From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nishanth Menon <nm@ti.com>
Subject: Re: [PATCH 2/3] ARM: OMAP3+: PM: VP: check to ensure VP is idle
 before forceupdate
Date: Thu, 31 May 2012 18:37:01 -0500
Message-ID: <20120531233700.GB23870@horus>
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To: Kevin Hilman <khilman@ti.com>
Cc: Tony Lindgren <tony@atomide.com>, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Vinay Amancha <vinaykumar@ti.com>

On 16:23-20120531, Kevin Hilman wrote:
> Nishanth Menon <nm@ti.com> writes:
> 
> > Ideally in the flow of DVFS programming, VP should be in idle state
> > (since we disabled it) before entering forceupdate. Ensure that
> > this is the case. Not doing this could cause VP statemachine
> > to enter invalid states.
> >
> > Cc: Tony Lindgren <tony@atomide.com>
> > Cc: Kevin Hilman <khilman@ti.com>
> > Cc: linux-omap@vger.kernel.org
> > Cc: linux-arm-kernel@lists.infradead.org
> >
> > Signed-off-by: Vinay Amancha <vinaykumar@ti.com>
> > Signed-off-by: Nishanth Menon <nm@ti.com>
> > ---
> >  arch/arm/mach-omap2/vp.c |   12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> >
> > diff --git a/arch/arm/mach-omap2/vp.c b/arch/arm/mach-omap2/vp.c
> > index 925d869..985091b 100644
> > --- a/arch/arm/mach-omap2/vp.c
> > +++ b/arch/arm/mach-omap2/vp.c
> > @@ -123,6 +123,18 @@ int omap_vp_forceupdate_scale(struct voltagedomain *voltdm,
> >  	u8 target_vsel, current_vsel;
> >  	int ret, timeout = 0;
> >  
> > +/*
> 
> missing indent
oops. will fix
> 
> > +	 * Wait for VP idle Typical latency is <2us. Maximum latency is ~100us
> > +	 * This is an additional allowance to ensure we are in proper state
> > +	 * to enter into forceupdate state transition.
> > +	 */
> > +	omap_test_timeout((voltdm->read(vp->vstatus)),
> > +			  VP_IDLE_TIMEOUT, timeout);
> > +
> > +	if (timeout >= VP_IDLE_TIMEOUT)
> > +		pr_warning("%s: vdd_%s idle timedout forceupdate(v=%ld)\n",
> > +			   __func__, voltdm->name, target_volt);
> > +
> 
> Again, some clean failure and error recovery should be done here instead
> of just a print and bail.
thx - we should at least refuse to do forceupdate at this point.

-- 
Regards,
Nishanth Menon