> -----Original Message-----
> From: Paul Walmsley [mailto:p...@pwsan.com]
> Sent: Monday, April 05, 2010 4:44 PM
> To: Sripathy, Vishwanath
> Cc: linux-omap@vger.kernel.org
> Subject: RE: [PATCHV3 1/2] OMAP3: Set MPU and IVA bypass Clock Divider
>
> On Mon, 5 Apr 2010, Sripathy, Vishwanath wrote:
>
> > > -----Original Message-----
> > > From: Paul Walmsley [mailto:p...@pwsan.com]
> > >
> > > On Thu, 1 Apr 2010, Vishwanath BS wrote:
> > >
> > > > diff --git a/arch/arm/mach-omap2/clock3xxx_data.c b/arch/arm/mach-
> > > omap2/clock3xxx_data.c
> > > > index d5153b6..d8e57a6
> > > > --- a/arch/arm/mach-omap2/clock3xxx_data.c
> > > > +++ b/arch/arm/mach-omap2/clock3xxx_data.c
> > > > @@ -3597,5 +3601,13 @@ int __init omap3xxx_clk_init(void)
> > > > sdrc_ick_p = clk_get(NULL, "sdrc_ick");
> > > > arm_fck_p = clk_get(NULL, "arm_fck");
> > > >
> > > > + /* Set the bypass clock dividers for DPLL1 and DPLL2 */
> > > > + if (cpu_is_omap3630()) {
> > > > + clk_set_rate(&dpll1_fck, 400000000/2);
> > > > + clk_set_rate(&dpll2_fck, 400000000/2);
> > > > + } else {
> > > > + clk_set_rate(&dpll1_fck, 332000000/4);
> > > > + clk_set_rate(&dpll2_fck, 332000000/4);
> > > > + }
> > >
> > > This code is highly OPP-specific. Why is this code needed here?
> > > Shouldn't the code in resource34xx.c be sufficient?
> >
> > Code in resource34xx.c will be executed only when DVFS is executed.
> > However above code makes sure that initial values of Bypass clock
> > dividers are good. This will ensure that even if DVFS is disabled,
> > IVA/MPU are never overclocked when they enter bypass mode.
>
> My point is that you don't know how the bootloader has configured the
> system at the point when this code executes. You don't know what voltage
> level VDD1 and VDD2 are at; you don't know what state the clock tree is
> in. You only know this when you change OPPs. And the selection of the
> OPP at startup is use-case dependent.
>
May be I can move this code to init_opp?
> So as far as I can tell, this code shouldn't be there. If you want to do
> something like this, then you should add some generic way (e.g., a kernel
> command line parameter) to set the VDD1 and VDD2 OPPs at boot.
>
>
> - Paul
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