On Monday, October 20, 2014 11:04:46 AM Krzysztof Kozlowski 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. > > Detect the device driver behavior after calling its probe function and > store it. During runtime suspend/resume deal with clocks according to > stored value. > > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx> > Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> > --- > drivers/amba/bus.c | 29 +++++++++++++++++++++++++---- > include/linux/amba/bus.h | 1 + > 2 files changed, 26 insertions(+), 4 deletions(-) > > diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c > index 47bbdc1b5be3..474434e1b1b9 100644 > --- a/drivers/amba/bus.c > +++ b/drivers/amba/bus.c > @@ -95,8 +95,18 @@ 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) { > + /* > + * Drivers should not change pm_runtime_irq_safe() > + * after probe. > + */ > + WARN_ON(pcdev->irq_safe != pm_runtime_is_irq_safe(dev)); > + > + if (pcdev->irq_safe) > + clk_disable(pcdev->pclk); > + else > + clk_disable_unprepare(pcdev->pclk); > + } > > return ret; > } > @@ -107,7 +117,16 @@ static int amba_pm_runtime_resume(struct device *dev) > int ret; > > if (dev->driver) { > - ret = clk_prepare_enable(pcdev->pclk); > + /* > + * Drivers should not change pm_runtime_irq_safe() > + * after probe. > + */ > + WARN_ON(pcdev->irq_safe != pm_runtime_is_irq_safe(dev)); > + > + if (pcdev->irq_safe) > + ret = clk_enable(pcdev->pclk); > + else > + ret = clk_prepare_enable(pcdev->pclk); > /* Failure is probably fatal to the system, but... */ > if (ret) > return ret; > @@ -198,8 +217,10 @@ static int amba_probe(struct device *dev) > pm_runtime_enable(dev); > > ret = pcdrv->probe(pcdev, id); > - if (ret == 0) > + if (ret == 0) { > + pcdev->irq_safe = pm_runtime_is_irq_safe(dev); This looks racy. Is it guaranteed that runtime PM callbacks won't be run for the device after pcdrv->probe() has returned and before setting pcdev->irq_safe? If not, inconsistent behavior may ensue. > break; > + } > > pm_runtime_disable(dev); > pm_runtime_set_suspended(dev); > diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h > index ac02f9bd63dc..c4bae79851fb 100644 > --- a/include/linux/amba/bus.h > +++ b/include/linux/amba/bus.h > @@ -32,6 +32,7 @@ struct amba_device { > struct clk *pclk; > unsigned int periphid; > unsigned int irq[AMBA_NR_IRQS]; > + unsigned int irq_safe:1; > }; > > struct amba_driver { > -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html