pm runtime and system suspend resume
stern at rowland.harvard.edu
Tue Jun 19 10:48:22 EDT 2012
On Tue, 19 Jun 2012, chao xie wrote:
> PM_RUNTIME provide a way for device driver do runtime PM. so for some
> devices, they have some surrounded logic. For example, the device may
> get clock from outside, or it need PHY support(USB is a example).
> To get these dependency out of device driver, i define a struct
> dev_pm_domain, and make dev.pm_domain point to it. So in the device
> driver, when the hardware should be enabled, we can call
> pm_runtime_get_sync while when the hardware is idle or does not work,
> we can call pm_runtime_put_sync.
> It seems work well, but i have question about the suspend/resume of
> device. When the whole system will go to deep idle, and it will
> suspend the devices. for the function do device suspend
What source file is that function in?
> it will call pm_runtime_get_noresume(dev). As i
> think it will make the device not do runtime suspend any more. Is that
It sounds wrong. Why would a suspend routine do that?
> There is the question, how device driver handle the logic surrounds
> it? I want to add pm_runtime_put_sync in dev->driver->pm->suspend
> function, and pm_runtime_get_sync in dev->driver->pm->resume.
You must not do that. If you do, your driver will hang.
> __device_suspend increase the usage_count, pm_runtime_put_sync will
> not do real work.
> So is that right that i directly call pm_runtime_suspend in
> dev->driver->pm->suspend and pm_runtime_resume in
No, it works the other way around. pm_runtime_suspend calls
dev->driver->pm->suspend, and pm_runtime_resume calls
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