> > I am required to put some external device (led brightness) into > minimal brightness when the system gets to idle. Please elaborate on "System gets to idle state." Do you mean the system is suspended ? ------- case 1 or the device has moved to idle state? ------- case 2 > The control on led brightness value is done as part of dedicated > character device which was written for the purpose of brightness > control (which uses i2c bus) > I wander if this is possible using the linux PM capabilities, and how > this should be done. In either case it should be possible as per my understanding. You need to implement it in the appropriate PM handlers. case1 ----> write the appropriate code in driver->pm->suspend case2 ----> write the appropriate code in driver->pm->runtime_idle Regards, Ayan Kumar Halder > Thanks, > Ran > > On Fri, Sep 5, 2014 at 7:13 PM, AYAN KUMAR HALDER <ayankumarh@xxxxxxxxx> wrote: >>> When adding some external device to power management, doesn't it need >>> to belong to power domain ( /debug/pm_debug/count ). >> >> Power Domains are decided by system designer. A board can be divided >> into multiple power domains which can be powered on/off or >> voltage/current regulated independently as each power domain is >> controlled by a power regulator. >> >>> What is the power domain of external device ? >> The right person to answer this question will be your system designer. >> You may look into the board schematics to find out power regulator of >> your external device. Each power domain is controlled by a power >> regulator. >> >> It is not necessary for you to consider power domains if you do not >> wish to power up/down or regulate the voltage /current while running >> Linux on the board. Another generic way to do runtime-power management >> of various devices would be to perform clock scaling/gating (assuming >> you know the clock domains of your system). _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
