ARM: 8201/1: amba: Don't unprepare the clocks if device driver wants IRQ safe runtime...

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.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 47bbdc1b5be327ddf913f920d8b78cfc4f253a0c..f8e3bb44938e27bf619c05e81fb288f2a2775a35 100644 (file)
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -95,8 +95,12 @@ 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) {
+               if (pm_runtime_is_irq_safe(dev))
+                       clk_disable(pcdev->pclk);
+               else
+                       clk_disable_unprepare(pcdev->pclk);
+       }
 
        return ret;
 }
@@ -107,7 +111,10 @@ static int amba_pm_runtime_resume(struct device *dev)
        int ret;
 
        if (dev->driver) {
-               ret = clk_prepare_enable(pcdev->pclk);
+               if (pm_runtime_is_irq_safe(dev))
+                       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 +122,7 @@ 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,