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@xxxxxxxxxxx>
---
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
--
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