Message-id: <20130809164943.fe4b673e92b3f7680562f29b@samsung.com>
Date:	Fri, 09 Aug 2013 16:49:43 +0900
From:	Cho KyongHo <pullip.cho@...sung.com>
To:	Tomasz Figa <tomasz.figa@...il.com>
Cc:	'Linux ARM Kernel' <linux-arm-kernel@...ts.infradead.org>,
	'Linux IOMMU' <iommu@...ts.linux-foundation.org>,
	'Linux Kernel' <linux-kernel@...r.kernel.org>,
	'Linux Samsung SOC' <linux-samsung-soc@...r.kernel.org>,
	devicetree@...r.kernel.org, 'Joerg Roedel' <joro@...tes.org>,
	'Kukjin Kim' <kgene.kim@...sung.com>,
	'Prathyush' <prathyush.k@...sung.com>,
	'Rahul Sharma' <rahul.sharma@...sung.com>,
	'Subash Patel' <supash.ramaswamy@...aro.org>,
	'Grant Grundler' <grundler@...omium.org>,
	'Antonios Motakis' <a.motakis@...tualopensystems.com>,
	kvmarm@...ts.cs.columbia.edu,
	'Sachin Kamat' <sachin.kamat@...aro.org>
Subject: Re: [PATCH v9 14/16] iommu/exynos: add support for power management
 subsystems.

On Fri, 09 Aug 2013 01:03:05 +0200, Tomasz Figa wrote:
> Hi KyongHo,
> 
> nit: Please drop the trailing dot at the end of patch subject.
> 

Oh. I didn't catch that.
Thank you.

> On Thursday 08 of August 2013 18:41:17 Cho KyongHo wrote:
> > This adds support for Advance Power Management and Runtime Power
> > Management.
> 
> This patch adds support for system-wide and runtime power management.
> 

Ok.

> > Since System MMU is located in the same local power domain of its
> > master H/W, System MMU must be initialized before it is working if
> > its power domain was ever turned off. TLB invalidation according to
> > unmapping on page tables must also be performed while power domain is
> > turned on.
> > 
> > This patch ensures that resume and runtime_resume(restore_state)
> > functions in this driver is called before the calls to resume and
> > runtime_resume callback functions in the drivers of master H/Ws.
> > Likewise, suspend and runtime_suspend(save_state) functions in this
> > driver is called after the calls to suspend and runtime_suspend in the
> > drivers of master H/Ws.
> > 
> > In order to get benefit of this support, the master H/W and its System
> > MMU must resides in the same power domain in terms of Linux kernel. If
> > a master H/W does not use generic I/O power domain, its driver must
> > call iommu_attach_device() after its local power domain is turned on,
> > iommu_detach_device before turned off.
> 
> I don't get the point of this last paragraph. What a power domain can be 
> in other terms? Is there any other way to support power domains on Exynos 
> than generic power domains?
> 

I just addressed the case a device driver turns off local power of its
device without the help of generic I/O powerdomain.

> > Signed-off-by: Cho KyongHo <pullip.cho@...sung.com>
> > ---
> >  drivers/iommu/exynos-iommu.c |  235
> > +++++++++++++++++++++++++++++++++++++++++- 1 files changed, 231
> > insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> > index 9e64483..56aead9 100644
> > --- a/drivers/iommu/exynos-iommu.c
> > +++ b/drivers/iommu/exynos-iommu.c
> > @@ -28,6 +28,7 @@
> >  #include <linux/export.h>
> >  #include <linux/of.h>
> >  #include <linux/of_platform.h>
> > +#include <linux/pm_domain.h>
> >  #include <linux/notifier.h>
> > 
> >  #include <asm/cacheflush.h>
> > @@ -186,6 +187,7 @@ struct sysmmu_drvdata {
> >  	int activations;
> >  	rwlock_t lock;
> >  	struct iommu_domain *domain;
> > +	bool runtime_active;
> >  	unsigned long pgtable;
> >  	void __iomem *sfrbases[0];
> >  };
> > @@ -438,7 +440,8 @@ static bool __sysmmu_disable(struct sysmmu_drvdata
> > *data) data->pgtable = 0;
> >  		data->domain = NULL;
> > 
> > -		__sysmmu_disable_nocount(data);
> > +		if (data->runtime_active)
> > +			__sysmmu_disable_nocount(data);
> > 
> >  		dev_dbg(data->sysmmu, "Disabled\n");
> >  	} else  {
> > @@ -505,7 +508,8 @@ static int __sysmmu_enable(struct sysmmu_drvdata
> > *data, data->pgtable = pgtable;
> >  		data->domain = domain;
> > 
> > -		__sysmmu_enable_nocount(data);
> > +		if (data->runtime_active)
> > +			__sysmmu_enable_nocount(data);
> > 
> >  		dev_dbg(data->sysmmu, "Enabled\n");
> >  	} else {
> > @@ -609,7 +613,7 @@ static void sysmmu_tlb_invalidate_entry(struct
> > device *dev, unsigned long iova) data =
> > dev_get_drvdata(client->sysmmu[i]);
> > 
> >  		read_lock_irqsave(&data->lock, flags);
> > -		if (is_sysmmu_active(data)) {
> > +		if (is_sysmmu_active(data) && data->runtime_active) {
> >  			int i;
> >  			clk_enable(data->clk_master);
> >  			for (i = 0; i < data->nsfrs; i++)
> > @@ -637,7 +641,8 @@ void exynos_sysmmu_tlb_invalidate(struct device
> > *dev) data = dev_get_drvdata(client->sysmmu[i]);
> > 
> >  		read_lock_irqsave(&data->lock, flags);
> > -		if (is_sysmmu_active(data)) {
> > +		if (is_sysmmu_active(data) &&
> > +				data->runtime_active) {
> 
> nit: The whole if condition fits into single line.

Ok.

> 
> >  			int i;
> >  			for (i = 0; i < data->nsfrs; i++) {
> >  				clk_enable(data->clk_master);
> > @@ -711,6 +716,8 @@ static int __init exynos_sysmmu_probe(struct
> > platform_device *pdev) }
> >  	}
> > 
> > +	pm_runtime_enable(dev);
> > +
> >  	data->sysmmu = dev;
> > 
> >  	data->clk = devm_clk_get(dev, "sysmmu");
> > @@ -736,6 +743,8 @@ static int __init exynos_sysmmu_probe(struct
> > platform_device *pdev) return ret;
> >  	}
> > 
> > +	data->runtime_active = !pm_runtime_enabled(dev);
> > +
> >  	rwlock_init(&data->lock);
> > 
> >  	platform_set_drvdata(pdev, data);
> > @@ -744,6 +753,34 @@ static int __init exynos_sysmmu_probe(struct
> > platform_device *pdev) return ret;
> >  }
> > 
> > +#ifdef CONFIG_PM_SLEEP
> > +static int sysmmu_suspend(struct device *dev)
> > +{
> > +	struct sysmmu_drvdata *data = dev_get_drvdata(dev);
> > +	unsigned long flags;
> > +	read_lock_irqsave(&data->lock, flags);
> > +	if (is_sysmmu_active(data) &&
> > +		(!pm_runtime_enabled(dev) || data->runtime_active))
> > +		__sysmmu_disable_nocount(data);
> > +	read_unlock_irqrestore(&data->lock, flags);
> > +	return 0;
> > +}
> > +
> > +static int sysmmu_resume(struct device *dev)
> > +{
> > +	struct sysmmu_drvdata *data = dev_get_drvdata(dev);
> > +	unsigned long flags;
> > +	read_lock_irqsave(&data->lock, flags);
> > +	if (is_sysmmu_active(data) &&
> > +		(!pm_runtime_enabled(dev) || data->runtime_active))
> > +		__sysmmu_enable_nocount(data);
> > +	read_unlock_irqrestore(&data->lock, flags);
> > +	return 0;
> > +}
> > +#endif
> > +
> > +static SIMPLE_DEV_PM_OPS(sysmmu_pm_ops, sysmmu_suspend, sysmmu_resume);
> > +
> >  #ifdef CONFIG_OF
> >  static struct of_device_id sysmmu_of_match[] __initconst = {
> >  	{ .compatible	= "samsung,exynos4210-sysmmu", },
> > @@ -756,6 +793,7 @@ static struct platform_driver exynos_sysmmu_driver
> > __refdata = { .driver	= {
> >  		.owner		= THIS_MODULE,
> >  		.name		= "exynos-sysmmu",
> > +		.pm		= &sysmmu_pm_ops,
> >  		.of_match_table	= of_match_ptr(sysmmu_of_match),
> >  	}
> >  };
> > @@ -1141,6 +1179,163 @@ static int __init exynos_iommu_init(void)
> >  }
> >  subsys_initcall(exynos_iommu_init);
> > 
> > +#ifdef CONFIG_PM_SLEEP
> > +static int sysmmu_pm_genpd_suspend(struct device *dev)
> > +{
> > +	struct exynos_iommu_client *client = dev->archdata.iommu;
> > +	int ret = 0;
> > +	int i;
> > +
> > +	for (i = 0; i < client->num_sysmmu; i++) {
> > +		ret = pm_generic_suspend(client->sysmmu[i]);
> > +		if (ret)
> > +			break;
> > +	}
> > +
> > +	if (!ret)
> > +		ret = pm_generic_suspend(dev);
> > +
> > +	if (ret) {
> > +		int j;
> > +
> > +		for (j = 0; j < i; j++)
> > +			pm_generic_resume(client->sysmmu[j]);
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> > +static int sysmmu_pm_genpd_resume(struct device *dev)
> > +{
> > +	struct exynos_iommu_client *client = dev->archdata.iommu;
> > +	int ret = 0;
> > +	int i;
> > +
> > +	for (i = 0; i < client->num_sysmmu; i++) {
> > +		ret = pm_generic_resume(client->sysmmu[i]);
> > +		if (ret)
> > +			break;
> 
> Error handling here can be cleaned up a lot.
> 
> s/break/goto err_suspend/
> 
> > +	}
> > +
> > +	if (!ret)
> 
> Now you can drop this check.
> 
> > +		ret = pm_generic_resume(dev);
> 
> 	ret = pm_generic_resume(dev);
> 	if (ret)
> 		goto err_suspend;
> 
> 	return 0;
> 
> > +
> 
> err_suspend:
> > +	if (ret) {
> 
> This check can be dropped here as well now.
> 

Ok.

Let me think about it :)

Thank you!

KyongHo.

> > +		int j;
> > +
> > +		for (j = 0; j < i; j++)
> > +			pm_generic_suspend(client->sysmmu[j]);
> > +	}
> > +
> > +	return ret;
> > +}
> > +#endif
> 
> Best regards,
> Tomasz
> 
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