode);
+			platform_device_put(plarbdev);
 			return -EPROBE_DEFER;
 		}
 		data->larb_imu[id].dev = &plarbdev->dev;
 
 		component_match_add_release(dev, match, component_release_of,
 					    component_compare_of, larbnode);
+		platform_device_put(plarbdev);
 	}
 
 	/* Get smi-(sub)-common dev from the last larb. */
@@ -1109,12 +1111,15 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
 	else
 		smicomm_node = smi_subcomm_node;
 
-	plarbdev = of_find_device_by_node(smicomm_node);
+	pcommdev = of_find_device_by_node(smicomm_node);
 	of_node_put(smicomm_node);
-	data->smicomm_dev = &plarbdev->dev;
+	if (!pcommdev)
+		return -ENODEV;
+	data->smicomm_dev = &pcommdev->dev;
 
 	link = device_link_add(data->smicomm_dev, dev,
 			       DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME);
+	platform_device_put(pcommdev);
 	if (!link) {
 		dev_err(dev, "Unable to link %s.\n", dev_name(data->smicomm_dev));
 		return -EINVAL;