RE: [PATCH 1/6] omap4: powerdomain: Add supported INACTIVE power state

[Santosh Shilimkar <santosh.shilimkar@ti.com>]

> -----Original Message-----
> From: Paul Walmsley [mailto:paul@pwsan.com]
> Sent: Thursday, February 03, 2011 3:11 AM
> To: Santosh Shilimkar
> Cc: linux-omap@vger.kernel.org; Kevin Hilman; Benoit Cousson;
> Rajendra Nayak; linux-arm-kernel@lists.infradead.org
> Subject: RE: [PATCH 1/6] omap4: powerdomain: Add supported INACTIVE
> power state
>
> On Tue, 1 Feb 2011, Santosh Shilimkar wrote:
>
> > > -----Original Message-----
> > > From: Paul Walmsley [mailto:paul@pwsan.com]
> > > Sent: Tuesday, February 01, 2011 4:44 AM
> > >
> > > What does the hardware do when the powerdomain is programmed to
> > > INACTIVE?
> > > Does it actually force the clockdomains idle?
> >
> > No. It doesn't force it. The power domain to hit INACTIVE, the
> > clockdomain within the power domain needs to idle and it is
> > still a prerequisite. With INACTIVE being programmed, we could
> > issue a sleep transition.
> >
> > PD_ON:
> > No power transition, only clocks are gated. Power domain stays ON.
> >
> > PD_INA:
> > Power domain transitions to INACTIVE state. All logic and
> > memory stay powered. This state allows for a voltage
> > sleep transition.
>
> Okay.  So programming an OMAP4 powerdomain to INACTIVE is equivalent
> to
> programming an OMAP3 powerdomain to ON with the
> PRM_VOLTCTRL.AUTO_SLEEP
> bit to 1?
>
> Are there any other dependencies with the
> PRM_VOLTCTRL_AUTO_CTRL_VDD*
> registers, e.g., does the appropriate VDD bitfield there need to be
> set to
> 0x1 also to allow the sleep transition to occur?
>
If we plan to do sleep transions, then DEVICE PRM needs to be
programmed for voltage level and the control bit enable.

Regards,
Santosh