ARM: 8201/1: amba: Don't unprepare the clocks if device driver wants IRQ safe runtime...
authorKrzysztof Kozlowski <k.kozlowski@samsung.com>
Fri, 14 Nov 2014 08:48:27 +0000 (09:48 +0100)
committerRussell King <rmk+kernel@arm.linux.org.uk>
Mon, 17 Nov 2014 20:23:36 +0000 (20:23 +0000)
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>
drivers/amba/bus.c

index 47bbdc1b5be327ddf913f920d8b78cfc4f253a0c..f8e3bb44938e27bf619c05e81fb288f2a2775a35 100644 (file)
@@ -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,