No functional change. Just improve safety from dts.

All the larbs that connect to one IOMMU must connect with the same
smi-common. This patch checks all the mediatek,smi property for each
larb, If their mediatek,smi are different, it will return fails.
Also avoid there is no available smi-larb nodes.

Suggested-by: Guenter Roeck <gro...@chromium.org>
Signed-off-by: Yong Wu <yong...@mediatek.com>
---
 drivers/iommu/mtk_iommu.c | 49 ++++++++++++++++++++++++++-------------
 1 file changed, 33 insertions(+), 16 deletions(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index a869d4aee7b3..5e86fd48928a 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -1044,7 +1044,7 @@ static const struct component_master_ops 
mtk_iommu_com_ops = {
 static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match 
**match,
                                  struct mtk_iommu_data *data)
 {
-       struct device_node *larbnode, *smicomm_node, *smi_subcomm_node;
+       struct device_node *larbnode, *frst_avail_smicomm_node = NULL;
        struct platform_device *plarbdev;
        struct device_link *link;
        int i, larb_nr, ret;
@@ -1056,6 +1056,7 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, 
struct component_match **m
                return -EINVAL;
 
        for (i = 0; i < larb_nr; i++) {
+               struct device_node *smicomm_node, *smi_subcomm_node;
                u32 id;
 
                larbnode = of_parse_phandle(dev->of_node, "mediatek,larbs", i);
@@ -1091,27 +1092,43 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, 
struct component_match **m
                }
                data->larb_imu[id].dev = &plarbdev->dev;
 
+               /* Get smi-(sub)-common dev from the last larb. */
+               smi_subcomm_node = of_parse_phandle(larbnode, "mediatek,smi", 
0);
+               if (!smi_subcomm_node) {
+                       ret = -EINVAL;
+                       goto err_larbnode_put;
+               }
+
+               /*
+                * It may have two level smi-common. the node is smi-sub-common 
if it
+                * has a new mediatek,smi property. otherwise it is smi-commmon.
+                */
+               smicomm_node = of_parse_phandle(smi_subcomm_node, 
"mediatek,smi", 0);
+               if (smicomm_node)
+                       of_node_put(smi_subcomm_node);
+               else
+                       smicomm_node = smi_subcomm_node;
+
+               if (!frst_avail_smicomm_node) {
+                       frst_avail_smicomm_node = smicomm_node;
+               } else if (frst_avail_smicomm_node != smicomm_node) {
+                       dev_err(dev, "mediatek,smi is not right @larb%d.", id);
+                       of_node_put(smicomm_node);
+                       ret = -EINVAL;
+                       goto err_larbnode_put;
+               } else {
+                       of_node_put(smicomm_node);
+               }
+
                component_match_add_release(dev, match, component_release_of,
                                            component_compare_of, larbnode);
        }
 
-       /* Get smi-(sub)-common dev from the last larb. */
-       smi_subcomm_node = of_parse_phandle(larbnode, "mediatek,smi", 0);
-       if (!smi_subcomm_node)
+       if (!frst_avail_smicomm_node)
                return -EINVAL;
 
-       /*
-        * It may have two level smi-common. the node is smi-sub-common if it
-        * has a new mediatek,smi property. otherwise it is smi-commmon.
-        */
-       smicomm_node = of_parse_phandle(smi_subcomm_node, "mediatek,smi", 0);
-       if (smicomm_node)
-               of_node_put(smi_subcomm_node);
-       else
-               smicomm_node = smi_subcomm_node;
-
-       plarbdev = of_find_device_by_node(smicomm_node);
-       of_node_put(smicomm_node);
+       plarbdev = of_find_device_by_node(frst_avail_smicomm_node);
+       of_node_put(frst_avail_smicomm_node);
        data->smicomm_dev = &plarbdev->dev;
 
        link = device_link_add(data->smicomm_dev, dev,
-- 
2.18.0

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