Re: [PATCH 04/13] iommu/mediatek: Add device_link between the consumer and the larb devices

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On 01/01/2019 04:51, Yong Wu wrote:
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@xxxxxxxxxxxx>
Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
---
  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);

This looks technically wrong, since we get here from mtk_iommu_attach_device(), and in theory a device could get attached to any number of domains over its lifetime, so adding a link at this point when there's no corresponding cleanup on detach is definitely unbalanced. If you want this layer to manage the link on behalf of the consumer, it would probably be better to do it at the point of mtk_iommu_add_device(), and either track it for manual cleanup in mtk_iommu_remove_device() or rely on AUTOREMOVE_SUPPLIER.

Robin.

+			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);
+		}
  	}
  }



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