Messages in this thread | | | Date | Wed, 6 Jun 2012 18:19:03 +0800 | From | Zhao Chenhui <> | Subject | Re: [PATCH v5 5/5] powerpc/85xx: add support to JOG feature using cpufreq interface |
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On Tue, Jun 05, 2012 at 10:58:41AM -0500, Scott Wood wrote: > On 06/05/2012 05:59 AM, Zhao Chenhui wrote: > > On Fri, Jun 01, 2012 at 06:30:55PM -0500, Scott Wood wrote: > >> On 05/11/2012 06:53 AM, Zhao Chenhui wrote: > >>> The jog mode frequency transition process on the MPC8536 is similar to > >>> the deep sleep process. The driver need save the CPU state and restore > >>> it after CPU warm reset. > >>> > >>> Note: > >>> * The I/O peripherals such as PCIe and eTSEC may lose packets during > >>> the jog mode frequency transition. > >> > >> That might be acceptable for eTSEC, but it is not acceptable to lose > >> anything on PCIe. Especially not if you're going to make this "default y". > > > > It is a hardware limitation. > > Then make sure jog isn't used if PCIe is used. > > Maybe you could do something with the suspend infrastructure, but this > is sufficiently heavyweight that transitions should be manually > requested, not triggered by the automatic cpufreq governor. > > Does this apply to p1022, or just mpc8536?
Both of them.
> > > Peripherals in the platform will not be operating > > during the jog mode frequency transition process. > > What ensures this? > > -Scott
Hardware ensures it without software intervention.
-Chenhui
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