[PATCH v9 2/4] amba: Don't unprepare the clocks if device driver wants IRQ safe runtime PM
From: Krzysztof Kozlowski <hidden>
Date: 2014-11-04 12:53:18
Also in:
lkml
Subsystem:
arm primecell bus support, the rest · Maintainers:
Russell King, Linus Torvalds
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 <redacted> --- drivers/amba/bus.c | 24 ++++++++++++++++++++---- include/linux/amba/bus.h | 1 + 2 files changed, 21 insertions(+), 4 deletions(-)
diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 47bbdc1b5be3..27ec8882ec8e 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c@@ -85,6 +85,13 @@ static struct device_attribute amba_dev_attrs[] = { }; #ifdef CONFIG_PM + +#ifdef CONFIG_PM_RUNTIME +#define get_pm_runtime_irq_safe(dev) ((dev)->power.irq_safe) +#else +#define get_pm_runtime_irq_safe(dev) 1 +#endif + /* * Hooks to provide runtime PM of the pclk (bus clock). It is safe to * enable/disable the bus clock at runtime PM suspend/resume as this
@@ -95,8 +102,14 @@ 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 = get_pm_runtime_irq_safe(dev); + + if (pcdev->irq_safe) + clk_disable(pcdev->pclk); + else + clk_disable_unprepare(pcdev->pclk); + } return ret; }
@@ -107,7 +120,10 @@ 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 +131,7 @@ 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