RE: [Patch V9] i2c: imx: add runtime pm support to improve the performance

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> -----Original Message-----
> From: Gao Pan-B54642
> Sent: Wednesday, November 04, 2015 9:29 AM
> To: 'Gao Pan'; wsa@xxxxxxxxxxxxx
> Cc: linux-i2c@xxxxxxxxxxxxxxx; Li Frank-B20596; Duan Fugang-B38611; u.kleine-
> koenig@xxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx; hkallweit1@xxxxxxxxx;
> s.hauer@xxxxxxxxxxxxxx
> Subject: RE: [Patch V9] i2c: imx: add runtime pm support to improve the
> performance
> 
> Ping...
> 
> > -----Original Message-----
> > From: Gao Pan [mailto:b54642@xxxxxxxxxxxxx]
> > Sent: Monday, October 26, 2015 2:55 PM
> > To: wsa@xxxxxxxxxxxxx
> > Cc: linux-i2c@xxxxxxxxxxxxxxx; Li Frank-B20596; Duan Fugang-B38611;
> > Gao Pan- B54642; u.kleine-koenig@xxxxxxxxxxxxxx;
> > kernel@xxxxxxxxxxxxxx; hkallweit1@xxxxxxxxx; s.hauer@xxxxxxxxxxxxxx
> > Subject: [Patch V9] i2c: imx: add runtime pm support to improve the
> > performance
> >
> > In our former i2c driver, i2c clk is enabled and disabled in xfer
> > function, which contributes to power saving. However, the clk enable
> > process brings a busy wait delay until the core is stable. As a result, the
> performance is sacrificed.
> >
> > To weigh the power consumption and i2c bus performance, runtime pm is
> > the good solution for it. The clk is enabled when a i2c transfer
> > starts, and disabled after a specifically defined delay.
> >
> > If CONFIG_PM is disabled the net result of this patch is that the
> > clock is never disabled.
> >
> > Without the patch the test case (many eeprom reads) executes with approx:
> > real 1m7.735s
> > user 0m0.488s
> > sys 0m20.040s
> >
> > With the patch the same test case (many eeprom reads) executes with approx:
> > real 0m54.241s
> > user 0m0.440s
> > sys 0m5.920s
> >
> > Signed-off-by: Fugang Duan <B38611@xxxxxxxxxxxxx>
> > Signed-off-by: Gao Pan <b54642@xxxxxxxxxxxxx>
> > ---
> > V2:
> > As Uwe Kleine-König's suggestion, the version do below changes:
> >  -call clk_prepare_enable in probe to avoid never enabling clock
> >   if CONFIG_PM is disabled
> >  -enable clock before request IRQ in probe  -remove the pm staff in
> > i2c_imx_isr
> >
> > V3:
> >  -pm_runtime_get_sync returns < 0 as error
> >
> > V4:
> >  -add pm_runtime_set_active before pm_runtime_enable  -replace
> > pm_runtime_put_autosuspend with pm_runtime_autosuspend
> >   in probe
> >  -add error disposal when i2c_add_numbered_adapter fails
> >
> > V5:
> >  -clean up and disable runtime PM when i2c_add_numbered_adapter fails
> > -use pm_runtime_get and pm_runtime_put_autosuspend in probe
> >
> > V6:
> >  -disable the clock manually and set the state to suspended explicitly with
> >   pm_runtime_set_suspended
> >
> > V7:
> >  -manually disabling the clock and use pm_runtime_put_noidle in the
> > remove callback
> >
> > V8:
> >  -move out label after the two runtime pm calls in i2c_imx_xfer
> >
> > V9:
> >  -add comment in the log what is the result when CONFIG_PM is disabled
> > -do the rpm_disable cleanup in reverse order
> >
> >  drivers/i2c/busses/i2c-imx.c | 90
> > ++++++++++++++++++++++++++++++++++++++------
> >  1 file changed, 78 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-imx.c
> > b/drivers/i2c/busses/i2c-imx.c index 8d46e74..d2a379f 100644
> > --- a/drivers/i2c/busses/i2c-imx.c
> > +++ b/drivers/i2c/busses/i2c-imx.c
> > @@ -54,6 +54,7 @@
> >  #include <linux/platform_device.h>
> >  #include <linux/sched.h>
> >  #include <linux/slab.h>
> > +#include <linux/pm_runtime.h>
> >
> >  /** Defines
> > ********************************************************************
> >
> > **********************************************************************
> > *********/
> > @@ -119,6 +120,8 @@
> >  #define I2CR_IEN_OPCODE_0	0x0
> >  #define I2CR_IEN_OPCODE_1	I2CR_IEN
> >
> > +#define I2C_PM_TIMEOUT		10 /* ms */
> > +
> >  /** Variables
> > ******************************************************************
> >
> > **********************************************************************
> > *********/
> >
> > @@ -526,9 +529,6 @@ static int i2c_imx_start(struct imx_i2c_struct
> > *i2c_imx)
> >
> >  	i2c_imx_set_clk(i2c_imx);
> >
> > -	result = clk_prepare_enable(i2c_imx->clk);
> > -	if (result)
> > -		return result;
> >  	imx_i2c_write_reg(i2c_imx->ifdr, i2c_imx, IMX_I2C_IFDR);
> >  	/* Enable I2C controller */
> >  	imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx,
> > IMX_I2C_I2SR); @@ -581,7 +581,6 @@ static void i2c_imx_stop(struct
> imx_i2c_struct *i2c_imx)
> >  	/* Disable I2C controller */
> >  	temp = i2c_imx->hwdata->i2cr_ien_opcode ^ I2CR_IEN,
> >  	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
> > -	clk_disable_unprepare(i2c_imx->clk);
> >  }
> >
> >  static irqreturn_t i2c_imx_isr(int irq, void *dev_id) @@ -900,6
> > +899,10 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
> >
> >  	dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
> >
> > +	result = pm_runtime_get_sync(i2c_imx->adapter.dev.parent);
> > +	if (result < 0)
> > +		goto out;
> > +
> >  	/* Start I2C transfer */
> >  	result = i2c_imx_start(i2c_imx);
> >  	if (result) {
> > @@ -963,6 +966,10 @@ fail0:
> >  	/* Stop I2C transfer */
> >  	i2c_imx_stop(i2c_imx);
> >
> > +	pm_runtime_mark_last_busy(i2c_imx->adapter.dev.parent);
> > +	pm_runtime_put_autosuspend(i2c_imx->adapter.dev.parent);
> > +
> > +out:
> >  	dev_dbg(&i2c_imx->adapter.dev, "<%s> exit with: %s: %d\n", __func__,
> >  		(result < 0) ? "error" : "success msg",
> >  			(result < 0) ? result : num);
> > @@ -1082,7 +1089,7 @@ static int i2c_imx_probe(struct platform_device
> > *pdev)
> >
> >  	ret = clk_prepare_enable(i2c_imx->clk);
> >  	if (ret) {
> > -		dev_err(&pdev->dev, "can't enable I2C clock\n");
> > +		dev_err(&pdev->dev, "can't enable I2C clock, ret=%d\n", ret);
> >  		return ret;
> >  	}
> >
> > @@ -1106,6 +1113,18 @@ static int i2c_imx_probe(struct platform_device *pdev)
> >  	/* Set up adapter data */
> >  	i2c_set_adapdata(&i2c_imx->adapter, i2c_imx);
> >
> > +	/* Set up platform driver data */
> > +	platform_set_drvdata(pdev, i2c_imx);
> > +
> > +	pm_runtime_set_autosuspend_delay(&pdev->dev, I2C_PM_TIMEOUT);
> > +	pm_runtime_use_autosuspend(&pdev->dev);
> > +	pm_runtime_set_active(&pdev->dev);
> > +	pm_runtime_enable(&pdev->dev);
> > +
> > +	ret = pm_runtime_get_sync(&pdev->dev);
> > +	if (ret < 0)
> > +		goto rpm_disable;
> > +
> >  	/* Set up clock divider */
> >  	i2c_imx->bitrate = IMX_I2C_BIT_RATE;
> >  	ret = of_property_read_u32(pdev->dev.of_node,
> > @@ -1122,14 +1141,13 @@ static int i2c_imx_probe(struct platform_device *pdev)
> >  	ret = i2c_add_numbered_adapter(&i2c_imx->adapter);
> >  	if (ret < 0) {
> >  		dev_err(&pdev->dev, "registration failed\n");
> > -		goto clk_disable;
> > +		goto rpm_disable;
> >  	}
> >
> >  	i2c_imx_init_recovery_info(i2c_imx, pdev);
> >
> > -	/* Set up platform driver data */
> > -	platform_set_drvdata(pdev, i2c_imx);
> > -	clk_disable_unprepare(i2c_imx->clk);
> > +	pm_runtime_mark_last_busy(&pdev->dev);
> > +	pm_runtime_put_autosuspend(&pdev->dev);
> >
> >  	dev_dbg(&i2c_imx->adapter.dev, "claimed irq %d\n", irq);
> >  	dev_dbg(&i2c_imx->adapter.dev, "device resources: %pR\n", res); @@
> > -1142,6
> > +1160,12 @@ static int i2c_imx_probe(struct platform_device *pdev)
> >
> >  	return 0;   /* Return OK */
> >
> > +rpm_disable:
> > +	pm_runtime_put_noidle(&pdev->dev);
> > +	pm_runtime_disable(&pdev->dev);
> > +	pm_runtime_set_suspended(&pdev->dev);
> > +	pm_runtime_dont_use_autosuspend(&pdev->dev);
> > +
> >  clk_disable:
> >  	clk_disable_unprepare(i2c_imx->clk);
> >  	return ret;
> > @@ -1150,6 +1174,11 @@ clk_disable:
> >  static int i2c_imx_remove(struct platform_device *pdev)  {
> >  	struct imx_i2c_struct *i2c_imx = platform_get_drvdata(pdev);
> > +	int ret;
> > +
> > +	ret = pm_runtime_get_sync(&pdev->dev);
> > +	if (ret < 0)
> > +		return ret;
> >
> >  	/* remove adapter */
> >  	dev_dbg(&i2c_imx->adapter.dev, "adapter removed\n"); @@ -1164,17
> > +1193,54 @@ static int i2c_imx_remove(struct platform_device *pdev)
> >  	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2CR);
> >  	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2SR);
> >
> > +	clk_disable_unprepare(i2c_imx->clk);
> > +
> > +	pm_runtime_put_noidle(&pdev->dev);
> > +	pm_runtime_disable(&pdev->dev);
> > +
> > +	return 0;
> > +}
> > +
> > +#ifdef CONFIG_PM
> > +static int i2c_imx_runtime_suspend(struct device *dev) {
> > +	struct imx_i2c_struct *i2c_imx  = dev_get_drvdata(dev);
> > +
> > +	clk_disable_unprepare(i2c_imx->clk);
> > +
> >  	return 0;
> >  }
> >
> > +static int i2c_imx_runtime_resume(struct device *dev) {
> > +	struct imx_i2c_struct *i2c_imx  = dev_get_drvdata(dev);
> > +	int ret;
> > +
> > +	ret = clk_prepare_enable(i2c_imx->clk);
> > +	if (ret)
> > +		dev_err(dev, "can't enable I2C clock, ret=%d\n", ret);
> > +
> > +	return ret;
> > +}
> > +
> > +static const struct dev_pm_ops i2c_imx_pm_ops = {
> > +	SET_RUNTIME_PM_OPS(i2c_imx_runtime_suspend,
> > +			   i2c_imx_runtime_resume, NULL)
> > +};
> > +#define I2C_IMX_PM_OPS (&i2c_imx_pm_ops) #else #define I2C_IMX_PM_OPS
> > +NULL #endif /* CONFIG_PM */
> > +
> >  static struct platform_driver i2c_imx_driver = {
> >  	.probe = i2c_imx_probe,
> >  	.remove = i2c_imx_remove,
> > -	.driver	= {
> > -		.name	= DRIVER_NAME,
> > +	.driver = {
> > +		.name = DRIVER_NAME,
> > +		.pm = I2C_IMX_PM_OPS,
> >  		.of_match_table = i2c_imx_dt_ids,
> >  	},
> > -	.id_table	= imx_i2c_devtype,
> > +	.id_table = imx_i2c_devtype,
> >  };
> >
> >  static int __init i2c_adap_imx_init(void)
> > --
> > 1.9.1

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