From 588eb93ea49f672cb3ff55d0a5c34df3e1afa7ec Mon Sep 17 00:00:00 2001 From: Gao Pan Date: Fri, 11 Dec 2015 10:24:09 +0800 Subject: i2c: imx: add runtime pm support to improve the performance MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Gao Pan Acked-by: Uwe Kleine-König [wsa: sorted includes] Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-imx.c | 90 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 78 insertions(+), 12 deletions(-) (limited to 'drivers/i2c/busses/i2c-imx.c') diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index d4d8536..3ffdcf4 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -53,6 +53,7 @@ #include #include #include +#include #include #include @@ -120,6 +121,8 @@ #define I2CR_IEN_OPCODE_0 0x0 #define I2CR_IEN_OPCODE_1 I2CR_IEN +#define I2C_PM_TIMEOUT 10 /* ms */ + /** Variables ****************************************************************** *******************************************************************************/ @@ -527,9 +530,6 @@ 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); @@ -582,7 +582,6 @@ 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) @@ -901,6 +900,10 @@ 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) { @@ -964,6 +967,10 @@ 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); @@ -1083,7 +1090,7 @@ 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; } @@ -1107,6 +1114,18 @@ 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, @@ -1125,12 +1144,11 @@ 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); @@ -1143,6 +1161,12 @@ 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; @@ -1151,6 +1175,11 @@ 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"); @@ -1165,17 +1194,54 @@ 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) -- cgit v1.1