Hi Dongsheng, On 07/31/2013 11:16 AM, Wang Dongsheng-B40534 wrote: > Hi Preeti, > >> -----Original Message----- >> From: Preeti U Murthy [mailto:pre...@linux.vnet.ibm.com] >> Sent: Wednesday, July 31, 2013 12:00 PM >> To: Wang Dongsheng-B40534 >> Cc: Deepthi Dharwar; b...@kernel.crashing.org; daniel.lezc...@linaro.org; >> linux-ker...@vger.kernel.org; mich...@ellerman.id.au; >> srivatsa.b...@linux.vnet.ibm.com; sva...@linux.vnet.ibm.com; linuxppc- >> d...@lists.ozlabs.org; r...@sisk.pl; linux...@vger.kernel.org >> Subject: Re: [PATCH V2 4/6] cpuidle/pseries: Move the pseries_idle >> backend driver to sysdev. >> >> Hi Dongsheng, >> >> On 07/31/2013 08:52 AM, Wang Dongsheng-B40534 wrote: >>> >>> >>>> -----Original Message----- >>>> From: Deepthi Dharwar [mailto:deep...@linux.vnet.ibm.com] >>>> Sent: Wednesday, July 31, 2013 10:59 AM >>>> To: b...@kernel.crashing.org; daniel.lezc...@linaro.org; linux- >>>> ker...@vger.kernel.org; mich...@ellerman.id.au; >>>> srivatsa.b...@linux.vnet.ibm.com; pre...@linux.vnet.ibm.com; >>>> sva...@linux.vnet.ibm.com; linuxppc-dev@lists.ozlabs.org >>>> Cc: r...@sisk.pl; Wang Dongsheng-B40534; linux...@vger.kernel.org >>>> Subject: [PATCH V2 4/6] cpuidle/pseries: Move the pseries_idle >>>> backend driver to sysdev. >>>> >>>> Move pseries_idle backend driver code to arch/powerpc/sysdev so that >>>> the code can be used for a common driver for powernv and pseries. >>>> This removes a lot of code duplicacy. >>>> >>> Why not drivers/cpuidle/? >>> >>> I think it should be move to drivers/cpuidle. >> >> Please take a look at what the cpuidle under drivers has to provide. >> cpuidle has two parts to it. The front end and the back end. The front >> end constitutes the cpuidle governors, registering of arch specific >> cpuidle drivers, disabling and enabling of cpuidle feature. It is this >> front end code which is present under drivers/cpuidle. >> >> The arch specific cpuidle drivers which decide what needs to be done to >> enter a specific idle state chosen by the cpuidle governor is what >> constitutes the back end of cpuidle. This will not be in drivers/cpuidle >> but in an arch/ specific code. >> >> The cpuidle under drivers/cpuidle drives the idle power management, but >> the low level handling of the entry into idle states should be taken care >> of by the architecture. >> >> Your recent patch : >> cpuidle: add freescale e500 family porcessors idle support IMO should >> hook onto the backend cpuidle driver that this patchset provides. >> > Sorry, I don't think so, cpuidle framework has been already very common. > Here we just need to do state definition and handling. I wonder whether > we need this layer. > > If your handle is platform dependent, it should be in arch/platform. > > If it is only for some platforms and the operation of these platforms can be > multiplexed, Why cannot as a driver to put into driver/cpuidle? > > If it a general driver, I think we can put some common operating to > driver/cpuidle > and make the platform specific code to arch/powerpc/platform. > > This patch include front end and back end, not just back end. > > This patch include too many state of different platforms and handle function. > This state > and handle that should belong to itself platforms. Not a general way. If > Deepthi will do > a general powerpc cpuidle, I think, it's cannot just using the macro to > distinguish > platform. the front end code maybe move to driver/cpuidle(drvier register) > should be better, > make the Low Power State and what should be handle to > arch/powerpc/platform/**, because different > platforms have different state of low power consumption, and the processing > method. > The front end can provide some general methods to register into general > powerpc cpuidle driver.
As Daniel pointed out, with a call to cpuidle_register(), we can get the cpuidle_driver and cpuidle_device registered through the generic cpuidle framework. Hence we can get rid of the powerpc_idle_devices_init() routine. We can have the hotplug notifier in the generic cpuidle framework as well. The rest of the patchset however should be arch specific IMO. Regards Preeti U Murthy > > -dongsheng > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev > _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev