| Message ID | 1415263010-7992-4-git-send-email-k.kozlowski@samsung.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
On 6 November 2014 09:36, 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 during runtime suspend. During runtime > resume deal with clocks according to stored value. > > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> > --- > drivers/amba/bus.c | 17 +++++++++++++---- > include/linux/amba/bus.h | 1 + > 2 files changed, 14 insertions(+), 4 deletions(-) > > diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c > index 47bbdc1b5be3..356f906c6966 100644 > --- a/drivers/amba/bus.c > +++ b/drivers/amba/bus.c > @@ -95,8 +95,14 @@ 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) { > + pcdev->irq_safe = dev->power.irq_safe; > + > + if (pcdev->irq_safe) > + clk_disable(pcdev->pclk); > + else > + clk_disable_unprepare(pcdev->pclk); > + } > > return ret; > } > @@ -107,7 +113,10 @@ static int amba_pm_runtime_resume(struct device *dev) > int ret; > > if (dev->driver) { > - ret = clk_prepare_enable(pcdev->pclk); > + 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; > @@ -115,7 +124,7 @@ 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, > 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 { > -- > 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
On Thursday, November 06, 2014 09:36:48 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 during runtime suspend. During runtime > resume deal with clocks according to stored value. > > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> > --- > drivers/amba/bus.c | 17 +++++++++++++---- > include/linux/amba/bus.h | 1 + > 2 files changed, 14 insertions(+), 4 deletions(-) > > diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c > index 47bbdc1b5be3..356f906c6966 100644 > --- a/drivers/amba/bus.c > +++ b/drivers/amba/bus.c > @@ -95,8 +95,14 @@ 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) { > + pcdev->irq_safe = dev->power.irq_safe; > + > + if (pcdev->irq_safe) > + clk_disable(pcdev->pclk); > + else > + clk_disable_unprepare(pcdev->pclk); > + } > > return ret; > } > @@ -107,7 +113,10 @@ static int amba_pm_runtime_resume(struct device *dev) > int ret; > > if (dev->driver) { > - ret = clk_prepare_enable(pcdev->pclk); > + 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; > @@ -115,7 +124,7 @@ 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, > 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; Why do we need the new flag? Seems redundant to me. > }; > > struct amba_driver { >
On czw, 2014-11-06 at 23:52 +0100, Rafael J. Wysocki wrote: > On Thursday, November 06, 2014 09:36:48 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 during runtime suspend. During runtime > > resume deal with clocks according to stored value. > > > > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> > > --- > > drivers/amba/bus.c | 17 +++++++++++++---- > > include/linux/amba/bus.h | 1 + > > 2 files changed, 14 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c > > index 47bbdc1b5be3..356f906c6966 100644 > > --- a/drivers/amba/bus.c > > +++ b/drivers/amba/bus.c > > @@ -95,8 +95,14 @@ 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) { > > + pcdev->irq_safe = dev->power.irq_safe; > > + > > + if (pcdev->irq_safe) > > + clk_disable(pcdev->pclk); > > + else > > + clk_disable_unprepare(pcdev->pclk); > > + } > > > > return ret; > > } > > @@ -107,7 +113,10 @@ static int amba_pm_runtime_resume(struct device *dev) > > int ret; > > > > if (dev->driver) { > > - ret = clk_prepare_enable(pcdev->pclk); > > + 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; > > @@ -115,7 +124,7 @@ 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, > > 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; > > Why do we need the new flag? Seems redundant to me. Some poorly written driver could set irq_safe somewhere between suspend and resume (e.g. in suspend callback). Best regards, Krzysztof -- 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
On Friday, November 07, 2014 09:01:09 AM Krzysztof Kozlowski wrote: > On czw, 2014-11-06 at 23:52 +0100, Rafael J. Wysocki wrote: > > On Thursday, November 06, 2014 09:36:48 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 during runtime suspend. During runtime > > > resume deal with clocks according to stored value. > > > > > > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> > > > --- > > > drivers/amba/bus.c | 17 +++++++++++++---- > > > include/linux/amba/bus.h | 1 + > > > 2 files changed, 14 insertions(+), 4 deletions(-) > > > > > > diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c > > > index 47bbdc1b5be3..356f906c6966 100644 > > > --- a/drivers/amba/bus.c > > > +++ b/drivers/amba/bus.c > > > @@ -95,8 +95,14 @@ 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) { > > > + pcdev->irq_safe = dev->power.irq_safe; > > > + > > > + if (pcdev->irq_safe) > > > + clk_disable(pcdev->pclk); > > > + else > > > + clk_disable_unprepare(pcdev->pclk); > > > + } > > > > > > return ret; > > > } > > > @@ -107,7 +113,10 @@ static int amba_pm_runtime_resume(struct device *dev) > > > int ret; > > > > > > if (dev->driver) { > > > - ret = clk_prepare_enable(pcdev->pclk); > > > + 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; > > > @@ -115,7 +124,7 @@ 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, > > > 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; > > > > Why do we need the new flag? Seems redundant to me. > > Some poorly written driver could set irq_safe somewhere between suspend > and resume (e.g. in suspend callback). It could also modify your bus type irq_safe flag to hide the fact. In my opinion, it doesn't really help. Rafael -- 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 47bbdc1b5be3..356f906c6966 100644 --- a/drivers/amba/bus.c +++ b/drivers/amba/bus.c @@ -95,8 +95,14 @@ 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) { + pcdev->irq_safe = dev->power.irq_safe; + + if (pcdev->irq_safe) + clk_disable(pcdev->pclk); + else + clk_disable_unprepare(pcdev->pclk); + } return ret; } @@ -107,7 +113,10 @@ static int amba_pm_runtime_resume(struct device *dev) int ret; if (dev->driver) { - ret = clk_prepare_enable(pcdev->pclk); + 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; @@ -115,7 +124,7 @@ 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, 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 {
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 during runtime suspend. During runtime resume deal with clocks according to stored value. Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> --- drivers/amba/bus.c | 17 +++++++++++++---- include/linux/amba/bus.h | 1 + 2 files changed, 14 insertions(+), 4 deletions(-)