From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiner Kallweit Subject: Re: [Patch V7] i2c: imx: add runtime pm support to improve the performance Date: Tue, 01 Sep 2015 08:06:26 +0200 Message-ID: <55E54062.8030909@gmail.com> References: <1441006353-874-1-git-send-email-b54642@freescale.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1441006353-874-1-git-send-email-b54642-KZfg59tc24xl57MIdRCFDg@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Gao Pan , wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, B20596-KZfg59tc24xl57MIdRCFDg@public.gmane.org, b38611-KZfg59tc24xl57MIdRCFDg@public.gmane.org, u.kleine-koenig-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org, kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org List-Id: linux-i2c@vger.kernel.org Am 31.08.2015 um 09:32 schrieb Gao Pan: > 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. >=20 > 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. >=20 > Without the patch the test case (many eeprom reads) executes with app= rox: > real 1m7.735s > user 0m0.488s > sys 0m20.040s >=20 > With the patch the same test case (many eeprom reads) executes with a= pprox: > real 0m54.241s > user 0m0.440s > sys 0m5.920s >=20 > Signed-off-by: Fugang Duan > Signed-off-by: Gao Pan > [wsa: fixed some indentation] > Signed-off-by: Wolfram Sang > --- > V2: > As Uwe Kleine-K=C3=B6nig'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 >=20 > V3: > -pm_runtime_get_sync returns < 0 as error >=20 > 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 >=20 > V5: > -clean up and disable runtime PM when i2c_add_numbered_adapter fails > -use pm_runtime_get and pm_runtime_put_autosuspend in probe >=20 > V6: > -disable the clock manually and set the state to suspended explicitl= y with > pm_runtime_set_suspended >=20 > V7: > -manually disabling the clock and use pm_runtime_put_noidle in the r= emove callback >=20 > drivers/i2c/busses/i2c-imx.c | 90 ++++++++++++++++++++++++++++++++++= ++++------ > 1 file changed, 78 insertions(+), 12 deletions(-) >=20 > diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-im= x.c > index 785aa67..d7c823b 100644 > --- a/drivers/i2c/busses/i2c-imx.c > +++ b/drivers/i2c/busses/i2c-imx.c > @@ -53,6 +53,7 @@ > #include > #include > #include > +#include > =20 > /** Defines ********************************************************= ************ > ********************************************************************= ***********/ > @@ -118,6 +119,8 @@ > #define I2CR_IEN_OPCODE_0 0x0 > #define I2CR_IEN_OPCODE_1 I2CR_IEN > =20 > +#define I2C_PM_TIMEOUT 10 /* ms */ > + > /** Variables ******************************************************= ************ > ********************************************************************= ***********/ > =20 > @@ -520,9 +523,6 @@ static int i2c_imx_start(struct imx_i2c_struct *i= 2c_imx) > =20 > i2c_imx_set_clk(i2c_imx); > =20 > - result =3D 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_I2= C_I2SR); > @@ -575,7 +575,6 @@ static void i2c_imx_stop(struct imx_i2c_struct *i= 2c_imx) > /* Disable I2C controller */ > temp =3D i2c_imx->hwdata->i2cr_ien_opcode ^ I2CR_IEN, > imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); > - clk_disable_unprepare(i2c_imx->clk); > } > =20 > static irqreturn_t i2c_imx_isr(int irq, void *dev_id) > @@ -894,6 +893,10 @@ static int i2c_imx_xfer(struct i2c_adapter *adap= ter, > =20 > dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); > =20 > + result =3D pm_runtime_get_sync(i2c_imx->adapter.dev.parent); > + if (result < 0) > + goto out; > + > /* Start I2C transfer */ > result =3D i2c_imx_start(i2c_imx); > if (result) > @@ -950,6 +953,10 @@ fail0: > /* Stop I2C transfer */ > i2c_imx_stop(i2c_imx); > =20 > +out: > + pm_runtime_mark_last_busy(i2c_imx->adapter.dev.parent); > + pm_runtime_put_autosuspend(i2c_imx->adapter.dev.parent); > + > dev_dbg(&i2c_imx->adapter.dev, "<%s> exit with: %s: %d\n", __func__= , > (result < 0) ? "error" : "success msg", > (result < 0) ? result : num); > @@ -1020,9 +1027,10 @@ static int i2c_imx_probe(struct platform_devic= e *pdev) > =20 > ret =3D 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=3D%d\n", ret); > return ret; > } > + > /* Request IRQ */ > ret =3D devm_request_irq(&pdev->dev, irq, i2c_imx_isr, 0, > pdev->name, i2c_imx); > @@ -1037,6 +1045,18 @@ static int i2c_imx_probe(struct platform_devic= e *pdev) > /* Set up adapter data */ > i2c_set_adapdata(&i2c_imx->adapter, i2c_imx); > =20 > + /* 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 =3D pm_runtime_get_sync(&pdev->dev); > + if (ret < 0) > + goto rpm_disable; > + > /* Set up clock divider */ > i2c_imx->bitrate =3D IMX_I2C_BIT_RATE; > ret =3D of_property_read_u32(pdev->dev.of_node, > @@ -1053,12 +1073,11 @@ static int i2c_imx_probe(struct platform_devi= ce *pdev) > ret =3D i2c_add_numbered_adapter(&i2c_imx->adapter); > if (ret < 0) { > dev_err(&pdev->dev, "registration failed\n"); > - goto clk_disable; > + goto rpm_disable; > } > =20 > - /* 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); > =20 > dev_dbg(&i2c_imx->adapter.dev, "claimed irq %d\n", irq); > dev_dbg(&i2c_imx->adapter.dev, "device resources: %pR\n", res); > @@ -1071,6 +1090,11 @@ static int i2c_imx_probe(struct platform_devic= e *pdev) > =20 > return 0; /* Return OK */ > =20 > +rpm_disable: > + pm_runtime_put_noidle(&pdev->dev); > + pm_runtime_disable(&pdev->dev); > + pm_runtime_set_suspended(&pdev->dev); > + > clk_disable: > clk_disable_unprepare(i2c_imx->clk); > return ret; > @@ -1079,6 +1103,11 @@ clk_disable: > static int i2c_imx_remove(struct platform_device *pdev) > { > struct imx_i2c_struct *i2c_imx =3D platform_get_drvdata(pdev); > + int ret; > + > + ret =3D pm_runtime_get_sync(&pdev->dev); > + if (ret < 0) > + return ret; > =20 > /* remove adapter */ > dev_dbg(&i2c_imx->adapter.dev, "adapter removed\n"); > @@ -1093,17 +1122,54 @@ static int i2c_imx_remove(struct platform_dev= ice *pdev) > imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2CR); > imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2SR); > =20 > + 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 =3D dev_get_drvdata(dev); > + > + clk_disable_unprepare(i2c_imx->clk); > + > return 0; > } > =20 > +static int i2c_imx_runtime_resume(struct device *dev) > +{ > + struct imx_i2c_struct *i2c_imx =3D dev_get_drvdata(dev); > + int ret; > + > + ret =3D clk_prepare_enable(i2c_imx->clk); > + if (ret) > + dev_err(dev, "can't enable I2C clock, ret=3D%d\n", ret); > + > + return ret; > +} > + > +static const struct dev_pm_ops i2c_imx_pm_ops =3D { > + 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 =3D { > .probe =3D i2c_imx_probe, > .remove =3D i2c_imx_remove, > - .driver =3D { > - .name =3D DRIVER_NAME, > + .driver =3D { > + .name =3D DRIVER_NAME, > + .pm =3D I2C_IMX_PM_OPS, > .of_match_table =3D i2c_imx_dt_ids, > }, > - .id_table =3D imx_i2c_devtype, > + .id_table =3D imx_i2c_devtype, > }; > =20 > static int __init i2c_adap_imx_init(void) >=20 Looks good to me now. Regards, Heiner