MediaTek IOMMU don't have its power-domain. all the consumer connect
with smi-larb, then connect with smi-common.

         M4U
          |
     smi-common
          |
   -------------
   |         |    ...
   |         |
larb1     larb2
   |         |
vdec       venc

When the consumer works, it should enable the smi-larb's power which
also need enable the smi-common's power firstly.

Thus, First of all, use the device link connect the consumer and the
smi-larbs. then add device link between the smi-larb and smi-common.

This patch adds device_link between the consumer and the larbs.

Suggested-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
---
  drivers/iommu/mtk_iommu.c    | 15 +++++++++++++--
  drivers/iommu/mtk_iommu_v1.c | 14 ++++++++++++--
  2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 202e41b..735ae8d 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c

@@ -247,6 +247,7 @@ static void mtk_iommu_config(struct mtk_iommu_data *data,
  	struct mtk_smi_larb_iommu    *larb_mmu;
  	unsigned int                 larbid, portid;
  	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+	struct device_link *link;
  	int i;
  
  	for (i = 0; i < fwspec->num_ids; ++i) {

@@ -257,10 +258,20 @@ static void mtk_iommu_config(struct mtk_iommu_data *data,
  		dev_dbg(dev, "%s iommu port: %d\n",
  			enable ? "enable" : "disable", portid);
  
-		if (enable)
+		if (enable) {
  			larb_mmu->mmu |= MTK_SMI_MMU_EN(portid);
-		else
+			/* Link the consumer with the larb device(supplier) */
+			link = device_link_add(dev, larb_mmu->dev,
+					       DL_FLAG_PM_RUNTIME |
+					       DL_FLAG_AUTOREMOVE_CONSUMER);

+			if (!link) {
+				dev_err(dev, "Unable to link %s\n",
+					dev_name(larb_mmu->dev));
+				return;
+			}
+		} else {
  			larb_mmu->mmu &= ~MTK_SMI_MMU_EN(portid);
+		}
  	}
  }
  

diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
index 9386aee..022bad9 100644
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c

@@ -201,6 +201,7 @@ static void mtk_iommu_config(struct mtk_iommu_data *data,
  	struct mtk_smi_larb_iommu    *larb_mmu;
  	unsigned int                 larbid, portid;
  	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+	struct device_link *link;
  	int i;
  
  	for (i = 0; i < fwspec->num_ids; ++i) {

@@ -211,10 +212,19 @@ static void mtk_iommu_config(struct mtk_iommu_data *data,
  		dev_dbg(dev, "%s iommu port: %d\n",
  			enable ? "enable" : "disable", portid);
  
-		if (enable)
+		if (enable) {
  			larb_mmu->mmu |= MTK_SMI_MMU_EN(portid);
-		else
+			link = device_link_add(dev, larb_mmu->dev,
+					       DL_FLAG_PM_RUNTIME |
+					       DL_FLAG_AUTOREMOVE_CONSUMER);
+			if (!link) {
+				dev_err(dev, "Unable to link %s\n",
+					dev_name(larb_mmu->dev));
+				return;
+			}
+		} else {
  			larb_mmu->mmu &= ~MTK_SMI_MMU_EN(portid);
+		}
  	}
  }