| Message ID | 1411566612-32277-4-git-send-email-k.kozlowski@samsung.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On 24 September 2014 15:50, Krzysztof Kozlowski <k.kozlowski@samsung.com> 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@samsung.com> As I stated earlier, I think the local copy of the irq_safe flag and the including WARN_ON is a bit unnecessary. Still since Russell insisted in having them, I am happy as well. :-) Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> Kind regards Uffe > --- > 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 3cf61a127ee5..e8fd5706954f 100644 > --- a/drivers/amba/bus.c > +++ b/drivers/amba/bus.c > @@ -94,8 +94,18 @@ 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; > } > @@ -106,7 +116,16 @@ 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; > @@ -191,8 +210,10 @@ 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); > 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 bb352d0bd737..fd0c0bfa1d38 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 { > -- > 1.9.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c index 3cf61a127ee5..e8fd5706954f 100644 --- a/drivers/amba/bus.c +++ b/drivers/amba/bus.c @@ -94,8 +94,18 @@ 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; } @@ -106,7 +116,16 @@ 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; @@ -191,8 +210,10 @@ 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); 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 bb352d0bd737..fd0c0bfa1d38 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 {
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@samsung.com> --- drivers/amba/bus.c | 29 +++++++++++++++++++++++++---- include/linux/amba/bus.h | 1 + 2 files changed, 26 insertions(+), 4 deletions(-)