Ping... > From: Gao Pan [mailto:b54642@xxxxxxxxxxxxx] > Sent: Thursday, June 11, 2015 9:50 AM > To: wsa@xxxxxxxxxxxxx > Cc: linux-i2c@xxxxxxxxxxxxxxx; Li Frank-B20596; Duan Fugang-B38611 > Subject: [Patch v1] 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 consuption and i2c bus performance, runtime pm is > the good solution for it. The clk is enabled when a i2c transfer > starts, and disabled afer 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 > > From the test result, the patch get better performance. > > Signed-off-by: Fugang Duan <B38611@xxxxxxxxxxxxx> > Signed-off-by: Gao Pan <b54642@xxxxxxxxxxxxx> > --- > drivers/i2c/busses/i2c-imx.c | 78 > +++++++++++++++++++++++++++++++++++++- > ------ > 1 file changed, 66 insertions(+), 12 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-imx.c > b/drivers/i2c/busses/i2c-imx.c index 785aa67..cc4b5d6 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) @@ -583,6 > +582,9 @@ static irqreturn_t i2c_imx_isr(int irq, void *dev_id) > struct imx_i2c_struct *i2c_imx = dev_id; > unsigned int temp; > > + if (pm_runtime_suspended(i2c_imx->adapter.dev.parent)) > + return IRQ_NONE; > + > temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR); > if (temp & I2SR_IIF) { > /* save status register */ > @@ -894,6 +896,10 @@ 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 (IS_ERR_VALUE(result)) > + goto out; > + > /* Start I2C transfer */ > result = i2c_imx_start(i2c_imx); > if (result) > @@ -950,6 +956,10 @@ 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); > @@ -1018,11 +1028,6 @@ static int i2c_imx_probe(struct platform_device > *pdev) > return PTR_ERR(i2c_imx->clk); > } > > - ret = clk_prepare_enable(i2c_imx->clk); > - if (ret) { > - dev_err(&pdev->dev, "can't enable I2C clock\n"); > - return ret; > - } > /* Request IRQ */ > ret = devm_request_irq(&pdev->dev, irq, i2c_imx_isr, 0, > pdev->name, i2c_imx); > @@ -1037,6 +1042,14 @@ 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_enable(&pdev->dev); > + pm_runtime_set_autosuspend_delay(&pdev->dev, I2C_PM_TIMEOUT); > + pm_runtime_use_autosuspend(&pdev->dev); > + pm_runtime_get_sync(&pdev->dev); > + > /* Set up clock divider */ > i2c_imx->bitrate = IMX_I2C_BIT_RATE; > ret = of_property_read_u32(pdev->dev.of_node, > @@ -1056,9 +1069,8 @@ static int i2c_imx_probe(struct platform_device > *pdev) > goto clk_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); @@ > -1079,6 +1091,11 @@ 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 (IS_ERR_VALUE(ret)) > + return ret; > > /* remove adapter */ > dev_dbg(&i2c_imx->adapter.dev, "adapter removed\n"); @@ -1093,14 > +1110,51 @@ 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\n"); > + return ret; > + } > + > + return 0; > +} > + > +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, > + .pm = I2C_IMX_PM_OPS, > .of_match_table = i2c_imx_dt_ids, > }, > .id_table = imx_i2c_devtype, > -- > 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
