Messages in this thread | | | Subject | Re: [PATCH v5 7/7] iommu/exynos: Use device dependency links to control runtime pm | From | Marek Szyprowski <> | Date | Mon, 24 Oct 2016 14:39:15 +0200 |
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Hi Sricharan,
On 2016-10-24 14:29, Sricharan wrote: >>>> 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@samsung.com> >>>> --- >>>> 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 ? >> I don't know what is "multiple sids" case, but if given SYSMMU master >> device (supplier) >> has multiple SYSMMU controllers (consumers), then links will be created >> for each SYSMMU >> controller. Please note that this code is based on vanilla v4.9-rc1, >> which calls >> of_xlate() callback only once for every iommu for given master device. >> Your IOMMU >> deferred probe patches change this, but I already posted a fix for >> Exynos IOMMU driver >> to handle such case. > By multiple sids, i meant iommus = <&phandle sid1 sid2 .. sidn> case, > so xlate would be called multiples for the same master without deferred > probing also. But the fix that you showed on the other thread would work > here as well or maybe if you dont have masters with multiple sids you wont > have any issues as well.
Exynos SYSMMU driver always use "#iommu-cells = <0>", so it doesn't support multiple sids. However there is a case with 2 SYSMMU controllers attached to the same master device: "iommus = <&sysmmu_mfc_l>, <&sysmmu_mfc_r>;".
Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
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