[PATCH] spi/atmel: add support for runtime PM

[PATCH] spi/atmel: add support for runtime PM

[Wenyou Yang]

Drivers should put the device into low power states proactively whenever the
device is not in use. Thus implement support for runtime PM and use the
autosuspend feature to make sure that we can still perform well in case we see
lots of SPI traffic within short period of time.

Signed-off-by: Wenyou Yang <wenyou.yang-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
---
 drivers/spi/spi-atmel.c |   62 +++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 55 insertions(+), 7 deletions(-)

diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index 649dcb5..aca285e 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -26,6 +26,7 @@
 #include <linux/io.h>
 #include <linux/gpio.h>
 #include <linux/pinctrl/consumer.h>
+#include <linux/pm_runtime.h>
 
 /* SPI register offsets */
 #define SPI_CR					0x0000
@@ -191,6 +192,8 @@
 
 #define SPI_DMA_TIMEOUT		(msecs_to_jiffies(1000))
 
+#define AUTOSUSPEND_TIMEOUT	2000
+
 struct atmel_spi_dma {
 	struct dma_chan			*chan_rx;
 	struct dma_chan			*chan_tx;
@@ -1313,6 +1316,7 @@ static int atmel_spi_probe(struct platform_device *pdev)
 	master->setup = atmel_spi_setup;
 	master->transfer_one_message = atmel_spi_transfer_one_message;
 	master->cleanup = atmel_spi_cleanup;
+	master->auto_runtime_pm = true;
 	platform_set_drvdata(pdev, master);
 
 	as = spi_master_get_devdata(master);
@@ -1385,6 +1389,11 @@ static int atmel_spi_probe(struct platform_device *pdev)
 	dev_info(&pdev->dev, "Atmel SPI Controller at 0x%08lx (irq %d)\n",
 			(unsigned long)regs->start, irq);
 
+	pm_runtime_set_autosuspend_delay(&pdev->dev, AUTOSUSPEND_TIMEOUT);
+	pm_runtime_use_autosuspend(&pdev->dev);
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+
 	ret = devm_spi_register_master(&pdev->dev, master);
 	if (ret)
 		goto out_free_dma;
@@ -1392,6 +1401,9 @@ static int atmel_spi_probe(struct platform_device *pdev)
 	return 0;
 
 out_free_dma:
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
+
 	if (as->use_dma)
 		atmel_spi_release_dma(as);
 
@@ -1413,6 +1425,8 @@ static int atmel_spi_remove(struct platform_device *pdev)
 	struct spi_master	*master = platform_get_drvdata(pdev);
 	struct atmel_spi	*as = spi_master_get_devdata(master);
 
+	pm_runtime_get_sync(&pdev->dev);
+
 	/* reset the hardware and block queue progress */
 	spin_lock_irq(&as->lock);
 	if (as->use_dma) {
@@ -1430,9 +1444,13 @@ static int atmel_spi_remove(struct platform_device *pdev)
 
 	clk_disable_unprepare(as->clk);
 
+	pm_runtime_put_noidle(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+
 	return 0;
 }
 
+#ifdef CONFIG_PM
 #ifdef CONFIG_PM_SLEEP
 static int atmel_spi_suspend(struct device *dev)
 {
@@ -1447,9 +1465,10 @@ static int atmel_spi_suspend(struct device *dev)
 		return ret;
 	}
 
-	clk_disable_unprepare(as->clk);
-
-	pinctrl_pm_select_sleep_state(dev);
+	if (!pm_runtime_suspended(dev)) {
+		clk_disable_unprepare(as->clk);
+		pinctrl_pm_select_sleep_state(dev);
+	}
 
 	return 0;
 }
@@ -1460,9 +1479,10 @@ static int atmel_spi_resume(struct device *dev)
 	struct atmel_spi	*as = spi_master_get_devdata(master);
 	int ret;
 
-	pinctrl_pm_select_default_state(dev);
-
-	clk_prepare_enable(as->clk);
+	if (!pm_runtime_suspended(dev)) {
+		pinctrl_pm_select_default_state(dev);
+		clk_prepare_enable(as->clk);
+	}
 
 	/* Start the queue running */
 	ret = spi_master_resume(master);
@@ -1471,9 +1491,37 @@ static int atmel_spi_resume(struct device *dev)
 
 	return ret;
 }
+#endif
 
-static SIMPLE_DEV_PM_OPS(atmel_spi_pm_ops, atmel_spi_suspend, atmel_spi_resume);
+#ifdef CONFIG_PM_RUNTIME
+static int atmel_spi_runtime_suspend(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct atmel_spi *as = spi_master_get_devdata(master);
 
+	clk_disable_unprepare(as->clk);
+	pinctrl_pm_select_sleep_state(dev);
+
+	return 0;
+}
+
+static int atmel_spi_runtime_resume(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct atmel_spi *as = spi_master_get_devdata(master);
+
+	pinctrl_pm_select_default_state(dev);
+	clk_prepare_enable(as->clk);
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops atmel_spi_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(atmel_spi_suspend, atmel_spi_resume)
+	SET_RUNTIME_PM_OPS(atmel_spi_runtime_suspend,
+			   atmel_spi_runtime_resume, NULL)
+};
 #define ATMEL_SPI_PM_OPS	(&atmel_spi_pm_ops)
 #else
 #define ATMEL_SPI_PM_OPS	NULL
-- 
1.7.9.5

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Re: [PATCH] spi/atmel: add support for runtime PM

[Mark Brown]

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On Thu, Oct 16, 2014 at 09:49:20AM +0800, Wenyou Yang wrote:

> +static int atmel_spi_runtime_resume(struct device *dev)
> +{
> +	struct spi_master *master = dev_get_drvdata(dev);
> +	struct atmel_spi *as = spi_master_get_devdata(master);
> +
> +	pinctrl_pm_select_default_state(dev);
> +	clk_prepare_enable(as->clk);
> +

This looks mostly good but you should check the return value of
clk_prepare_enable() - it can fail.

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RE: [PATCH] spi/atmel: add support for runtime PM

[Yang, Wenyou]

Hi Mark,

> -----Original Message-----
> From: Mark Brown [mailto:broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org]
> Sent: Thursday, October 16, 2014 3:30 PM
> To: Yang, Wenyou
> Cc: linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Ferre, Nicolas; linux-
> arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
> Subject: Re: [PATCH] spi/atmel: add support for runtime PM
> 
> On Thu, Oct 16, 2014 at 09:49:20AM +0800, Wenyou Yang wrote:
> 
> > +static int atmel_spi_runtime_resume(struct device *dev) {
> > +	struct spi_master *master = dev_get_drvdata(dev);
> > +	struct atmel_spi *as = spi_master_get_devdata(master);
> > +
> > +	pinctrl_pm_select_default_state(dev);
> > +	clk_prepare_enable(as->clk);
> > +
> 
> This looks mostly good but you should check the return value of
> clk_prepare_enable() - it can fail.
Thanks a lot, I will add it.

Best Regards,
Wenyou Yang
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Re: [PATCH] spi/atmel: add support for runtime PM

[Kevin Hilman]

Wenyou Yang <wenyou.yang@atmel.com> writes:

> Drivers should put the device into low power states proactively whenever the
> device is not in use. Thus implement support for runtime PM and use the
> autosuspend feature to make sure that we can still perform well in case we see
> lots of SPI traffic within short period of time.
>
> Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
> ---
>  drivers/spi/spi-atmel.c |   62 +++++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 55 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
> index 649dcb5..aca285e 100644
> --- a/drivers/spi/spi-atmel.c
> +++ b/drivers/spi/spi-atmel.c
> @@ -26,6 +26,7 @@
>  #include <linux/io.h>
>  #include <linux/gpio.h>
>  #include <linux/pinctrl/consumer.h>
> +#include <linux/pm_runtime.h>
>  
>  /* SPI register offsets */
>  #define SPI_CR					0x0000
> @@ -191,6 +192,8 @@
>  
>  #define SPI_DMA_TIMEOUT		(msecs_to_jiffies(1000))
>  
> +#define AUTOSUSPEND_TIMEOUT	2000
> +
>  struct atmel_spi_dma {
>  	struct dma_chan			*chan_rx;
>  	struct dma_chan			*chan_tx;
> @@ -1313,6 +1316,7 @@ static int atmel_spi_probe(struct platform_device *pdev)
>  	master->setup = atmel_spi_setup;
>  	master->transfer_one_message = atmel_spi_transfer_one_message;
>  	master->cleanup = atmel_spi_cleanup;
> +	master->auto_runtime_pm = true;
>  	platform_set_drvdata(pdev, master);
>  
>  	as = spi_master_get_devdata(master);
> @@ -1385,6 +1389,11 @@ static int atmel_spi_probe(struct platform_device *pdev)
>  	dev_info(&pdev->dev, "Atmel SPI Controller at 0x%08lx (irq %d)\n",
>  			(unsigned long)regs->start, irq);
>  
> +	pm_runtime_set_autosuspend_delay(&pdev->dev, AUTOSUSPEND_TIMEOUT);
> +	pm_runtime_use_autosuspend(&pdev->dev);
> +	pm_runtime_set_active(&pdev->dev);
> +	pm_runtime_enable(&pdev->dev);
> +
>  	ret = devm_spi_register_master(&pdev->dev, master);
>  	if (ret)
>  		goto out_free_dma;
> @@ -1392,6 +1401,9 @@ static int atmel_spi_probe(struct platform_device *pdev)
>  	return 0;
>  
>  out_free_dma:
> +	pm_runtime_disable(&pdev->dev);
> +	pm_runtime_set_suspended(&pdev->dev);
> +
>  	if (as->use_dma)
>  		atmel_spi_release_dma(as);
>  
> @@ -1413,6 +1425,8 @@ static int atmel_spi_remove(struct platform_device *pdev)
>  	struct spi_master	*master = platform_get_drvdata(pdev);
>  	struct atmel_spi	*as = spi_master_get_devdata(master);
>  
> +	pm_runtime_get_sync(&pdev->dev);
> +
>  	/* reset the hardware and block queue progress */
>  	spin_lock_irq(&as->lock);
>  	if (as->use_dma) {
> @@ -1430,9 +1444,13 @@ static int atmel_spi_remove(struct platform_device *pdev)
>  
>  	clk_disable_unprepare(as->clk);
>  
> +	pm_runtime_put_noidle(&pdev->dev);

Why the _noidle version?

> +	pm_runtime_disable(&pdev->dev);
> +
>  	return 0;
>  }
>  
> +#ifdef CONFIG_PM

Why CONFIG_PM?  CONFIG_PM_SLEEP  causes CONFIG_PM=y, so this seems
redundant.

>  #ifdef CONFIG_PM_SLEEP
>  static int atmel_spi_suspend(struct device *dev)
>  {
> @@ -1447,9 +1465,10 @@ static int atmel_spi_suspend(struct device *dev)
>  		return ret;
>  	}
>  
> -	clk_disable_unprepare(as->clk);
> -
> -	pinctrl_pm_select_sleep_state(dev);
> +	if (!pm_runtime_suspended(dev)) {
> +		clk_disable_unprepare(as->clk);
> +		pinctrl_pm_select_sleep_state(dev);
> +	}

a.k.a. pm_runtime_put_sync() since the ->runtime_suspend() callback does
the same thing.

>  	return 0;
>  }
> @@ -1460,9 +1479,10 @@ static int atmel_spi_resume(struct device *dev)
>  	struct atmel_spi	*as = spi_master_get_devdata(master);
>  	int ret;
>  
> -	pinctrl_pm_select_default_state(dev);
> -
> -	clk_prepare_enable(as->clk);
> +	if (!pm_runtime_suspended(dev)) {
> +		pinctrl_pm_select_default_state(dev);
> +		clk_prepare_enable(as->clk);
> +	}

a.k.a. pm_runtime_get_sync()

Kevin

>  	/* Start the queue running */
>  	ret = spi_master_resume(master);
> @@ -1471,9 +1491,37 @@ static int atmel_spi_resume(struct device *dev)
>  
>  	return ret;
>  }
> +#endif
>  
> -static SIMPLE_DEV_PM_OPS(atmel_spi_pm_ops, atmel_spi_suspend, atmel_spi_resume);
> +#ifdef CONFIG_PM_RUNTIME
> +static int atmel_spi_runtime_suspend(struct device *dev)
> +{
> +	struct spi_master *master = dev_get_drvdata(dev);
> +	struct atmel_spi *as = spi_master_get_devdata(master);
>  
> +	clk_disable_unprepare(as->clk);
> +	pinctrl_pm_select_sleep_state(dev);
> +
> +	return 0;
> +}
> +
> +static int atmel_spi_runtime_resume(struct device *dev)
> +{
> +	struct spi_master *master = dev_get_drvdata(dev);
> +	struct atmel_spi *as = spi_master_get_devdata(master);
> +
> +	pinctrl_pm_select_default_state(dev);
> +	clk_prepare_enable(as->clk);
> +
> +	return 0;
> +}
> +#endif
> +
> +static const struct dev_pm_ops atmel_spi_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(atmel_spi_suspend, atmel_spi_resume)
> +	SET_RUNTIME_PM_OPS(atmel_spi_runtime_suspend,
> +			   atmel_spi_runtime_resume, NULL)
> +};
>  #define ATMEL_SPI_PM_OPS	(&atmel_spi_pm_ops)
>  #else
>  #define ATMEL_SPI_PM_OPS	NULL

Re: [PATCH] spi/atmel: add support for runtime PM

[Mark Brown]

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On Fri, Oct 17, 2014 at 06:02:35AM -0700, Kevin Hilman wrote:
> Wenyou Yang <wenyou.yang@atmel.com> writes:

> > +	if (!pm_runtime_suspended(dev)) {
> > +		clk_disable_unprepare(as->clk);
> > +		pinctrl_pm_select_sleep_state(dev);
> > +	}

> a.k.a. pm_runtime_put_sync() since the ->runtime_suspend() callback does
> the same thing.

Will that do the right thing when runtime PM is disabled in Kconfig?

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Re: [PATCH] spi/atmel: add support for runtime PM

[Kevin Hilman]

Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> writes:

> On Fri, Oct 17, 2014 at 06:02:35AM -0700, Kevin Hilman wrote:
>> Wenyou Yang <wenyou.yang-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org> writes:
>
>> > +	if (!pm_runtime_suspended(dev)) {
>> > +		clk_disable_unprepare(as->clk);
>> > +		pinctrl_pm_select_sleep_state(dev);
>> > +	}
>
>> a.k.a. pm_runtime_put_sync() since the ->runtime_suspend() callback does
>> the same thing.
>
> Will that do the right thing when runtime PM is disabled in Kconfig?

Good point.

Then the way to make this cleaner, and obvious on inspection that system
suspend/resume are doing the same thing as runtime suspend/resume is to
have ->suspend call the runtime_suspend function.

The runtime suspend/resume functions then should be wrapped in CONFIG_PM
instead of CONFIG_PM_RUNTIME.

Kevin
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Re: [PATCH] spi/atmel: add support for runtime PM

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 1021 bytes --]

On Fri, Oct 17, 2014 at 07:22:09AM -0700, Kevin Hilman wrote:
> Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> writes:
> > On Fri, Oct 17, 2014 at 06:02:35AM -0700, Kevin Hilman wrote:
> >> Wenyou Yang <wenyou.yang-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org> writes:

> >> > +	if (!pm_runtime_suspended(dev)) {
> >> > +		clk_disable_unprepare(as->clk);
> >> > +		pinctrl_pm_select_sleep_state(dev);
> >> > +	}

> >> a.k.a. pm_runtime_put_sync() since the ->runtime_suspend() callback does
> >> the same thing.

> > Will that do the right thing when runtime PM is disabled in Kconfig?

> Good point.

> Then the way to make this cleaner, and obvious on inspection that system
> suspend/resume are doing the same thing as runtime suspend/resume is to
> have ->suspend call the runtime_suspend function.

> The runtime suspend/resume functions then should be wrapped in CONFIG_PM
> instead of CONFIG_PM_RUNTIME.

That sounds reasonable, yes.  I keep on wishing we didn't have so much
configurability in the PM :/

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RE: [PATCH] spi/atmel: add support for runtime PM

[Yang, Wenyou]

> -----Original Message-----
> From: Kevin Hilman [mailto:khilman-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org]
> Sent: Friday, October 17, 2014 10:22 PM
> To: Mark Brown
> Cc: Yang, Wenyou; linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Ferre,
> Nicolas; linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
> Subject: Re: [PATCH] spi/atmel: add support for runtime PM
> 
> Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> writes:
> 
> > On Fri, Oct 17, 2014 at 06:02:35AM -0700, Kevin Hilman wrote:
> >> Wenyou Yang <wenyou.yang-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org> writes:
> >
> >> > +	if (!pm_runtime_suspended(dev)) {
> >> > +		clk_disable_unprepare(as->clk);
> >> > +		pinctrl_pm_select_sleep_state(dev);
> >> > +	}
> >
> >> a.k.a. pm_runtime_put_sync() since the ->runtime_suspend() callback
> >> does the same thing.
> >
> > Will that do the right thing when runtime PM is disabled in Kconfig?
> 
> Good point.
> 
> Then the way to make this cleaner, and obvious on inspection that system
> suspend/resume are doing the same thing as runtime suspend/resume is to have -
> >suspend call the runtime_suspend function.
> 
> The runtime suspend/resume functions then should be wrapped in CONFIG_PM
> instead of CONFIG_PM_RUNTIME.
But if the runtime PM is disabled,  __pm_runtime_idle() return -ENOSYS, which invoked by pm_runtime_put_sync(), in spite of the runtime suspend/resume functions wrapper,

> 
> Kevin

Best Regards,
Wenyou Yang
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Re: [PATCH] spi/atmel: add support for runtime PM

[Kevin Hilman]

"Yang, Wenyou" <Wenyou.Yang-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org> writes:

>> -----Original Message-----
>> From: Kevin Hilman [mailto:khilman-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org]
>> Sent: Friday, October 17, 2014 10:22 PM
>> To: Mark Brown
>> Cc: Yang, Wenyou; linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Ferre,
>> Nicolas; linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
>> Subject: Re: [PATCH] spi/atmel: add support for runtime PM
>> 
>> Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> writes:
>> 
>> > On Fri, Oct 17, 2014 at 06:02:35AM -0700, Kevin Hilman wrote:
>> >> Wenyou Yang <wenyou.yang-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org> writes:
>> >
>> >> > +	if (!pm_runtime_suspended(dev)) {
>> >> > +		clk_disable_unprepare(as->clk);
>> >> > +		pinctrl_pm_select_sleep_state(dev);
>> >> > +	}
>> >
>> >> a.k.a. pm_runtime_put_sync() since the ->runtime_suspend() callback
>> >> does the same thing.
>> >
>> > Will that do the right thing when runtime PM is disabled in Kconfig?
>> 
>> Good point.
>> 
>> Then the way to make this cleaner, and obvious on inspection that system
>> suspend/resume are doing the same thing as runtime suspend/resume is to have -
>> >suspend call the runtime_suspend function.
>> 
>> The runtime suspend/resume functions then should be wrapped in CONFIG_PM
>> instead of CONFIG_PM_RUNTIME.
> But if the runtime PM is disabled, __pm_runtime_idle() return -ENOSYS,
> which invoked by pm_runtime_put_sync(), in spite of the runtime
> suspend/resume functions wrapper,

You won't be calling _put_sync(), instead you'll just directly call
atmel_spi_runtime_suspend().

The goal is to make it obvious upon reading that ->suspend and
->runtime_suspend are doing exactly the same thing.

Kevin

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RE: [PATCH] spi/atmel: add support for runtime PM

[Yang, Wenyou]

Hi Kevin,

> -----Original Message-----
> From: Kevin Hilman [mailto:khilman@kernel.org]
> Sent: Tuesday, October 21, 2014 2:09 AM
> To: Yang, Wenyou
> Cc: Mark Brown; linux-spi@vger.kernel.org; linux-kernel@vger.kernel.org; Ferre,
> Nicolas; linux-arm-kernel@lists.infradead.org
> Subject: Re: [PATCH] spi/atmel: add support for runtime PM
> 
> "Yang, Wenyou" <Wenyou.Yang@atmel.com> writes:
> 
> >> -----Original Message-----
> >> From: Kevin Hilman [mailto:khilman@kernel.org]
> >> Sent: Friday, October 17, 2014 10:22 PM
> >> To: Mark Brown
> >> Cc: Yang, Wenyou; linux-spi@vger.kernel.org;
> >> linux-kernel@vger.kernel.org; Ferre, Nicolas;
> >> linux-arm-kernel@lists.infradead.org
> >> Subject: Re: [PATCH] spi/atmel: add support for runtime PM
> >>
> >> Mark Brown <broonie@kernel.org> writes:
> >>
> >> > On Fri, Oct 17, 2014 at 06:02:35AM -0700, Kevin Hilman wrote:
> >> >> Wenyou Yang <wenyou.yang@atmel.com> writes:
> >> >
> >> >> > +	if (!pm_runtime_suspended(dev)) {
> >> >> > +		clk_disable_unprepare(as->clk);
> >> >> > +		pinctrl_pm_select_sleep_state(dev);
> >> >> > +	}
> >> >
> >> >> a.k.a. pm_runtime_put_sync() since the ->runtime_suspend()
> >> >> callback does the same thing.
> >> >
> >> > Will that do the right thing when runtime PM is disabled in Kconfig?
> >>
> >> Good point.
> >>
> >> Then the way to make this cleaner, and obvious on inspection that
> >> system suspend/resume are doing the same thing as runtime
> >> suspend/resume is to have -
> >> >suspend call the runtime_suspend function.
> >>
> >> The runtime suspend/resume functions then should be wrapped in
> >> CONFIG_PM instead of CONFIG_PM_RUNTIME.
> > But if the runtime PM is disabled, __pm_runtime_idle() return -ENOSYS,
> > which invoked by pm_runtime_put_sync(), in spite of the runtime
> > suspend/resume functions wrapper,
> 
> You won't be calling _put_sync(), instead you'll just directly call
> atmel_spi_runtime_suspend().
Got it , I will change it. Thanks.

> 
> The goal is to make it obvious upon reading that ->suspend and
> ->runtime_suspend are doing exactly the same thing.
> 
> Kevin

Best Regards,
Wenyou Yang

RE: [PATCH] spi/atmel: add support for runtime PM

[Yang, Wenyou]

> -----Original Message-----
> From: Kevin Hilman [mailto:khilman-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org]
> Sent: Friday, October 17, 2014 9:03 PM
> To: Yang, Wenyou
> Cc: broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org; linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org;
> Ferre, Nicolas; linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
> Subject: Re: [PATCH] spi/atmel: add support for runtime PM
> 
> Wenyou Yang <wenyou.yang-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org> writes:
> 
> > Drivers should put the device into low power states proactively
> > whenever the device is not in use. Thus implement support for runtime
> > PM and use the autosuspend feature to make sure that we can still
> > perform well in case we see lots of SPI traffic within short period of time.
> >
> > Signed-off-by: Wenyou Yang <wenyou.yang-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
> > ---
> >  drivers/spi/spi-atmel.c |   62
> +++++++++++++++++++++++++++++++++++++++++------
> >  1 file changed, 55 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c index
> > 649dcb5..aca285e 100644
> > --- a/drivers/spi/spi-atmel.c
> > +++ b/drivers/spi/spi-atmel.c
> > @@ -26,6 +26,7 @@
> >  #include <linux/io.h>
> >  #include <linux/gpio.h>
> >  #include <linux/pinctrl/consumer.h>
> > +#include <linux/pm_runtime.h>
> >
> >  /* SPI register offsets */
> >  #define SPI_CR					0x0000
> > @@ -191,6 +192,8 @@
> >
> >  #define SPI_DMA_TIMEOUT		(msecs_to_jiffies(1000))
> >
> > +#define AUTOSUSPEND_TIMEOUT	2000
> > +
> >  struct atmel_spi_dma {
> >  	struct dma_chan			*chan_rx;
> >  	struct dma_chan			*chan_tx;
> > @@ -1313,6 +1316,7 @@ static int atmel_spi_probe(struct platform_device
> *pdev)
> >  	master->setup = atmel_spi_setup;
> >  	master->transfer_one_message = atmel_spi_transfer_one_message;
> >  	master->cleanup = atmel_spi_cleanup;
> > +	master->auto_runtime_pm = true;
> >  	platform_set_drvdata(pdev, master);
> >
> >  	as = spi_master_get_devdata(master); @@ -1385,6 +1389,11 @@ static
> > int atmel_spi_probe(struct platform_device *pdev)
> >  	dev_info(&pdev->dev, "Atmel SPI Controller at 0x%08lx (irq %d)\n",
> >  			(unsigned long)regs->start, irq);
> >
> > +	pm_runtime_set_autosuspend_delay(&pdev->dev,
> AUTOSUSPEND_TIMEOUT);
> > +	pm_runtime_use_autosuspend(&pdev->dev);
> > +	pm_runtime_set_active(&pdev->dev);
> > +	pm_runtime_enable(&pdev->dev);
> > +
> >  	ret = devm_spi_register_master(&pdev->dev, master);
> >  	if (ret)
> >  		goto out_free_dma;
> > @@ -1392,6 +1401,9 @@ static int atmel_spi_probe(struct platform_device
> *pdev)
> >  	return 0;
> >
> >  out_free_dma:
> > +	pm_runtime_disable(&pdev->dev);
> > +	pm_runtime_set_suspended(&pdev->dev);
> > +
> >  	if (as->use_dma)
> >  		atmel_spi_release_dma(as);
> >
> > @@ -1413,6 +1425,8 @@ static int atmel_spi_remove(struct platform_device
> *pdev)
> >  	struct spi_master	*master = platform_get_drvdata(pdev);
> >  	struct atmel_spi	*as = spi_master_get_devdata(master);
> >
> > +	pm_runtime_get_sync(&pdev->dev);
> > +
> >  	/* reset the hardware and block queue progress */
> >  	spin_lock_irq(&as->lock);
> >  	if (as->use_dma) {
> > @@ -1430,9 +1444,13 @@ static int atmel_spi_remove(struct
> > platform_device *pdev)
> >
> >  	clk_disable_unprepare(as->clk);
> >
> > +	pm_runtime_put_noidle(&pdev->dev);
> 
> Why the _noidle version?
 Because invoked from the _remove function, only decrement the device's usage counter, no further idle operation need.

> 
> > +	pm_runtime_disable(&pdev->dev);
> > +
> >  	return 0;
> >  }
> >
> > +#ifdef CONFIG_PM
> 
> Why CONFIG_PM?  CONFIG_PM_SLEEP  causes CONFIG_PM=y, so this seems
> redundant.
Accepted, I will remove it.

> 
> >  #ifdef CONFIG_PM_SLEEP
> >  static int atmel_spi_suspend(struct device *dev)  { @@ -1447,9
> > +1465,10 @@ static int atmel_spi_suspend(struct device *dev)
> >  		return ret;
> >  	}
> >
> > -	clk_disable_unprepare(as->clk);
> > -
> > -	pinctrl_pm_select_sleep_state(dev);
> > +	if (!pm_runtime_suspended(dev)) {
> > +		clk_disable_unprepare(as->clk);
> > +		pinctrl_pm_select_sleep_state(dev);
> > +	}
> 
> a.k.a. pm_runtime_put_sync() since the ->runtime_suspend() callback does the
> same thing.
> 
> >  	return 0;
> >  }
> > @@ -1460,9 +1479,10 @@ static int atmel_spi_resume(struct device *dev)
> >  	struct atmel_spi	*as = spi_master_get_devdata(master);
> >  	int ret;
> >
> > -	pinctrl_pm_select_default_state(dev);
> > -
> > -	clk_prepare_enable(as->clk);
> > +	if (!pm_runtime_suspended(dev)) {
> > +		pinctrl_pm_select_default_state(dev);
> > +		clk_prepare_enable(as->clk);
> > +	}
> 
> a.k.a. pm_runtime_get_sync()
> 
> Kevin
> 
> >  	/* Start the queue running */
> >  	ret = spi_master_resume(master);
> > @@ -1471,9 +1491,37 @@ static int atmel_spi_resume(struct device *dev)
> >
> >  	return ret;
> >  }
> > +#endif
> >
> > -static SIMPLE_DEV_PM_OPS(atmel_spi_pm_ops, atmel_spi_suspend,
> > atmel_spi_resume);
> > +#ifdef CONFIG_PM_RUNTIME
> > +static int atmel_spi_runtime_suspend(struct device *dev) {
> > +	struct spi_master *master = dev_get_drvdata(dev);
> > +	struct atmel_spi *as = spi_master_get_devdata(master);
> >
> > +	clk_disable_unprepare(as->clk);
> > +	pinctrl_pm_select_sleep_state(dev);
> > +
> > +	return 0;
> > +}
> > +
> > +static int atmel_spi_runtime_resume(struct device *dev) {
> > +	struct spi_master *master = dev_get_drvdata(dev);
> > +	struct atmel_spi *as = spi_master_get_devdata(master);
> > +
> > +	pinctrl_pm_select_default_state(dev);
> > +	clk_prepare_enable(as->clk);
> > +
> > +	return 0;
> > +}
> > +#endif
> > +
> > +static const struct dev_pm_ops atmel_spi_pm_ops = {
> > +	SET_SYSTEM_SLEEP_PM_OPS(atmel_spi_suspend, atmel_spi_resume)
> > +	SET_RUNTIME_PM_OPS(atmel_spi_runtime_suspend,
> > +			   atmel_spi_runtime_resume, NULL) };
> >  #define ATMEL_SPI_PM_OPS	(&atmel_spi_pm_ops)
> >  #else
> >  #define ATMEL_SPI_PM_OPS	NULL

Best Regards,
Wenyou Yang
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