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

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Date:   Mon, 24 Oct 2016 17:45:13 +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,

>Hi Sricharan
>
>
>On 2016-10-22 07:50, Sricharan wrote:
>>
>>> 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 ?
>
>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.
  ok, i asked this because, i was doing the same thing for arm-smmu driver
   and thought that when we depend on device-link for doing the runtime pm,
   then it might not work for irqsafe master. Probably i can ask this on device link
    series post.

Regards,
 Sricharan