Re: [PATCH v11 3/6] amba: Don't unprepare the clocks if device driver wants IRQ safe runtime PM

[Ulf Hansson]

On 12 November 2014 15:32, Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx> wrote:
> The AMBA bus driver defines runtime Power Management functions which
> disable and unprepare AMBA bus clock. This is problematic for runtime PM
> because unpreparing a clock might sleep so it is not interrupt safe.
>
> However some drivers may want to implement runtime PM functions in
> interrupt-safe way (see pm_runtime_irq_safe()). In such case the AMBA
> bus driver should only disable/enable the clock in runtime suspend and
> resume callbacks.
>
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>

Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>

> ---
>  drivers/amba/bus.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index a4ac490dd784..c2153a1d1981 100644
> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -95,8 +95,12 @@ static int amba_pm_runtime_suspend(struct device *dev)
>         struct amba_device *pcdev = to_amba_device(dev);
>         int ret = pm_generic_runtime_suspend(dev);
>
> -       if (ret == 0 && dev->driver)
> -               clk_disable_unprepare(pcdev->pclk);
> +       if (ret == 0 && dev->driver) {
> +               if (pm_runtime_is_irq_safe(dev))
> +                       clk_disable(pcdev->pclk);
> +               else
> +                       clk_disable_unprepare(pcdev->pclk);
> +       }
>
>         return ret;
>  }
> @@ -107,7 +111,10 @@ static int amba_pm_runtime_resume(struct device *dev)
>         int ret;
>
>         if (dev->driver) {
> -               ret = clk_prepare_enable(pcdev->pclk);
> +               if (pm_runtime_is_irq_safe(dev))
> +                       ret = clk_enable(pcdev->pclk);
> +               else
> +                       ret = clk_prepare_enable(pcdev->pclk);
>                 /* Failure is probably fatal to the system, but... */
>                 if (ret)
>                         return ret;
> @@ -115,7 +122,7 @@ static int amba_pm_runtime_resume(struct device *dev)
>
>         return pm_generic_runtime_resume(dev);
>  }
> -#endif
> +#endif /* CONFIG_PM */
>
>  static const struct dev_pm_ops amba_pm = {
>         .suspend        = pm_generic_suspend,
> --
> 1.9.1
>
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