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SubjectRe: [PATCH 1/4] IOMMU: Make dwo drivers use stateless device links
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Hi Rafael,

On 2019-01-29 00:05, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> The device links used by rockchip-iommu and exynos-iommu are
> completely managed by these drivers within the IOMMU framework,
> so there is no reason to involve the driver core in the management
> of these links.
>
> For this reason, make rockchip-iommu and exynos-iommu pass
> DL_FLAG_STATELESS in flags to device_link_add(), so that the device
> links used by them are stateless.
>
> [Note that this change is requisite for a subsequent one that will
> rework the management of stateful device links in the driver core
> and it will not be compatible with the two drivers in question any
> more.]
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Indeed there is no need to use driver-state tracking feature of device
links in this case.

For the Exynos IOMMU driver:

Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>

> ---
> drivers/iommu/exynos-iommu.c | 1 +
> drivers/iommu/rockchip-iommu.c | 3 ++-
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> Index: linux-pm/drivers/iommu/rockchip-iommu.c
> ===================================================================
> --- linux-pm.orig/drivers/iommu/rockchip-iommu.c
> +++ linux-pm/drivers/iommu/rockchip-iommu.c
> @@ -1071,7 +1071,8 @@ static int rk_iommu_add_device(struct de
> iommu_group_put(group);
>
> iommu_device_link(&iommu->iommu, dev);
> - data->link = device_link_add(dev, iommu->dev, DL_FLAG_PM_RUNTIME);
> + data->link = device_link_add(dev, iommu->dev,
> + DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME);
>
> return 0;
> }
> Index: linux-pm/drivers/iommu/exynos-iommu.c
> ===================================================================
> --- linux-pm.orig/drivers/iommu/exynos-iommu.c
> +++ linux-pm/drivers/iommu/exynos-iommu.c
> @@ -1260,6 +1260,7 @@ static int exynos_iommu_add_device(struc
> * direct calls to pm_runtime_get/put in this driver.
> */
> data->link = device_link_add(dev, data->sysmmu,
> + DL_FLAG_STATELESS |
> DL_FLAG_PM_RUNTIME);
> }
> iommu_group_put(group);
>
>
>
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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