RE: Question on OPP table handling

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> -----Original Message-----
> From: Premi, Sanjeev
> Sent: Tuesday, October 06, 2009 2:14 PM
> To: Shilimkar, Santosh; Menon, Nishanth; linux-omap@xxxxxxxxxxxxxxx
> Cc: Kevin H
> Subject: RE: Question on OPP table handling
> 
> 
> > -----Original Message-----
> > From: Shilimkar, Santosh
> > Sent: Tuesday, October 06, 2009 1:36 PM
> > To: Menon, Nishanth; linux-omap@xxxxxxxxxxxxxxx
> > Cc: Premi, Sanjeev; Kevin H
> > Subject: RE: Question on OPP table handling
> >
> > > -----Original Message-----
> > > From: linux-omap-owner@xxxxxxxxxxxxxxx [mailto:linux-omap-
> > > owner@xxxxxxxxxxxxxxx] On Behalf Of Nishanth Menon
> > > Sent: Monday, October 05, 2009 10:49 PM
> > > To: linux-omap@xxxxxxxxxxxxxxx
> > > Cc: Premi, Sanjeev; Kevin H
> > > Subject: Re: Question on OPP table handling
> > >
> > > Kevin Hilman had written, on 10/05/2009 11:56 AM, the following:
> > > > "Premi, Sanjeev" <premi@xxxxxx> writes:
> > > >
> > > >>> -----Original Message-----
> > > >>> From: Nishanth Menon [mailto:menon.nishanth@xxxxxxxxx]
> > > >>> Sent: Saturday, October 03, 2009 8:35 PM
> > > >>> To: Premi, Sanjeev
> > > >>> Cc: linux-omap@xxxxxxxxxxxxxxx
> > > >>> Subject: Question on OPP table handling
> > > >>>
> > > >>> Sanjeev Premi said the following on 10/01/2009 01:03 PM:
> > > >>>> +struct omap_opp omap3_mpu_rate_table[] = {
> > > >>>> +	{0, 0, 0},
> > > >>>> +	/*OPP1*/
> > > >>>> +	{S125M, VDD1_OPP1, 0x1E},
> > > >>>> +	/*OPP2*/
> > > >>>> +	{S250M, VDD1_OPP2, 0x26},
> > > >>>> +	/*OPP3*/
> > > >>>> +	{S500M, VDD1_OPP3, 0x30},
> > > >>>> +	/*OPP4*/
> > > >>>> +	{S550M, VDD1_OPP4, 0x36},
> > > >>>> +	/*OPP5*/
> > > >>>> +	{S600M, VDD1_OPP5, 0x3C},
> > > >>>> +};
> > > >>>>
> > > >>> For those involved,
> > > >>> if we wanted to convert omap3_mpu_table[] into
> > > >>> *omap3_mpu_table so that
> > > >>> we dynamically initialize it based on cpu type - what
> > would be the
> > > >>> recommendations?
> > > >> Nishanth,
> > > >>
> > > >> Good idea!
> > > >>
> > > >> As a table, previous patch enables it (not as intent, but due to
> > > syntax):
> > > >>
> > > >>   >  +/* struct omap_opp_table - View OPP table as an object
> > > >>   > + * @min: Minimum OPP id
> > > >>   > + * @max: Maximim OPP id
> > > >>   > + * @opps: Pointer to array defining the OPPs.
> > > >>   > + *
> > > >>   > + * An OPP table has varied length. Knowing minimum
> > and maximum
> > > >>   > + * OPP ids allow easy traversal.
> > > >>   > + */
> > > >>   > +struct omap_opp_table {
> > > >>   > +       u8      min;
> > > >>   > +       u8      max;
> > > >>   > +       struct omap_opp* opps;
> > > >>   > +};
> > > >>
> > > >> But now, I think it would be good to have an API that can fill an
> > > opp_table:
> > > >>
> > > >> int add_opp_definition(u8 id, u32 freq, u16 vsel);
> > > >>
> > > >> ...and, if an array is preferred, length can be set as:
> > > >> int set_opp_table_length (u8 max);
> > > >
> > > > I'm all for dynamic OPP setting, but not as an array.  A
> > list should
> > > > probably be used.
> > >
> > > Won't a list implementation cause more than necessary
> > overhead? I agree
> > > that something like set_opp_table_length probably might be
> > redundant in
> > > that case.
> > >
> > >
> > > >> If I were to extend the discussion from other thread on
> > toggling the
> > > valid OPPs
> > > >> based on "enable_off_mode", these could be handy.
> > > >>
> > > >> int set_opp_valid(bool flag);
> > > >> bool is_opp_valid(void);
> > > >>
> > > >
> > > > Yes, we need a concept of a valid OPP, not just for OFF
> > mode, but for
> > > > OSWR and possibly for a full constraint framework as well.
> > > Ack.
> > Even though above approach is possibly better a simple fix
> > could be just adding a flag in the structure (OPP
> > valid/invalid) and populating this flag run time using CPU type.
> >
> 
> [sp] This is exactly in the original patch.
OK

Regards,
Santosh

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