On Mon, Sep 19, 2011 at 10:14 AM, Sunil Pillai <sunilpillai....@gmail.com> wrote: > > Hi Pavan, > > Usual Linux PM would follow the below steps: > 1) Freezing Tasks [enter_state() calls suspend_prepare() which calls > suspend_freeze_processes()]
Stopping you right here, Because of the answer, PM_SUSPEND_PREPARE is before the user space is frozen. I suppose a few drivers are already doing this (example mmc)..... Although I will let someone else comment on this.... > 2) each driver's suspend routine is then invoked (In this case wifi > driver's suspend gets called here) > 3) This is followed by calling device suspend routines move devices to > low power mode > > However as you pointed in case of Android, before all above steps > happen, the early suspend routines of drivers get called & a check is > made to see if any wakelocks are held. (echo mem > /sys/power/state > from PowerManagerService) If no wakelocks are held only then the usual > linux routine described above is then followed. > > So to answer your questions: > 1. Android power management gets into action first by calling early > suspend routines & checks if any wakelocks are held which can block > the suspend resume. [So the userspace wifi daemon cannot hold a > wakelock here because it will not let the first step of suspend > routine take place. Its not premature for this to happen in this case] > > 2.Secondly, following normal linux suspend routine, Freezing of > processes takes place. [Thus the userspace wifi daemon also gets > freezed here to ram since no wakelocks are held by PowerManagerService > or any other module] > > 3. Now the wifi driver specific suspend routine gets invoked. But as I > discussed it cannot finish on time since it has to post a message to > the userspace wifi daemon to move it to the proper state) > In this case since the userspace wifi daemon is already freezed in > step(2) above, the driver's suspend doesnot complete on time given by > android to finish the device suspend routine. > > Hence, I'm looking for a way to see if the use space daemon in this > case can somehow be marked as non-freezable task.I'm not sure if there > is a proper way in which this situation can be handled!! > > Hope this makes my problem more clear. > > Regards, > Sunil > > > > On Sep 19, 4:46 pm, Pavan Savoy <pavan.sa...@gmail.com> wrote: >> On Mon, Sep 19, 2011 at 6:42 AM, Sunil Pillai <sunilpillai....@gmail.com> >> wrote: >> >> > Hello All, >> >> > I have this situation in my system where the android kernel suspend >> > procedure fails due to below sequence: >> >> > 1. suspend invoked by the android >> > 2. All user space processses get freezed including my android >> > userspace deamon process-X which has wifi userspace component >> >> Shouldn't this be happening, only if the "suspend" is a success ? >> Seems like the "freezing all process" - is happening prematurely in this >> case ? >> >> Also, the user-space process can always register/communicate with >> PowerManagerService in Android - to prevent suspend - wake-lock unless >> the WiFi - tells that it is alright to go into suspend. >> >> >> >> >> >> >> >> >> >> > 3. Wifi suspend driver gets trigerred; But this in has to call a >> > routine in userspace process-X (to suspend userspace Wifi component) >> > which is already freezed and this call (sync call) times out after >> > some time(10 ms) >> >> > This basically fails the suspend procedure for the Wifi driver. A >> > possible solution I feel is that the userspace process-X doesnot get >> > freezed unless the Wifi driver suspends itself successfully (including >> > suspending the userspace Wifi component) >> >> > Is this possible & if not how can I handle such a situation? >> >> > Regards, >> > Sunil >> >> > -- >> > unsubscribe: android-kernel+unsubscr...@googlegroups.com >> > website:http://groups.google.com/group/android-kernel >> >> -- >> --Pavan Savoy > > -- > unsubscribe: android-kernel+unsubscr...@googlegroups.com > website: http://groups.google.com/group/android-kernel -- --Pavan Savoy -- unsubscribe: android-kernel+unsubscr...@googlegroups.com website: http://groups.google.com/group/android-kernel
