[PATCH 04/13] coresight: tpiu: let runtime PM handle core clock

[Ulf Hansson]

On 17 April 2015 at 10:58, Linus Walleij <linus.walleij at linaro.org> wrote:
> This uses runtime PM to manage the PCLK ("amba_pclk") instead
> of screwing around with the framework by going in and taking
> a copy from the amba device. The amba bus core will uprepare
> and disable the clock when the device is unused when
> CONFIG_PM is selected, else the clock will be always on.
>
> Prior to this patch, as the AMBA primecell bus code enables
> the PCLK, it would be left on after probe as
> the clk_prepare_enable() and clk_disable_unprepare() was
> called and thus just increase and decreas the refcount by
> one, without it reaching zero and actually disabling the
> clock. Now the runtime PM callbacks will make sure the PCLK
> is properly disabled after probe.
>
> Signed-off-by: Linus Walleij <linus.walleij at linaro.org>

Reviewed-by: Ulf Hansson <ulf.hansson at linaro.org>

> ---
>  drivers/coresight/coresight-tpiu.c | 21 ++++-----------------
>  1 file changed, 4 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/coresight/coresight-tpiu.c b/drivers/coresight/coresight-tpiu.c
> index 88b6b0c32538..688ba937069e 100644
> --- a/drivers/coresight/coresight-tpiu.c
> +++ b/drivers/coresight/coresight-tpiu.c
> @@ -17,7 +17,7 @@
>  #include <linux/io.h>
>  #include <linux/err.h>
>  #include <linux/slab.h>
> -#include <linux/clk.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/coresight.h>
>  #include <linux/amba/bus.h>
>
> @@ -51,13 +51,11 @@
>   * @base:      memory mapped base address for this component.
>   * @dev:       the device entity associated to this component.
>   * @csdev:     component vitals needed by the framework.
> - * @clk:       the clock this component is associated to.
>   */
>  struct tpiu_drvdata {
>         void __iomem            *base;
>         struct device           *dev;
>         struct coresight_device *csdev;
> -       struct clk              *clk;
>  };
>
>  static void tpiu_enable_hw(struct tpiu_drvdata *drvdata)
> @@ -72,12 +70,8 @@ static void tpiu_enable_hw(struct tpiu_drvdata *drvdata)
>  static int tpiu_enable(struct coresight_device *csdev)
>  {
>         struct tpiu_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> -       int ret;
> -
> -       ret = clk_prepare_enable(drvdata->clk);
> -       if (ret)
> -               return ret;
>
> +       pm_runtime_get_sync(csdev->dev.parent);
>         tpiu_enable_hw(drvdata);
>
>         dev_info(drvdata->dev, "TPIU enabled\n");
> @@ -101,8 +95,7 @@ static void tpiu_disable(struct coresight_device *csdev)
>         struct tpiu_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
>
>         tpiu_disable_hw(drvdata);
> -
> -       clk_disable_unprepare(drvdata->clk);
> +       pm_runtime_put(csdev->dev.parent);
>
>         dev_info(drvdata->dev, "TPIU disabled\n");
>  }
> @@ -118,7 +111,6 @@ static const struct coresight_ops tpiu_cs_ops = {
>
>  static int tpiu_probe(struct amba_device *adev, const struct amba_id *id)
>  {
> -       int ret;
>         void __iomem *base;
>         struct device *dev = &adev->dev;
>         struct coresight_platform_data *pdata = NULL;
> @@ -148,15 +140,10 @@ static int tpiu_probe(struct amba_device *adev, const struct amba_id *id)
>
>         drvdata->base = base;
>
> -       drvdata->clk = adev->pclk;
> -       ret = clk_prepare_enable(drvdata->clk);
> -       if (ret)
> -               return ret;
> -
>         /* Disable tpiu to support older devices */
>         tpiu_disable_hw(drvdata);
>
> -       clk_disable_unprepare(drvdata->clk);
> +       pm_runtime_put(&adev->dev);
>
>         desc = devm_kzalloc(dev, sizeof(*desc), GFP_KERNEL);
>         if (!desc)
> --
> 1.9.3
>