[PATCH v2 06/15] powerpc/85xx: add support to JOG feature using cpufreq interface

[Zhao Chenhui]

On Mon, Apr 22, 2013 at 01:43:29AM +0200, Rafael J. Wysocki wrote:
> On Friday, April 19, 2013 07:00:57 PM Zhao Chenhui wrote:
> > ----- Forwarded message from Zhao Chenhui <chenhui.zhao at freescale.com> -----
> > 
> > Date: Fri, 19 Apr 2013 18:47:39 +0800
> > From: Zhao Chenhui <chenhui.zhao at freescale.com>
> > To: linuxppc-dev at lists.ozlabs.org
> > CC: linux-kernel at vger.kernel.org
> > Subject: [linuxppc-release] [PATCH v2 06/15] powerpc/85xx: add support to JOG feature using cpufreq interface
> > X-Mailer: git-send-email 1.7.3
> > 
> > From: chenhui zhao <chenhui.zhao at freescale.com>
> > 
> > Some 85xx silicons like MPC8536 and P1022 have a JOG feature, which provides
> > a dynamic mechanism to lower or raise the CPU core clock at runtime.
> > 
> > This patch adds the support to change CPU frequency using the standard
> > cpufreq interface. The ratio CORE to CCB can be 1:1(except MPC8536), 3:2,
> > 2:1, 5:2, 3:1, 7:2 and 4:1.
> > 
> > Two CPU cores on P1022 must not in the low power state during the frequency
> > transition. The driver uses a atomic counter to meet the requirement.
> > 
> > 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.
> >  * The driver doesn't support MPC8536 Rev 1.0 due to a JOG erratum.
> >    Subsequent revisions of MPC8536 have corrected the erratum.
> > 
> > Signed-off-by: Dave Liu <daveliu at freescale.com>
> > Signed-off-by: Li Yang <leoli at freescale.com>
> > Signed-off-by: Jerry Huang <Chang-Ming.Huang at freescale.com>
> > Signed-off-by: Zhao Chenhui <chenhui.zhao at freescale.com>
> > CC: Scott Wood <scottwood at freescale.com>
> 
> Well, I'd like someone from the PowerPC camp to comment on this before I take it.
> 
> Thanks,
> Rafael
> 

OK. Thanks.

-Chenhui