RE: [PATCH v5 7/7] iommu/exynos: Use device dependency links to control runtime pm

[Sricharan]

Hi Marek,
>This patch uses recently introduced device dependency links to track the
>runtime pm state of the master's device. This way each SYSMMU controller
>is set to runtime active only when its master's device is active and can
>restore or save its state instead of being activated all the time when
>attached to the given master device. This way SYSMMU controllers no longer
>prevents respective power domains to be turned off when master's device
>is not being used.
>
>Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
>---
> drivers/iommu/exynos-iommu.c | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
>diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
>index 5e6d7bbf9b70..59b4f2ce4f5f 100644
>--- a/drivers/iommu/exynos-iommu.c
>+++ b/drivers/iommu/exynos-iommu.c
>@@ -781,10 +781,6 @@ static void exynos_iommu_detach_device(struct iommu_domain *iommu_domain,
> 	if (!has_sysmmu(dev) || owner->domain != iommu_domain)
> 		return;
>
>-	list_for_each_entry(data, &owner->controllers, owner_node) {
>-		pm_runtime_put_sync(data->sysmmu);
>-	}
>-
> 	mutex_lock(&owner->rpm_lock);
>
> 	list_for_each_entry(data, &owner->controllers, owner_node) {
>@@ -848,10 +844,6 @@ static int exynos_iommu_attach_device(struct iommu_domain *iommu_domain,
>
> 	mutex_unlock(&owner->rpm_lock);
>
>-	list_for_each_entry(data, &owner->controllers, owner_node) {
>-		pm_runtime_get_sync(data->sysmmu);
>-	}
>-
> 	dev_dbg(dev, "%s: Attached IOMMU with pgtable %pa\n", __func__,
> 		&pagetable);
>
>@@ -1232,6 +1224,14 @@ static int exynos_iommu_of_xlate(struct device *dev,
>
> 	list_add_tail(&data->owner_node, &owner->controllers);
> 	data->master = dev;
>+
>+	/*
>+	 * SYSMMU will be runtime activated via device link (dependency) to its
>+	 * master device, so there are no direct calls to pm_runtime_get/put
>+	 * in this driver.
>+	 */
>+	device_link_add(dev, data->sysmmu, DL_FLAG_PM_RUNTIME);
>+
  So in the case of master with multiple sids, this would be called multiple times
  for the same master ?

Regards,
 Sricharan