From: Heiner Kallweit <mailto:hkallweit1@xxxxxxxxx> Sent: Friday, August 28, 2015 1:50 PM > To: Gao Pan-B54642; wsa@xxxxxxxxxxxxx > Cc: linux-i2c@xxxxxxxxxxxxxxx; Li Frank-B20596; Duan Fugang-B38611; > u.kleine-koenig@xxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx > Subject: Re: [Patch V5] i2c: imx: add runtime pm support to improve the > performance > > Am 27.08.2015 um 09:06 schrieb Gao Pandy: > > From: Heiner Kallweit <mailto:hkallweit1@xxxxxxxxx> Sent: Thursday, > > August 27, 2015 1:50 PM > >> To: Gao Pan-B54642; wsa@xxxxxxxxxxxxx > >> Cc: linux-i2c@xxxxxxxxxxxxxxx; Li Frank-B20596; Duan Fugang-B38611; > >> u.kleine-koenig@xxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx > >> Subject: Re: [Patch V5] i2c: imx: add runtime pm support to improve > >> the performance > >> > >> Am 27.08.2015 um 06:01 schrieb Gao Pandy: > >>> From: Heiner Kallweit <mailto:hkallweit1@xxxxxxxxx> Sent: Thursday, > >>> August 27, 2015 2:52 AM > >>>> To: Gao Pan-B54642; wsa@xxxxxxxxxxxxx > >>>> Cc: linux-i2c@xxxxxxxxxxxxxxx; Li Frank-B20596; Duan Fugang-B38611; > >>>> u.kleine-koenig@xxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx > >>>> Subject: Re: [Patch V5] i2c: imx: add runtime pm support to improve > >>>> the performance > >>>> > >>>> Am 26.08.2015 um 07:23 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. > >>>>> > >>>>> 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. > >>>>> > >>>>> 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> > >>>>> [wsa: fixed some indentation] > >>>>> Signed-off-by: Wolfram Sang <wsa@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 > >>>>> > >>>>> drivers/i2c/busses/i2c-imx.c | 91 > >>>>> ++++++++++++++++++++++++++++++++++++-------- > >>>>> 1 file changed, 76 insertions(+), 15 deletions(-) > >>>>> > >>>>> diff --git a/drivers/i2c/busses/i2c-imx.c > >>>>> b/drivers/i2c/busses/i2c-imx.c index 785aa67..8940a89 100644 > >>>>> --- a/drivers/i2c/busses/i2c-imx.c > >>>>> +++ b/drivers/i2c/busses/i2c-imx.c > >>>>> @@ -53,6 +53,7 @@ > >>>>> #include <linux/platform_device.h> #include <linux/sched.h> > >>>>> #include <linux/slab.h> > >>>>> +#include <linux/pm_runtime.h> > >>>>> > >>>>> /** Defines > >>>>> ****************************************************************** > >>>>> ** > >>>>> > >>>>> ****************************************************************** > >>>>> ** > >>>>> ** > >>>>> *********/ > >>>>> @@ -118,6 +119,8 @@ > >>>>> #define I2CR_IEN_OPCODE_0 0x0 > >>>>> #define I2CR_IEN_OPCODE_1 I2CR_IEN > >>>>> > >>>>> +#define I2C_PM_TIMEOUT 10 /* ms */ > >>>>> + > >>>>> /** Variables > >>>>> ****************************************************************** > >>>>> > >>>>> ****************************************************************** > >>>>> ** > >>>>> ** > >>>>> *********/ > >>>>> > >>>>> @@ -520,9 +523,6 @@ 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); @@ -575,7 +575,6 @@ 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) @@ -894,6 > >>>>> +893,10 @@ 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) > >>>>> @@ -950,6 +953,10 @@ fail0: > >>>>> /* Stop I2C transfer */ > >>>>> i2c_imx_stop(i2c_imx); > >>>>> > >>>>> +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); > >>>>> @@ -1020,15 +1027,17 @@ 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; > >>>>> } > >>>>> + > >>>>> /* Request IRQ */ > >>>>> ret = devm_request_irq(&pdev->dev, irq, i2c_imx_isr, 0, > >>>>> pdev->name, i2c_imx); > >>>>> if (ret) { > >>>>> dev_err(&pdev->dev, "can't claim irq %d\n", irq); > >>>>> - goto clk_disable; > >>>>> + clk_disable_unprepare(i2c_imx->clk); > >>>>> + return ret; > >>>>> } > >>>>> > >>>>> /* Init queue */ > >>>>> @@ -1037,6 +1046,18 @@ 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(&pdev->dev); > >>>>> + if (ret < 0) > >>>>> + return ret; > >>>>> + > >>>>> /* Set up clock divider */ > >>>>> i2c_imx->bitrate = IMX_I2C_BIT_RATE; > >>>>> ret = of_property_read_u32(pdev->dev.of_node, > >>>>> @@ -1053,12 +1074,11 @@ 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; > >>>>> } > >>>>> > >>>>> - /* 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); > >>>>> @@ > >>>>> -1071,14 +1091,20 @@ static int i2c_imx_probe(struct > >>>>> platform_device > >>>>> *pdev) > >>>>> > >>>>> return 0; /* Return OK */ > >>>>> > >>>>> -clk_disable: > >>>>> - clk_disable_unprepare(i2c_imx->clk); > >>>>> +rpm_disable: > >>>>> + pm_runtime_put(&pdev->dev); > >>>>> + pm_runtime_disable(&pdev->dev); > >>>> The cleanup has to be in reverse order of the setup. Therefore the > >>>> rpm cleanup should happen before the clock disabling. > >>>> As it is now you wouldn't disable the clock when registration fails. > >>> > >>> Thanks. When registration fails, pm_runtime_put is used to cleanup > >>> the > >> runtime status and disable clk. > >>> Actually, I think pm_runtime_put_sync_suspend is better here. > >> You have another error path where only the clock has to be disabled > >> (getting irq fails) as rpm isn't set up yet. Therefore you can't > >> combine both cleanups. > >> And even despite the fact that suspending and disabling clock > >> technically is the same using suspend in an error path is not > >> intuitive (as there's no way to resume). > >> > >>> > >>> > >>>> And better use pm_runtime_put_noidle. You don't want to suspend > >>>> here if the ref count is 0. > >>>> > >>>> Last but not least a call to pm_runtime_set_suspended is missing > >>>> (because after disabling the clock the device effectively is in > >> suspended state). > >>> > >>> The status is set suspended in pm_runtime_put_sync_suspend, so > >> pm_runtime_set_suspended is unnecessary here. > >>> What do you think about it? > >>> > >>> Please see the following code: > >>> rpm_disable: > >>> pm_runtime_put_sync_suspend(&pdev->dev); > >>> pm_runtime_disable(&pdev->dev); > >>> return ret; > >>> > >> See above. Better disable the clock manually and set the state to > >> suspended explicitly. > >> > >>>>> return ret; > >>>>> > > > > Thanks a lot! How about the following logic? > > > > /* Request IRQ */ > > ret = devm_request_irq(&pdev->dev, irq, i2c_imx_isr, 0, > > pdev->name, i2c_imx); > > if (ret) { > > dev_err(&pdev->dev, "can't claim irq %d\n", irq); > > goto clk_disable; > > } > > > > ret = pm_runtime_get(&pdev->dev); > > if (ret < 0) > > goto rpm_disable; > > > > 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; > > > To be on the very safe side you could use pm_runtime_get_sync instead of > pm_runtime_get. > Apart from that it looks ok to me now. Thanks, I will send V6 immediately and hope get your ack. > >>>>> > >>>>> 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"); @@ - > 1093,17 > >>>>> +1119,52 @@ 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); > >>>>> > >>>>> + pm_runtime_put_sync(&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) > >>>>> > >>> > > ��.n��������+%������w��{.n�����{��-��)�� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
