"Menon, Nishanth" <nm@xxxxxx> writes: > On Wed, May 30, 2012 at 12:59 PM, Kevin Hilman <khilman@xxxxxx> wrote: >> "Menon, Nishanth" <nm@xxxxxx> writes: >> >>> On Thu, May 17, 2012 at 3:52 AM, Shilimkar, Santosh >>> <santosh.shilimkar@xxxxxx> wrote: >>>> On Thu, May 17, 2012 at 12:34 PM, Shilimkar, Santosh >>>> <santosh.shilimkar@xxxxxx> wrote: >>>>> On Thu, May 17, 2012 at 4:12 AM, Kevin Hilman <khilman@xxxxxx> wrote: >>>>>> Tero Kristo <t-kristo@xxxxxx> writes: >>>>>> >>> [...] >>>>>> - Rather than hooking into omap4_enter_lowpower(), should use >>>>>> the cluster PM enter/exit notifier chain. >>>>>> >>>>> This is again specific to device OFF only and not related to CPU >>>>> cluster state as such. So I don't think notifiers should be used here. >>>>> >>>>> O.w even when we attempt just MPU OSWR C-state, all these functions will >>>>> get called in notifier chain. >>>>> >>>> Just a thought, we can have a separate notifier chain for device OFF. It can >>>> allow use to get rid of 'enable_off_mode" kind of flags and can be >>>> used by many drivers too. >>> >>> Like the overall idea, but one minor dumb concern might be sequencing >>> of notifiers >>> - OFF entry and restore needs things to be executed in a specific sequence. >>> How do we plan to ensure the sequence is maintained in a notifier call >>> chain? one >>> possible option might be a "priority" based scheme? >> >> Or just combine the events that need a specific sequence into single >> notifier callback function. > There is other issues in case of failure cases -> abort of OFF > sequence due to pending interrupt > detected as part of a notifier - error handling needs to be sane in > proper sequence. > I understand and appreciate the intent of replacing the single mega > enter_sleep with a chain of notifiers > but any such option will need to be scalable enough to handle weird > erratum handling (HSI CAWAKE as an example) > which potentially break the logic flow and be either be equal or > better than what we have today interms of > error handling. since these notifiers will be triggered for > CPUIDLE(performance sensitive) and suspend, the intricacies > might be better understood by seeing how this proposed notifiers look like. Makes sense. Thanks for clarifying. What $SUBJECT series proposed was indeed a "mega function", but one that was just a list of function calls with no error checking or recovery, and no documentation/description about dependencies/sequencing etc. etc. Based on the patches at hadn (which is all reviewers have to go on), notifiers seemed to be a good fit. If there are good reasons that all of the device-off events need to be coordinated/synchronized/sequenced (and it sounds like there are, thanks for pointing them out), I am not opposed to that approach. It simply needs to be well described in the changlog. Thanks, Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
