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Hi Alan, Thanks for quick replies. As you said > >> 2) Suppose device is active, means its power_usage counter is already one, Now during system > >> sleep, does the driver first suspend it with run time power management core and then continue > >> System suspend? > > {ALAN} No. But since during system suspend power_usage counter is incremented by 1 But if the device is active means its state is RPM_ACTIVE, its power_usage counter is 1 in run time power management core. when the system suspend happens, it will also increment the power_usage_counter by 1 during dpm_prepare Now the power_usage_counter is 2. So when dpm_complete is invoked, it will decrement the power_usage_counter by 1 during dpm_complete. So now when the drivers gets system suspend, its power_usage counter is still 1. So what in this scenario, does the device decrements the power_usage counter itself? Thanks Raj > > > > ---------------------------------------- > > Date: Tue, 24 Aug 2010 10:30:25 -0400 > > From: stern@xxxxxxxxxxxxxxxxxxx > > To: rajkumar278@xxxxxxxxxxx > > CC: linux-kernel@xxxxxxxxxxxxxxx > > Subject: Re: Runtime power management during system resume > > > > On Tue, 24 Aug 2010, Raj Kumar wrote: > > > >> Hi Alan, > >> > >> I have implemented the run time power management in my drivers. I have one > >> issue regarding System resume. > >> > >> When the system sleep is triggered as it is mentioned that Power management > >> core will increment the power_usage counter during prepare and decrements when complete > >> is called. > >> > >> Now I have few questions: > >> > >> 1) When the system resume is done, it does not increase the power_usage counter. > >> right? > > > > That's right. > > > >> So Does then the driver need to update the power_usage counter with run time power management > >> core and again set it to active means RPM_ACTIVE? > > > > Read section 6 of Documentation/power/runtime_pm.h. It explains this. > > > >> 2) Suppose device is active, means its power_usage counter is already one, Now during system > >> sleep, does the driver first suspend it with run time power management core and then continue > >> System suspend? > > > > No. > > > >> 3) Because I have seen the code of power management core and I did not see the that during > >> system suspend, run time power management status is updated means RPM_SUSPENDED. > >> right? > > > > I don't understand your question. > > > > Alan Stern > > |
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