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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