Hi Pavel, On 19. 3. 7. 오전 8:10, Pavel Machek wrote: > On Fri 2019-01-25 14:54:03, Marek Szyprowski wrote: >> This way devfreq core ensures that all its devices will be set to safe >> operation points before reboot operation. There are board on which some >> aggressive power saving operation points are behind the capabilities of >> the bootloader to properly reset the hardware and boot the board. This >> way one can avoid board crash early after reboot. >> >> Similar pattern is used in CPUfreq subsystem. > > This looks somehow dangerous to me. I guess this will break someone's > shutdown, and on battery-powered devices, that's quite bad thing to > do. This patch executes the devfreq_suspend() for all devfreq devices. The devfreq_suspend() does the following: 1. (mandatory) stop the polling of governor. 2. (optional) If devfreq device specifies the 'opp-suspend' property in DT, the devfreq changes the frequency by using the devfreq->suspend_freq. If the user of devfreq device doesn't want to change the frequency during the system shutdown, just don't add the 'opp-suspend' property in DT. And the devfreq_suspend() will just stop the polling for governor. Even if on battery-powered devices, I think it is not problem to stop the polling of governor during the system shutdown. In my case, I don't know what is dangerous. Could you explain it more detailed. > > Could we explicitely do it only for devices that need it? > Pavel > > -- Best Regards, Chanwoo Choi Samsung Electronics
