in order to make HWMOD and pm_runtime agree on the
initial state of the device, we will unidle the device
and call pm_runtime_set_active() to tell pm_runtime
that the device is really active.

By the time driver's probe() is reached, a call to
pm_runtime_get_sync() will not cause driver's
->runtime_resume() method to be called at first, only
after a successful ->runtime_suspend().

Note that we must prevent pm_runtime transitions while
driver is probing otherwise drivers would be suspended
as soon as they call pm_runtime_use_autosuspend(). By
calling pm_runtime_forbid() before probe() and
pm_runtime_allow() after probe() we 'fix' that detail.

Note that this patch was inspired by PCI's pci_pm_init().

Signed-off-by: Felipe Balbi <ba...@ti.com>
---

boot tested on top of today's Linus master
6d128e1e72bf082542e85f72e6b7ddd704193588 with OMAP4
panda. Reached console prompt and, after setting a
proper autosuspend delay, consoles autosuspend just
fine.

It needs to be tested on other platforms.

ps: note that we also call pm_runtime_set_suspended(dev)
from our late_initcall() to disable devices so that pm_runtime
and HWMOD continue to aggree on device's state.

 arch/arm/mach-omap2/omap_device.c | 44 +++++++++++++++++++++++++++++++++++----
 1 file changed, 40 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-omap2/omap_device.c 
b/arch/arm/mach-omap2/omap_device.c
index 5cc9287..cb1fc1d 100644
--- a/arch/arm/mach-omap2/omap_device.c
+++ b/arch/arm/mach-omap2/omap_device.c
@@ -178,6 +178,26 @@ odbfd_exit:
        return ret;
 }
 
+static void omap_device_pm_init(struct platform_device *pdev)
+{
+       omap_device_enable(pdev);
+       pm_runtime_forbid(&pdev->dev);
+       pm_runtime_set_active(&pdev->dev);
+       device_enable_async_suspend(&pdev->dev);
+}
+
+static void omap_device_pm_allow(struct platform_device *pdev)
+{
+       pm_runtime_allow(&pdev->dev);
+}
+
+static void omap_device_pm_exit(struct platform_device *pdev)
+{
+       device_disable_async_suspend(&pdev->dev);
+       pm_runtime_set_suspended(&pdev->dev);
+       omap_device_idle(pdev);
+}
+
 static int _omap_device_notifier_call(struct notifier_block *nb,
                                      unsigned long event, void *dev)
 {
@@ -189,16 +209,31 @@ static int _omap_device_notifier_call(struct 
notifier_block *nb,
                if (pdev->archdata.od)
                        omap_device_delete(pdev->archdata.od);
                break;
+       case BUS_NOTIFY_BIND_DRIVER:
+               if (pdev->archdata.od)
+                       omap_device_pm_init(pdev);
+               break;
+       case BUS_NOTIFY_BOUND_DRIVER:
+               if (pdev->archdata.od)
+                       omap_device_pm_allow(pdev);
+               break;
+       case BUS_NOTIFY_UNBOUND_DRIVER:
+               if (pdev->archdata.od)
+                       omap_device_pm_exit(pdev);
+               break;
        case BUS_NOTIFY_ADD_DEVICE:
                if (pdev->dev.of_node)
                        omap_device_build_from_dt(pdev);
-               /* fall through */
+               break;
        default:
-               od = to_omap_device(pdev);
-               if (od)
-                       od->_driver_status = event;
+               /* nothing */
+               break;
        }
 
+       od = to_omap_device(pdev);
+       if (od)
+               od->_driver_status = event;
+
        return NOTIFY_DONE;
 }
 
@@ -855,6 +890,7 @@ static int __init omap_device_late_idle(struct device *dev, 
void *data)
                        dev_warn(dev, "%s: enabled but no driver.  Idling\n",
                                 __func__);
                        omap_device_idle(pdev);
+                       pm_runtime_set_suspended(dev);
                }
        }
 
-- 
1.8.2.1

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