[PATCH v4] mmc: add runtime and system power-management support to the MMCIF driver

[PATCH v4] mmc: add runtime and system power-management support to the MMCIF driver

[Guennadi Liakhovetski]

Adding support for runtime power-management to the MMCIF driver allows
it to save power as long as no card is present. To also allow to turn
off the power domain at that time, we release DMA channels during that
time, since on some sh-mobile systems the DMA controller(s) and the
MMCIF block belong to the same power domain. System-wide power
management has been tested with experimental PM patches on AP4-based
systems.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
---

This patch supersedes:

[PATCH 2/3 v3] MMC: add runtime and system power-management support to the MMCIF driver

and has been tested to work with Rafael's suspend git-tree, power-domains 
branch.

 drivers/mmc/host/sh_mmcif.c |   78 ++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 69 insertions(+), 9 deletions(-)

diff --git a/drivers/mmc/host/sh_mmcif.c b/drivers/mmc/host/sh_mmcif.c
index d3871b6..14f8edb 100644
--- a/drivers/mmc/host/sh_mmcif.c
+++ b/drivers/mmc/host/sh_mmcif.c
@@ -29,6 +29,7 @@
 #include <linux/mmc/sh_mmcif.h>
 #include <linux/pagemap.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/spinlock.h>
 
 #define DRIVER_NAME	"sh_mmcif"
@@ -173,6 +174,7 @@ struct sh_mmcif_host {
 	struct completion intr_wait;
 	enum mmcif_state state;
 	spinlock_t lock;
+	bool power;
 
 	/* DMA support */
 	struct dma_chan		*chan_rx;
@@ -877,11 +879,24 @@ static void sh_mmcif_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 	if (ios->power_mode == MMC_POWER_UP) {
 		if (p->set_pwr)
 			p->set_pwr(host->pd, ios->power_mode);
+		if (!host->power) {
+			/* See if we also get DMA */
+			sh_mmcif_request_dma(host, host->pd->dev.platform_data);
+			pm_runtime_get_sync(&host->pd->dev);
+			host->power = true;
+		}
 	} else if (ios->power_mode == MMC_POWER_OFF || !ios->clock) {
 		/* clock stop */
 		sh_mmcif_clock_control(host, 0);
-		if (ios->power_mode == MMC_POWER_OFF && p->down_pwr)
-			p->down_pwr(host->pd);
+		if (ios->power_mode == MMC_POWER_OFF) {
+			if (host->power) {
+				pm_runtime_put(&host->pd->dev);
+				sh_mmcif_release_dma(host);
+				host->power = false;
+			}
+			if (p->down_pwr)
+				p->down_pwr(host->pd);
+		}
 		host->state = STATE_IDLE;
 		return;
 	}
@@ -957,7 +972,7 @@ static irqreturn_t sh_mmcif_intr(int irq, void *dev_id)
 		sh_mmcif_bitclr(host, MMCIF_CE_INT_MASK, state);
 		err = 1;
 	} else {
-		dev_dbg(&host->pd->dev, "Not support int\n");
+		dev_dbg(&host->pd->dev, "Unsupported interrupt: 0x%x\n", state);
 		sh_mmcif_writel(host->addr, MMCIF_CE_INT, ~state);
 		sh_mmcif_bitclr(host, MMCIF_CE_INT_MASK, state);
 		err = 1;
@@ -1053,8 +1068,12 @@ static int __devinit sh_mmcif_probe(struct platform_device *pdev)
 	sh_mmcif_sync_reset(host);
 	platform_set_drvdata(pdev, host);
 
-	/* See if we also get DMA */
-	sh_mmcif_request_dma(host, pd);
+	pm_runtime_enable(&pdev->dev);
+	host->power = false;
+
+	ret = pm_runtime_resume(&pdev->dev);
+	if (ret < 0)
+		goto clean_up2;
 
 	mmc_add_host(mmc);
 
@@ -1063,13 +1082,13 @@ static int __devinit sh_mmcif_probe(struct platform_device *pdev)
 	ret = request_irq(irq[0], sh_mmcif_intr, 0, "sh_mmc:error", host);
 	if (ret) {
 		dev_err(&pdev->dev, "request_irq error (sh_mmc:error)\n");
-		goto clean_up2;
+		goto clean_up3;
 	}
 	ret = request_irq(irq[1], sh_mmcif_intr, 0, "sh_mmc:int", host);
 	if (ret) {
 		free_irq(irq[0], host);
 		dev_err(&pdev->dev, "request_irq error (sh_mmc:int)\n");
-		goto clean_up2;
+		goto clean_up3;
 	}
 
 	sh_mmcif_detect(host->mmc);
@@ -1079,7 +1098,11 @@ static int __devinit sh_mmcif_probe(struct platform_device *pdev)
 		sh_mmcif_readl(host->addr, MMCIF_CE_VERSION) & 0x0000ffff);
 	return ret;
 
+clean_up3:
+	mmc_remove_host(mmc);
+	pm_runtime_suspend(&pdev->dev);
 clean_up2:
+	pm_runtime_disable(&pdev->dev);
 	clk_disable(host->hclk);
 clean_up1:
 	mmc_free_host(mmc);
@@ -1094,9 +1117,9 @@ static int __devexit sh_mmcif_remove(struct platform_device *pdev)
 	struct sh_mmcif_host *host = platform_get_drvdata(pdev);
 	int irq[2];
 
-	mmc_remove_host(host->mmc);
-	sh_mmcif_release_dma(host);
+	pm_runtime_get_sync(&pdev->dev);
 
+	mmc_remove_host(host->mmc);
 	sh_mmcif_writel(host->addr, MMCIF_CE_INT_MASK, MASK_ALL);
 
 	if (host->addr)
@@ -1112,15 +1135,52 @@ static int __devexit sh_mmcif_remove(struct platform_device *pdev)
 
 	clk_disable(host->hclk);
 	mmc_free_host(host->mmc);
+	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
 
 	return 0;
 }
 
+#ifdef CONFIG_PM
+static int sh_mmcif_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct sh_mmcif_host *host = platform_get_drvdata(pdev);
+	int ret = mmc_suspend_host(host->mmc);
+
+	if (!ret) {
+		sh_mmcif_writel(host->addr, MMCIF_CE_INT_MASK, MASK_ALL);
+		clk_disable(host->hclk);
+	}
+
+	return ret;
+}
+
+static int sh_mmcif_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct sh_mmcif_host *host = platform_get_drvdata(pdev);
+
+	clk_enable(host->hclk);
+
+	return mmc_resume_host(host->mmc);
+}
+#else
+#define sh_mmcif_suspend	NULL
+#define sh_mmcif_resume		NULL
+#endif	/* CONFIG_PM */
+
+static const struct dev_pm_ops sh_mmcif_dev_pm_ops = {
+	.suspend = sh_mmcif_suspend,
+	.resume = sh_mmcif_resume,
+};
+
 static struct platform_driver sh_mmcif_driver = {
 	.probe		= sh_mmcif_probe,
 	.remove		= sh_mmcif_remove,
 	.driver		= {
 		.name	= DRIVER_NAME,
+		.pm	= &sh_mmcif_dev_pm_ops,
 	},
 };
 
-- 
1.7.2.5

Re: [PATCH v4] mmc: add runtime and system power-management support to the MMCIF driver

[Rafael J. Wysocki]

On Thursday, May 05, 2011, Guennadi Liakhovetski wrote:
> Adding support for runtime power-management to the MMCIF driver allows
> it to save power as long as no card is present. To also allow to turn
> off the power domain at that time, we release DMA channels during that
> time, since on some sh-mobile systems the DMA controller(s) and the
> MMCIF block belong to the same power domain. System-wide power
> management has been tested with experimental PM patches on AP4-based
> systems.
> 
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> ---
> 
> This patch supersedes:
> 
> [PATCH 2/3 v3] MMC: add runtime and system power-management support to the MMCIF driver
> 
> and has been tested to work with Rafael's suspend git-tree, power-domains 
> branch.
> 
>  drivers/mmc/host/sh_mmcif.c |   78 ++++++++++++++++++++++++++++++++++++++-----
>  1 files changed, 69 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/mmc/host/sh_mmcif.c b/drivers/mmc/host/sh_mmcif.c
> index d3871b6..14f8edb 100644
> --- a/drivers/mmc/host/sh_mmcif.c
> +++ b/drivers/mmc/host/sh_mmcif.c
> @@ -29,6 +29,7 @@
>  #include <linux/mmc/sh_mmcif.h>
>  #include <linux/pagemap.h>
>  #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/spinlock.h>
>  
>  #define DRIVER_NAME	"sh_mmcif"
> @@ -173,6 +174,7 @@ struct sh_mmcif_host {
>  	struct completion intr_wait;
>  	enum mmcif_state state;
>  	spinlock_t lock;
> +	bool power;
>  
>  	/* DMA support */
>  	struct dma_chan		*chan_rx;
> @@ -877,11 +879,24 @@ static void sh_mmcif_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>  	if (ios->power_mode == MMC_POWER_UP) {
>  		if (p->set_pwr)
>  			p->set_pwr(host->pd, ios->power_mode);
> +		if (!host->power) {
> +			/* See if we also get DMA */
> +			sh_mmcif_request_dma(host, host->pd->dev.platform_data);
> +			pm_runtime_get_sync(&host->pd->dev);
> +			host->power = true;
> +		}
>  	} else if (ios->power_mode == MMC_POWER_OFF || !ios->clock) {
>  		/* clock stop */
>  		sh_mmcif_clock_control(host, 0);
> -		if (ios->power_mode == MMC_POWER_OFF && p->down_pwr)
> -			p->down_pwr(host->pd);
> +		if (ios->power_mode == MMC_POWER_OFF) {
> +			if (host->power) {
> +				pm_runtime_put(&host->pd->dev);
> +				sh_mmcif_release_dma(host);
> +				host->power = false;
> +			}
> +			if (p->down_pwr)
> +				p->down_pwr(host->pd);
> +		}
>  		host->state = STATE_IDLE;
>  		return;
>  	}
> @@ -957,7 +972,7 @@ static irqreturn_t sh_mmcif_intr(int irq, void *dev_id)
>  		sh_mmcif_bitclr(host, MMCIF_CE_INT_MASK, state);
>  		err = 1;
>  	} else {
> -		dev_dbg(&host->pd->dev, "Not support int\n");
> +		dev_dbg(&host->pd->dev, "Unsupported interrupt: 0x%x\n", state);
>  		sh_mmcif_writel(host->addr, MMCIF_CE_INT, ~state);
>  		sh_mmcif_bitclr(host, MMCIF_CE_INT_MASK, state);
>  		err = 1;
> @@ -1053,8 +1068,12 @@ static int __devinit sh_mmcif_probe(struct platform_device *pdev)
>  	sh_mmcif_sync_reset(host);
>  	platform_set_drvdata(pdev, host);
>  
> -	/* See if we also get DMA */
> -	sh_mmcif_request_dma(host, pd);
> +	pm_runtime_enable(&pdev->dev);
> +	host->power = false;
> +
> +	ret = pm_runtime_resume(&pdev->dev);
> +	if (ret < 0)
> +		goto clean_up2;
>  
>  	mmc_add_host(mmc);
>  
> @@ -1063,13 +1082,13 @@ static int __devinit sh_mmcif_probe(struct platform_device *pdev)
>  	ret = request_irq(irq[0], sh_mmcif_intr, 0, "sh_mmc:error", host);
>  	if (ret) {
>  		dev_err(&pdev->dev, "request_irq error (sh_mmc:error)\n");
> -		goto clean_up2;
> +		goto clean_up3;
>  	}
>  	ret = request_irq(irq[1], sh_mmcif_intr, 0, "sh_mmc:int", host);
>  	if (ret) {
>  		free_irq(irq[0], host);
>  		dev_err(&pdev->dev, "request_irq error (sh_mmc:int)\n");
> -		goto clean_up2;
> +		goto clean_up3;
>  	}
>  
>  	sh_mmcif_detect(host->mmc);
> @@ -1079,7 +1098,11 @@ static int __devinit sh_mmcif_probe(struct platform_device *pdev)
>  		sh_mmcif_readl(host->addr, MMCIF_CE_VERSION) & 0x0000ffff);
>  	return ret;
>  
> +clean_up3:
> +	mmc_remove_host(mmc);
> +	pm_runtime_suspend(&pdev->dev);
>  clean_up2:
> +	pm_runtime_disable(&pdev->dev);
>  	clk_disable(host->hclk);
>  clean_up1:
>  	mmc_free_host(mmc);
> @@ -1094,9 +1117,9 @@ static int __devexit sh_mmcif_remove(struct platform_device *pdev)
>  	struct sh_mmcif_host *host = platform_get_drvdata(pdev);
>  	int irq[2];
>  
> -	mmc_remove_host(host->mmc);
> -	sh_mmcif_release_dma(host);
> +	pm_runtime_get_sync(&pdev->dev);
>  
> +	mmc_remove_host(host->mmc);
>  	sh_mmcif_writel(host->addr, MMCIF_CE_INT_MASK, MASK_ALL);
>  
>  	if (host->addr)
> @@ -1112,15 +1135,52 @@ static int __devexit sh_mmcif_remove(struct platform_device *pdev)
>  
>  	clk_disable(host->hclk);
>  	mmc_free_host(host->mmc);
> +	pm_runtime_put_sync(&pdev->dev);
> +	pm_runtime_disable(&pdev->dev);
>  
>  	return 0;
>  }
>  
> +#ifdef CONFIG_PM
> +static int sh_mmcif_suspend(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct sh_mmcif_host *host = platform_get_drvdata(pdev);
> +	int ret = mmc_suspend_host(host->mmc);
> +
> +	if (!ret) {
> +		sh_mmcif_writel(host->addr, MMCIF_CE_INT_MASK, MASK_ALL);
> +		clk_disable(host->hclk);
> +	}
> +
> +	return ret;
> +}
> +
> +static int sh_mmcif_resume(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct sh_mmcif_host *host = platform_get_drvdata(pdev);
> +
> +	clk_enable(host->hclk);
> +
> +	return mmc_resume_host(host->mmc);
> +}
> +#else
> +#define sh_mmcif_suspend	NULL
> +#define sh_mmcif_resume		NULL
> +#endif	/* CONFIG_PM */
> +
> +static const struct dev_pm_ops sh_mmcif_dev_pm_ops = {
> +	.suspend = sh_mmcif_suspend,
> +	.resume = sh_mmcif_resume,
> +};

So this means the driver only has system-wide suspend/resume callbacks.
I guess hibernation is not supported by the target platform(s) yet, so
the freeze/thaw etc. callbacks are not necessary at the moment, but in case
they are supposed to be the same as the suspend/resume ones, it wouldn't
hurt to use SET_SYSTEM_SLEEP_PM_OPS (as defined in include/linux/pm.h).

Also, runtime PM callbacks are not present.  Is it intentional?  I thought
they would be necessary to save/restore the device state over the power
domain power down/power up, wouldn't they?

> +
>  static struct platform_driver sh_mmcif_driver = {
>  	.probe		= sh_mmcif_probe,
>  	.remove		= sh_mmcif_remove,
>  	.driver		= {
>  		.name	= DRIVER_NAME,
> +		.pm	= &sh_mmcif_dev_pm_ops,
>  	},
>  };

Thanks,
Rafael

Re: [PATCH v4] mmc: add runtime and system power-management support to the MMCIF driver

[Guennadi Liakhovetski]

On Thu, 5 May 2011, Rafael J. Wysocki wrote:

> On Thursday, May 05, 2011, Guennadi Liakhovetski wrote:
> > Adding support for runtime power-management to the MMCIF driver allows
> > it to save power as long as no card is present. To also allow to turn
> > off the power domain at that time, we release DMA channels during that
> > time, since on some sh-mobile systems the DMA controller(s) and the
> > MMCIF block belong to the same power domain. System-wide power
> > management has been tested with experimental PM patches on AP4-based
> > systems.
> > 
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> > ---
> > 
> > This patch supersedes:
> > 
> > [PATCH 2/3 v3] MMC: add runtime and system power-management support to the MMCIF driver
> > 
> > and has been tested to work with Rafael's suspend git-tree, power-domains 
> > branch.
> > 
> >  drivers/mmc/host/sh_mmcif.c |   78 ++++++++++++++++++++++++++++++++++++++-----
> >  1 files changed, 69 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/mmc/host/sh_mmcif.c b/drivers/mmc/host/sh_mmcif.c
> > index d3871b6..14f8edb 100644
> > --- a/drivers/mmc/host/sh_mmcif.c
> > +++ b/drivers/mmc/host/sh_mmcif.c

[snip]

> > @@ -1112,15 +1135,52 @@ static int __devexit sh_mmcif_remove(struct platform_device *pdev)
> >  
> >  	clk_disable(host->hclk);
> >  	mmc_free_host(host->mmc);
> > +	pm_runtime_put_sync(&pdev->dev);
> > +	pm_runtime_disable(&pdev->dev);
> >  
> >  	return 0;
> >  }
> >  
> > +#ifdef CONFIG_PM
> > +static int sh_mmcif_suspend(struct device *dev)
> > +{
> > +	struct platform_device *pdev = to_platform_device(dev);
> > +	struct sh_mmcif_host *host = platform_get_drvdata(pdev);
> > +	int ret = mmc_suspend_host(host->mmc);
> > +
> > +	if (!ret) {
> > +		sh_mmcif_writel(host->addr, MMCIF_CE_INT_MASK, MASK_ALL);
> > +		clk_disable(host->hclk);
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> > +static int sh_mmcif_resume(struct device *dev)
> > +{
> > +	struct platform_device *pdev = to_platform_device(dev);
> > +	struct sh_mmcif_host *host = platform_get_drvdata(pdev);
> > +
> > +	clk_enable(host->hclk);
> > +
> > +	return mmc_resume_host(host->mmc);
> > +}
> > +#else
> > +#define sh_mmcif_suspend	NULL
> > +#define sh_mmcif_resume		NULL
> > +#endif	/* CONFIG_PM */
> > +
> > +static const struct dev_pm_ops sh_mmcif_dev_pm_ops = {
> > +	.suspend = sh_mmcif_suspend,
> > +	.resume = sh_mmcif_resume,
> > +};
> 
> So this means the driver only has system-wide suspend/resume callbacks.
> I guess hibernation is not supported by the target platform(s) yet, so
> the freeze/thaw etc. callbacks are not necessary at the moment, but in case
> they are supposed to be the same as the suspend/resume ones, it wouldn't
> hurt to use SET_SYSTEM_SLEEP_PM_OPS (as defined in include/linux/pm.h).

Hm, I've tested this with experimental STR patches from Magnus. He has 
also sent some patches for that to the ML a week ago. So, not sure I need 
SET_SYSTEM_SLEEP_PM_OPS.

> Also, runtime PM callbacks are not present.  Is it intentional?  I thought
> they would be necessary to save/restore the device state over the power
> domain power down/power up, wouldn't they?

This is intentional. We only allow runtime suspend with no cards plugged 
in, and then there isn't much to save and restore there, on each new card 
insertion a complete initialisation is taking place anyway.

> > +
> >  static struct platform_driver sh_mmcif_driver = {
> >  	.probe		= sh_mmcif_probe,
> >  	.remove		= sh_mmcif_remove,
> >  	.driver		= {
> >  		.name	= DRIVER_NAME,
> > +		.pm	= &sh_mmcif_dev_pm_ops,
> >  	},
> >  };
> 
> Thanks,
> Rafael

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/

Re: [PATCH v4] mmc: add runtime and system power-management support to the MMCIF driver

[Rafael J. Wysocki]

On Friday, May 06, 2011, Guennadi Liakhovetski wrote:
> On Thu, 5 May 2011, Rafael J. Wysocki wrote:
> 
> > On Thursday, May 05, 2011, Guennadi Liakhovetski wrote:
> > > Adding support for runtime power-management to the MMCIF driver allows
> > > it to save power as long as no card is present. To also allow to turn
> > > off the power domain at that time, we release DMA channels during that
> > > time, since on some sh-mobile systems the DMA controller(s) and the
> > > MMCIF block belong to the same power domain. System-wide power
> > > management has been tested with experimental PM patches on AP4-based
> > > systems.
> > > 
> > > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> > > ---
> > > 
> > > This patch supersedes:
> > > 
> > > [PATCH 2/3 v3] MMC: add runtime and system power-management support to the MMCIF driver
> > > 
> > > and has been tested to work with Rafael's suspend git-tree, power-domains 
> > > branch.
> > > 
> > >  drivers/mmc/host/sh_mmcif.c |   78 ++++++++++++++++++++++++++++++++++++++-----
> > >  1 files changed, 69 insertions(+), 9 deletions(-)
> > > 
> > > diff --git a/drivers/mmc/host/sh_mmcif.c b/drivers/mmc/host/sh_mmcif.c
> > > index d3871b6..14f8edb 100644
> > > --- a/drivers/mmc/host/sh_mmcif.c
> > > +++ b/drivers/mmc/host/sh_mmcif.c
> 
> [snip]
> 
> > > @@ -1112,15 +1135,52 @@ static int __devexit sh_mmcif_remove(struct platform_device *pdev)
> > >  
> > >  	clk_disable(host->hclk);
> > >  	mmc_free_host(host->mmc);
> > > +	pm_runtime_put_sync(&pdev->dev);
> > > +	pm_runtime_disable(&pdev->dev);
> > >  
> > >  	return 0;
> > >  }
> > >  
> > > +#ifdef CONFIG_PM
> > > +static int sh_mmcif_suspend(struct device *dev)
> > > +{
> > > +	struct platform_device *pdev = to_platform_device(dev);
> > > +	struct sh_mmcif_host *host = platform_get_drvdata(pdev);
> > > +	int ret = mmc_suspend_host(host->mmc);
> > > +
> > > +	if (!ret) {
> > > +		sh_mmcif_writel(host->addr, MMCIF_CE_INT_MASK, MASK_ALL);
> > > +		clk_disable(host->hclk);
> > > +	}
> > > +
> > > +	return ret;
> > > +}
> > > +
> > > +static int sh_mmcif_resume(struct device *dev)
> > > +{
> > > +	struct platform_device *pdev = to_platform_device(dev);
> > > +	struct sh_mmcif_host *host = platform_get_drvdata(pdev);
> > > +
> > > +	clk_enable(host->hclk);
> > > +
> > > +	return mmc_resume_host(host->mmc);
> > > +}
> > > +#else
> > > +#define sh_mmcif_suspend	NULL
> > > +#define sh_mmcif_resume		NULL
> > > +#endif	/* CONFIG_PM */
> > > +
> > > +static const struct dev_pm_ops sh_mmcif_dev_pm_ops = {
> > > +	.suspend = sh_mmcif_suspend,
> > > +	.resume = sh_mmcif_resume,
> > > +};
> > 
> > So this means the driver only has system-wide suspend/resume callbacks.
> > I guess hibernation is not supported by the target platform(s) yet, so
> > the freeze/thaw etc. callbacks are not necessary at the moment, but in case
> > they are supposed to be the same as the suspend/resume ones, it wouldn't
> > hurt to use SET_SYSTEM_SLEEP_PM_OPS (as defined in include/linux/pm.h).
> 
> Hm, I've tested this with experimental STR patches from Magnus. He has 
> also sent some patches for that to the ML a week ago. So, not sure I need 
> SET_SYSTEM_SLEEP_PM_OPS.

You may not need it right now, but it comes basically without a cost and
the benefit is that people will know what the hibernate callbacks are
supposed to be (in case somebody attempts to implement hibernation on your
target platform(s)).

> > Also, runtime PM callbacks are not present.  Is it intentional?  I thought
> > they would be necessary to save/restore the device state over the power
> > domain power down/power up, wouldn't they?
> 
> This is intentional. We only allow runtime suspend with no cards plugged 
> in, and then there isn't much to save and restore there, on each new card 
> insertion a complete initialisation is taking place anyway.

OK then.

Thanks,
Rafael