Hi Sricharan


On 2016-10-22 07:50, Sricharan wrote:

quoted

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@samsung.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 ?

Frankly I didn't care about irqsafe runtime pm, because there is no such 
need
for Exynos platform and its drivers. Exynos power domain driver also doesn't
support irqsafe mode.

quoted

		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 ?

Hmmm. LASE_SYSTEM_SLEEP_PM_OPS is a left over from the previous versions 
of the driver,
which doesn't use device links. You are right, that "normal" 
SYSTEM_SLEEP_PM_OPS should
be enough assuming that device links will take care of the proper call 
sequence between
consumer and supplier device.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland