[PATCH 1/2] powerpc/85xx: add hardware automatically enter altivec idle state

Scott Wood scottwood at freescale.com
Sat Aug 17 02:50:53 EST 2013

On Fri, 2013-08-16 at 06:02 -0500, Kumar Gala wrote:
> On Aug 16, 2013, at 2:23 AM, Dongsheng Wang wrote:
> > From: Wang Dongsheng <dongsheng.wang at freescale.com>
> > 
> > Each core's AltiVec unit may be placed into a power savings mode
> > by turning off power to the unit. Core hardware will automatically
> > power down the AltiVec unit after no AltiVec instructions have
> > executed in N cycles. The AltiVec power-control is triggered by hardware.
> > 
> > Signed-off-by: Wang Dongsheng <dongsheng.wang at freescale.com>
> Why treat this as a idle HW governor vs just some one time setup at boot of the time delay?

It is being done as one-time setup, despite the function name.

Maybe it should be moved into __setup/restore_cpu_e6500 (BTW, we really
should refactor those to reduce duplication) with the timebase bit
number hardcoded rather than a time in us.

As for the PVR check, the upstream kernel doesn't need to care about
rev1, so knowing it's an e6500 is good enough.


More information about the Linuxppc-dev mailing list