linux-kernel - RE: [PATCH v5 6/7] iommu/exynos: Add runtime pm support

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Date:   Sat, 22 Oct 2016 11:20:12 +0530
From:   "Sricharan" <sricharan@...eaurora.org>
To:     "'Marek Szyprowski'" <m.szyprowski@...sung.com>,
        <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <iommu@...ts.linux-foundation.org>,
        <linux-samsung-soc@...r.kernel.org>
Cc:     "'Tomeu Vizoso'" <tomeu.vizoso@...labora.com>,
        "'Bartlomiej Zolnierkiewicz'" <b.zolnierkie@...sung.com>,
        "'Greg Kroah-Hartman'" <gregkh@...uxfoundation.org>,
        "'Kevin Hilman'" <khilman@...nel.org>,
        "'Rafael J. Wysocki'" <rjw@...ysocki.net>,
        "'Tomasz Figa'" <tomasz.figa@...il.com>,
        "'Krzysztof Kozlowski'" <krzk@...nel.org>,
        "'Inki Dae'" <inki.dae@...sung.com>,
        "'Tobias Jakobi'" <tjakobi@...h.uni-bielefeld.de>,
        "'Luis R. Rodriguez'" <mcgrof@...nel.org>,
        "'Kukjin Kim'" <kgene@...nel.org>,
        "'Mark Brown'" <broonie@...nel.org>,
        "'Lukas Wunner'" <lukas@...ner.de>
Subject: RE: [PATCH v5 6/7] iommu/exynos: Add runtime pm support

Hi Marek,

>This patch adds runtime pm implementation, which is based on previous
>suspend/resume code. SYSMMU controller is now being enabled/disabled mainly
>from the runtime pm callbacks. System sleep callbacks relies on generic
>pm_runtime_force_suspend/pm_runtime_force_resume helpers. To ensure
>internal state consistency, additional lock for runtime pm transitions
>was introduced.
>
>Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
>---
> drivers/iommu/exynos-iommu.c | 45 +++++++++++++++++++++++++++++++++++---------
> 1 file changed, 36 insertions(+), 9 deletions(-)
>
>diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
>index a959443e6f33..5e6d7bbf9b70 100644
>--- a/drivers/iommu/exynos-iommu.c
>+++ b/drivers/iommu/exynos-iommu.c
>@@ -206,6 +206,7 @@ struct sysmmu_fault_info {
> struct exynos_iommu_owner {
> 	struct list_head controllers;	/* list of sysmmu_drvdata.owner_node */
> 	struct iommu_domain *domain;	/* domain this device is attached */
>+	struct mutex rpm_lock;		/* for runtime pm of all sysmmus */
> };
>
> /*
>@@ -594,40 +595,46 @@ static int __init exynos_sysmmu_probe(struct platform_device *pdev)
> 	return 0;
> }
>
>-#ifdef CONFIG_PM_SLEEP
>-static int exynos_sysmmu_suspend(struct device *dev)
>+static int __maybe_unused exynos_sysmmu_suspend(struct device *dev)
> {
> 	struct sysmmu_drvdata *data = dev_get_drvdata(dev);
> 	struct device *master = data->master;
>
> 	if (master) {
>-		pm_runtime_put(dev);
>+		struct exynos_iommu_owner *owner = master->archdata.iommu;
>+
>+		mutex_lock(&owner->rpm_lock);
More of a device link question,
To understand, i see that with device link + runtime, the supplier
callbacks are not called for irqsafe clients, even if supplier is irqsafe.
Why so ?

> 		if (data->domain) {
> 			dev_dbg(data->sysmmu, "saving state\n");
> 			__sysmmu_disable(data);
> 		}
>+		mutex_unlock(&owner->rpm_lock);
> 	}
> 	return 0;
> }
>
>-static int exynos_sysmmu_resume(struct device *dev)
>+static int __maybe_unused exynos_sysmmu_resume(struct device *dev)
> {
> 	struct sysmmu_drvdata *data = dev_get_drvdata(dev);
> 	struct device *master = data->master;
>
> 	if (master) {
>-		pm_runtime_get_sync(dev);
>+		struct exynos_iommu_owner *owner = master->archdata.iommu;
>+
>+		mutex_lock(&owner->rpm_lock);
> 		if (data->domain) {
> 			dev_dbg(data->sysmmu, "restoring state\n");
> 			__sysmmu_enable(data);
> 		}
>+		mutex_unlock(&owner->rpm_lock);
> 	}
> 	return 0;
> }
>-#endif
>
> static const struct dev_pm_ops sysmmu_pm_ops = {
>-	SET_LATE_SYSTEM_SLEEP_PM_OPS(exynos_sysmmu_suspend, exynos_sysmmu_resume)
>+	SET_RUNTIME_PM_OPS(exynos_sysmmu_suspend, exynos_sysmmu_resume, NULL)
>+	SET_LATE_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
>+				     pm_runtime_force_resume)
> };
 Is this needed to be LATE_SYSTEM_SLEEP_PM_OPS with device links to take care
  of the order ?

Regards,
 Sricharan