RE: [PATCHv1 1/1] omap3: pm: Delink opp layer and cpufreq

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> -----Original Message-----
> From: Nishanth Menon [mailto:menon.nishanth@xxxxxxxxx] 
> Sent: Monday, May 31, 2010 10:59 PM
> To: Premi, Sanjeev
> Cc: linux-omap@xxxxxxxxxxxxxxx
> Subject: Re: [PATCHv1 1/1] omap3: pm: Delink opp layer and cpufreq
> 
> On 05/31/2010 03:39 PM, Sanjeev Premi wrote:
> > The OPP layer was contained in the CONFIG_CPU_FREQ.
> > This patch removes this containment relation.
> >
> > Signed-off-by: Sanjeev Premi<premi@xxxxxx>
> > ---
> >   arch/arm/mach-omap2/Makefile          |    6 +-
> >   arch/arm/mach-omap2/board-omap3evm.c  |    2 +-

[snip]--[snip]

> you sure this is the only board file having "omap3-opp.h" ? 
> anyway.. the 
> need for board files to use opp_init is gone with my patch
> http://marc.info/?l=linux-omap&m=127507237109393&w=2
> so I wont harp on it, I would rather post a cleanup patch for 
> all board 
> files once the patch is in..(or mebbe kevin could drop the patch that 
> adds opp_init_table to board files ;) )..
> 

[sp] You didn't reead the 0/1 of the patch series, where I have clearly
mentioned that I will make changes to the other board specific files
once there rest of the changes are well discussed. There may be, possibly,
more changes in the board specific files and we can review them in the
context of this file and then same can be repeated for other board files.

> >   arch/arm/mach-omap2/cpufreq34xx.c     |  164 
> --------------------------------
> >   arch/arm/mach-omap2/omap3-opp.h       |   20 ----
> >   arch/arm/mach-omap2/opp34xx_data.c    |  166 
> +++++++++++++++++++++++++++++++++
> >   arch/arm/mach-omap2/pm34xx.c          |    1 -
> >   arch/arm/plat-omap/Makefile           |    7 +-
> >   arch/arm/plat-omap/cpu-omap.c         |   47 +++++++++
> >   arch/arm/plat-omap/include/plat/opp.h |   82 +---------------
> >   arch/arm/plat-omap/opp.c              |   46 ---------
> >   10 files changed, 225 insertions(+), 316 deletions(-)
> >   delete mode 100644 arch/arm/mach-omap2/cpufreq34xx.c
> >   delete mode 100644 arch/arm/mach-omap2/omap3-opp.h
> >   create mode 100644 arch/arm/mach-omap2/opp34xx_data.c
> >

[sp]
> finding it difficult to align with this change, you introduce 
> omap3_pm_init_opp_table later into plat/opp.h which defeats generic 
> nature of opp.h - as it was supposed to be used for other 
> omaps as well..

In that case the function omap3_pm_init_opp_table() can be made
generic by renaming to omap_pm_init_opp_table and can be implemented
for each omap family.

If opp table has to be implementyed for each family then why have
different funtion with family specific prefixes?

Also, what this headerf ile is/was doing? only defining the
function to return -EINVAL when CONFIG_CPU_FREQ is not selected;
which is not required. For OPP layer to be used this table needs
to be populated. Now, there is only one place this function is
used, so why do/should be need a header for the same.

[snip]--[snip]

> +obj-y				+= opp.o
> +obj-$(CONFIG_TWL4030_POWER)	+= opp_twl_tps.o
NAK. you just need TWL4030_CORE not power here. any reason to retain 
power? it has no dependency on power..

[sp] Isn't this purpose of this opp to TWL linkage is to define
the voltages in terms the PMIC connected; and later make sure
that correct voltages are set via the PMIC? This is very much related
to POWER. We could also do it on CORE; but I don't see this as a
big issue.

But TWL4030 has more feature beyond PMIC but this is not the case
with other simpler PMICs and I wanted to use CONFIG option that
can be easier for someone else make the port easy to spot as a necessary
change.

[snip]--[snip]

> > +	freq_table[i].index = i;
> > +	freq_table[i].frequency = CPUFREQ_TABLE_END;
> > +
> > +	*table =&freq_table[0];
> > +}
> > +#endif
> > +
> errrr.... why? it used to be here and was moved to opp.c - see
> http://git.kernel.org/?p=linux/kernel/git/khilman/linux-omap-p
m.git;a=commit;h=9a6b00f70e9f4bce30ad4f8fab41a24bd3706dbd
> you are essentially reverting that patch!

[sp] May be I am reverting the patch, but I don't see this function
     being used anywhere else. Most of the other cpufreq related
     initialization is happening at this place.

     Only the function omap_cpu_init() calls this function and it
     is in the same file.

     It also helps in need of an additional header; which seem
     to make "de-linking" more complex - in terms of #ifdefs.

[snip]--[snip]

> 
> > +/**
> > + * omap3_pm_init_opp_table() - Initialize the OPP table 
> for OMAP3 devices.
> > + *
> > + * Initializes the OPP table for the current OMAP3 device.
> > + */
> > +int __init omap3_pm_init_opp_table(void);
> NAK. opp. is meant to be used by omap2, OMAP4 etc..
> when you removed from omap3-opp.h, it kinda needed you to 
> have it here, 
> which breaks the generic nature of this header.

[sp] See my comment earlier. The function for init-ing the OPP
     table can be made generic. Then (after rename) this is a
     generic function itself.

     Rather than making sweelping changes, I am only delinking
     the OPP layer and CPU freq. These changes can be done
     separately.

> 
> >
> > -#endif		/* CONFIG_CPU_FREQ */
> >   #endif		/* __ASM_ARM_OMAP_OPP_H */
> > diff --git a/arch/arm/plat-omap/opp.c b/arch/arm/plat-omap/opp.c
> > index 13da451..3ed3ec1 100644
> > --- a/arch/arm/plat-omap/opp.c
> > +++ b/arch/arm/plat-omap/opp.c
> > @@ -351,49 +351,3 @@ int opp_disable(struct omap_opp *opp)
> >   	opp->enabled = false;
> >   	return 0;
> >   }
> > -
> > -/* XXX document */
> > -void opp_init_cpufreq_table(enum opp_t opp_type,
> > -			    struct cpufreq_frequency_table **table)
> > -{
> > -	int i = 0, j;
> > -	int opp_num;
> > -	struct cpufreq_frequency_table *freq_table;
> > -	struct omap_opp *opp;
> > -
> > -	if (opp_type>= OPP_TYPES_MAX) {
> > -		pr_warning("%s: failed to initialize frequency"
> > -				"table\n", __func__);
> > -		return;
> > -	}
> > -
> > -	opp_num = opp_get_opp_count(opp_type);
> > -	if (opp_num<  0) {
> > -		pr_err("%s: no opp table?\n", __func__);
> > -		return;
> > -	}
> > -
> > -	freq_table = kmalloc(sizeof(struct cpufreq_frequency_table) *
> > -			     (opp_num + 1), GFP_ATOMIC);
> > -	if (!freq_table) {
> > -		pr_warning("%s: failed to allocate frequency"
> > -				"table\n", __func__);
> > -		return;
> > -	}
> > -
> > -	opp = _opp_list[opp_type];
> > -	opp += opp_num;
> > -	for (j = opp_num; j>= 0; j--) {
> > -		if (opp->enabled) {
> > -			freq_table[i].index = i;
> > -			freq_table[i].frequency = opp->rate / 1000;
> > -			i++;
> > -		}
> > -		opp--;
> > -	}
> > -
> > -	freq_table[i].index = i;
> > -	freq_table[i].frequency = CPUFREQ_TABLE_END;
> > -
> > -	*table =&freq_table[0];
> > -}
> not sure why you removed this..
> 

[sp] It isn't removed but simply moved to the only file in the code where it
     is being used... along with rest of the code related to CPU_FREQ.

The way I see, the OPP layer has been mixed with CPUFREQ usage in the
cureent code; but if you look at OPP layer as as "real" layer then the
CPUFREQ implementation should be the "client" to this later and use its
services - not get 'mingled' into the layer itself. If you go by this
reasoning, this init function belong outside the OPP layer.

Best regards,
Sanjeev--
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