On 01/15/2014 01:50 AM, Eduardo Valentin wrote: > * PGP Signed by an unknown key > > On 14-01-2014 00:17, Wei Ni wrote: >> On 01/14/2014 05:33 AM, Eduardo Valentin wrote: >>>> Old Signed by an unknown key >>> >>> On 13-01-2014 15:01, Matthew Longnecker wrote: >>>> On 1/13/2014 7:42 AM, Eduardo Valentin wrote: >>>>>> This serie can support to turn governor for thermal zone in >>>>>> run time. >>>>> >>>>> Can you please explain why this is needed? Are you facing troubles with >>>>> current way to switch governors? If yes, can you please report them? >>> >>> Looks like there is a need to switch governors from within kernel code, >>> but not explanation of use cases is provided. >> >> In fact, with the of-thermal framework, the driver can't initialize to >> any governor, even default governor, it may be a bug. As we discussed in >> other mail list, we should not set governor in DT, and I think the >> platform driver should be able to set to any governors which it want, so >> I this patch, the driver can call the thermal_update_governor() to >> switch to new governor in kernel space. >> For example, there have two thermal driver, using of-thermal to register >> thermal zone device. One want to set to step_wise governor, another want >> fair_share, how can we do? I think after they calling the >> thermal_zone_of_sensor_register(), they can call the >> thermal_update_governor() to set the governor which they want. >> >>> >>>>> >>>> >>>> .... >>>> >>>>>> Adds thermal_update_governor() function, so the thermal platform >>>>>> driver can use it to update governor. >>>>> >>>>> Here I cannot see why the platform driver would need to update a >>>>> governor, instead of a zone. Platform drivers are not supposed to be >>>>> aware of governors. For updating a zone we already have an API for that, >>>>> please check documentation. >>>>> >>>> >>>> I think we have a miscommunication. The purpose of >>>> thermal_update_governor is to *switch* governors at runtime (from within >>>> the kernel). >>>> >>>> Wei has used the term "update" in the sense of switch rather than >>>> "update" in the sense used by thermal_zone_device_update. >>> >>> Fine, but why do you need it? >> >> Yes, I have consider to use "switch", but As my commit in the patch, in >> the future, the governor may be more complex, it may need governor >> parameter/configuration, and need to be tuned in run-time or in >> initialization. > > OK, I see you have a very complex governor coming. But you know, > prediction is very difficult, especially if it's about the future. :-) Yes, absolutely agree. > > It would be very constructive if you could share the governor together > with the proposed change. It is not fair to introduce a new API for a > non-existing user, don't you agree? > >> In fact we develop a new governor, based on PID logic. It will need some >> parameters, such as proportional, integral and derivative. these value >> will be initialized in different values for different thermal zone, so >> we want to use the thermal_zone_device_update() to switch governor or >> update the governor's parameters for different thermal zone. > > The parameters are a zone specific data right? Why should it be bound to > governor switch? The governor should be able to fetch the zone data when > needed. Let me consider it carefully again. > > Again, if you share the user of the API you are proposing we can work > together to make a better fit between API and users. > > For the existing governors, I don't see a need to have the stop and > start callbacks. > >> >>> >>>> >>>> Eduardo, what is your recommended technique for setting the governor of >>>> a thermal zone device created via device tree? >>> >>> So far the recommended (and existing) way is by user(land) decision. >>> >>>> >>>> thanks, >>>> Matt >>>> >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-pm" in >>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> >>>> >>> >>> >> >> >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
