On 01/15/2014 01:44 AM, Eduardo Valentin wrote: > * PGP Signed by an unknown key > > Hello Wei, > > 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 > > I see. Using default governor is not a bug. The thermal zone shall not > be defined in way that it is specific to a policy. We must remember that > DT is not used for specifying policies, but only describing hardware. > >> 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 > > OK. But still, because you believe the platform driver has to set the > governor, this is not a bug. Defining which policy is used to control a > zone can be a later decision in the boot process. Specially because the > critical requirements are not dealt by the governors anyway. > >> I this patch, the driver can call the thermal_update_governor() to >> switch to new governor in kernel space. > > I see. > >> 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. > > OK. Now I get a better view of what you are trying to achieve with this > series. However, why can't you hand this decision off to userland, > during, say very early boot sequence? I think the thermal_zone_device_register() provide a way to set governor when register a thermal zone, and this function is exposed to all driver, so I supposed the thermal framework can support to handle the governor in kernel. Anyway, let's consider to switch the governor in user space. > > >> >>> >>>>> >>>> >>>> .... >>>> >>>>>> 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. >> 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. >> >>> >>>> >>>> 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
