Re: [PATCH v4 1/2] i2c: davinci: Add PM Runtime Support

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Hi,

On 12 September 2017 at 04:11, Franklin S Cooper Jr <fcooper@xxxxxx> wrote:
> 66AK2G has I2C instances that are not apart of the ALWAYS_ON power domain
> unlike other Keystone 2 SoCs and OMAPL138. Therefore, pm_runtime
> is required to insure the power domain used by the specific I2C instance is
> properly turned on along with its functional clock.
>
> Signed-off-by: Franklin S Cooper Jr <fcooper@xxxxxx>
> ---
> Version 4 changes:
> Fix wording on error message
> Fix additional error path
>
> Version 3 changes:
> Remove several statements that set clk to NULL
> Fix error path
>
>  drivers/i2c/busses/i2c-davinci.c | 67 +++++++++++++++++++++++++++++++++-------
>  1 file changed, 55 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
> index b8c4353..a2d9f7c 100644
> --- a/drivers/i2c/busses/i2c-davinci.c
> +++ b/drivers/i2c/busses/i2c-davinci.c
> @@ -36,6 +36,7 @@
>  #include <linux/gpio.h>
>  #include <linux/of_device.h>
>  #include <linux/platform_data/i2c-davinci.h>
> +#include <linux/pm_runtime.h>
>
>  /* ----- global defines ----------------------------------------------- */
>
> @@ -122,6 +123,9 @@
>  /* set the SDA GPIO low */
>  #define DAVINCI_I2C_DCLR_PDCLR1        BIT(1)
>
> +/* timeout for pm runtime autosuspend */
> +#define DAVINCI_I2C_PM_TIMEOUT 1000    /* ms */
> +
>  struct davinci_i2c_dev {
>         struct device           *dev;
>         void __iomem            *base;
> @@ -541,10 +545,17 @@ i2c_davinci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>
>         dev_dbg(dev->dev, "%s: msgs: %d\n", __func__, num);
>
> +       ret = pm_runtime_get_sync(dev->dev);
> +       if (ret < 0) {
> +               dev_err(dev->dev, "Failed to runtime_get device: %d\n", ret);
> +               pm_runtime_put_noidle(dev->dev);
> +               return ret;
> +       }
> +
>         ret = i2c_davinci_wait_bus_not_busy(dev);
>         if (ret < 0) {
>                 dev_warn(dev->dev, "timeout waiting for bus ready\n");
> -               return ret;
> +               goto out;
>         }
>
>         for (i = 0; i < num; i++) {
> @@ -552,14 +563,19 @@ i2c_davinci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>                 dev_dbg(dev->dev, "%s [%d/%d] ret: %d\n", __func__, i + 1, num,
>                         ret);
>                 if (ret < 0)
> -                       return ret;
> +                       goto out;
>         }
>
> +       ret = num;
>  #ifdef CONFIG_CPU_FREQ
>         complete(&dev->xfr_complete);
>  #endif
>
> -       return num;
> +out:
> +       pm_runtime_mark_last_busy(dev->dev);
> +       pm_runtime_put_autosuspend(dev->dev);
> +
> +       return ret;
>  }
>
>  static u32 i2c_davinci_func(struct i2c_adapter *adap)
> @@ -599,6 +615,9 @@ static irqreturn_t i2c_davinci_isr(int this_irq, void *dev_id)
>         int count = 0;
>         u16 w;
>
> +       if (pm_runtime_suspended(dev->dev))
> +               return IRQ_NONE;
> +
>         while ((stat = davinci_i2c_read_reg(dev, DAVINCI_I2C_IVR_REG))) {
>                 dev_dbg(dev->dev, "%s: stat=0x%x\n", __func__, stat);
>                 if (count++ == 100) {
> @@ -802,13 +821,24 @@ static int davinci_i2c_probe(struct platform_device *pdev)
>         dev->clk = devm_clk_get(&pdev->dev, NULL);
>         if (IS_ERR(dev->clk))
>                 return PTR_ERR(dev->clk);
> -       clk_prepare_enable(dev->clk);

You removed clk enable here, I think it can not work if we did not
open CONFIG_PM macro. I think you should keep clk enable here, and set
rpm active by pm_runtime_set_active() before issuing
pm_runtime_enable().

>
>         mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>         dev->base = devm_ioremap_resource(&pdev->dev, mem);
>         if (IS_ERR(dev->base)) {
> -               r = PTR_ERR(dev->base);
> -               goto err_unuse_clocks;
> +               return PTR_ERR(dev->base);
> +       }
> +
> +       pm_runtime_set_autosuspend_delay(dev->dev,
> +                                        DAVINCI_I2C_PM_TIMEOUT);
> +       pm_runtime_use_autosuspend(dev->dev);
> +
> +       pm_runtime_enable(dev->dev);
> +
> +       r = pm_runtime_get_sync(dev->dev);
> +       if (r < 0) {
> +               dev_err(dev->dev, "failed to runtime_get device: %d\n", r);
> +               pm_runtime_put_noidle(dev->dev);
> +               return r;
>         }
>
>         i2c_davinci_init(dev);
> @@ -849,27 +879,40 @@ static int davinci_i2c_probe(struct platform_device *pdev)
>         if (r)
>                 goto err_unuse_clocks;
>
> +       pm_runtime_mark_last_busy(dev->dev);
> +       pm_runtime_put_autosuspend(dev->dev);
> +
>         return 0;
>
>  err_unuse_clocks:
> -       clk_disable_unprepare(dev->clk);
> -       dev->clk = NULL;
> +       pm_runtime_dont_use_autosuspend(dev->dev);
> +       pm_runtime_put_sync(dev->dev);
> +       pm_runtime_disable(dev->dev);
> +
>         return r;
>  }
>
>  static int davinci_i2c_remove(struct platform_device *pdev)
>  {
>         struct davinci_i2c_dev *dev = platform_get_drvdata(pdev);
> +       int ret;
>
>         i2c_davinci_cpufreq_deregister(dev);
>
>         i2c_del_adapter(&dev->adapter);
>
> -       clk_disable_unprepare(dev->clk);
> -       dev->clk = NULL;
> +       ret = pm_runtime_get_sync(&pdev->dev);
> +       if (ret < 0) {
> +               pm_runtime_put_noidle(&pdev->dev);
> +               return ret;
> +       }
>
>         davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, 0);
>
> +       pm_runtime_dont_use_autosuspend(dev->dev);
> +       pm_runtime_put_sync(dev->dev);
> +       pm_runtime_disable(dev->dev);
> +
>         return 0;
>  }
>
> @@ -880,7 +923,6 @@ static int davinci_i2c_suspend(struct device *dev)
>
>         /* put I2C into reset */
>         davinci_i2c_reset_ctrl(i2c_dev, 0);
> -       clk_disable_unprepare(i2c_dev->clk);
>
>         return 0;
>  }
> @@ -889,7 +931,6 @@ static int davinci_i2c_resume(struct device *dev)
>  {
>         struct davinci_i2c_dev *i2c_dev = dev_get_drvdata(dev);
>
> -       clk_prepare_enable(i2c_dev->clk);
>         /* take I2C out of reset */
>         davinci_i2c_reset_ctrl(i2c_dev, 1);
>
> @@ -899,6 +940,8 @@ static int davinci_i2c_resume(struct device *dev)
>  static const struct dev_pm_ops davinci_i2c_pm = {
>         .suspend        = davinci_i2c_suspend,
>         .resume         = davinci_i2c_resume,
> +       SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> +                                     pm_runtime_force_resume)
>  };
>
>  #define davinci_i2c_pm_ops (&davinci_i2c_pm)
> --
> 2.9.4.dirty
>



-- 
Baolin.wang
Best Regards
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