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>
---
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 ad52027a9cbf..ce101e4497d6 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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