RE: [PATCH 1/3] PM / OPP: Add support for descending order for cpufreq table

[Jonghwan Choi]

Hi. Viresh Kumar
Your reply is so fast like Usain Bolt.

> So, create three flags:
> OPP_TABLE_ORDER_ASCENDING              0
> OPP_TABLE_ORDER_DESCENDING            1
> OPP_TABLE_ORDER_ORIGINAL                  2 (And use this for your case.)

-> Actually, I want to use OPP_TABLE_ORDER_DESCENDING.(Not
OPP_TABLE_ORDER_ORIGINAL.)
I think that it is enough to support both descending and ascending ordering
only.
The meaning of "ORIGIANL" Amit, said, when he(and I) writes a frequency in
dts file with ordering(Ascending or Descending). He(and I) want the
frequency to be register according to ordering.(Ascending or Descending).

I concerned that if we use ORIGINAL ordering, opp_find_freq_ceil/foor can be
broken.
(example, 1GH - 500MH - 800MHz - 200MHz - 600MHz)

Thanks~

Best Regars

> -----Original Message-----
> From: viresh.linux@xxxxxxxxx [mailto:viresh.linux@xxxxxxxxx] On Behalf Of
> Viresh Kumar
> Sent: Wednesday, April 30, 2014 5:25 PM
> To: Jonghwan Choi; Linux PM list
> Cc: open list; Rafael J. Wysocki; Len Brown; Amit Daniel Kachhap
> Subject: Re: [PATCH 1/3] PM / OPP: Add support for descending order for
> cpufreq table
> 
> Hi,
> 
> This isn't a very big patchset and this patch is very much required to
> understand other patches and so please cc all people from other list here
> as well..
> 
> On Wed, Apr 30, 2014 at 11:58 AM, Jonghwan Choi <jhbird.choi@xxxxxxxxxxx>
> wrote:
> > In the frequency table dts file, the frequencies are arranged in
> 
> Improve your logs a bit. Which dts file are you talking about here ?
> How would anybody know that you are talking about exynos here?
> 
> Also, you shouldn't mention that here, just tell the kind of requirement
> platforms may have. i.e. people may want to keep the opp list in the same
> order in which it came from DT.
> 
> > descending order which maps 1 to 1 with other frequency parameter to
> > be calculated and programmed in some registers.
> > But the OPP library works by generating the frequencies in ascending
> > order which breaks the above logic.
> > So added OPP_TABLE_ORDER_DESCEND flag to consider descending order.
> 
> So, create three flags:
> OPP_TABLE_ORDER_ASCENDING              0
> OPP_TABLE_ORDER_DESCENDING            1
> OPP_TABLE_ORDER_ORIGINAL                  2 (And use this for your case.)
> 
> > Cc: Amit Daniel Kachhap <amit.daniel@xxxxxxxxxxx>
> > Signed-off-by: Jonghwan Choi <jhbird.choi@xxxxxxxxxxx>
> > ---
> >  drivers/base/power/opp.c |   17 ++++++++++++++++-
> >  include/linux/pm_opp.h   |    7 +++++--
> >  2 files changed, 21 insertions(+), 3 deletions(-)
> 
> You are changing prototype of a function and so all other files which are
> using this routine will break after this patch and we can't afford it as
> we want git bisect to work properly.
> 
> So, fix all platforms here in this patch only, i.e. part of 2/3 and
> complete 3/3 should have been merged into this one.
> 
> > diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c index
> > 2553867..ec7d553 100644
> > --- a/drivers/base/power/opp.c
> > +++ b/drivers/base/power/opp.c
> > @@ -18,6 +18,7 @@
> >  #include <linux/cpufreq.h>
> >  #include <linux/device.h>
> >  #include <linux/list.h>
> > +#include <linux/list_sort.h>
> >  #include <linux/rculist.h>
> >  #include <linux/rcupdate.h>
> >  #include <linux/pm_opp.h>
> > @@ -597,10 +598,21 @@ int dev_pm_opp_disable(struct device *dev,
> > unsigned long freq)  EXPORT_SYMBOL_GPL(dev_pm_opp_disable);
> >
> >  #ifdef CONFIG_CPU_FREQ
> > +
> > +static int opp_descend_cmp(void *priv, struct list_head *a,
> > +                                        struct list_head *b) {
> > +        struct dev_pm_opp *ra = list_entry(a, struct dev_pm_opp, node);
> > +        struct dev_pm_opp *rb = list_entry(b, struct dev_pm_opp,
> > +node);
> > +
> > +        return rb->rate - ra->rate;
> > +}
> > +
> >  /**
> >   * dev_pm_opp_init_cpufreq_table() - create a cpufreq table for a
> device
> >   * @dev:       device for which we do this operation
> >   * @table:     Cpufreq table returned back to caller
> > + * @flags:     OPP_TABLE_ORDER_DESCEND or zero
> >   *
> >   * Generate a cpufreq table for a provided device- this assumes that
> the
> >   * opp list is already initialized and ready for usage.
> > @@ -622,7 +634,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_disable);
> >   * or in contexts where mutex locking cannot be used.
> >   */
> >  int dev_pm_opp_init_cpufreq_table(struct device *dev,
> > -                           struct cpufreq_frequency_table **table)
> > +               struct cpufreq_frequency_table **table, unsigned char
> > + flags)
> 
> You are targeting the wrong routine. Fix of_init_opp_table() instead and
> things would work automatically then..
> 
> And please don't change prototype of dev_pm_opp_add() for now and just
> define __dev_pm_opp_add() which will be called from
> dev_pm_opp_add() and of_init_opp_table() with 'int order' parameter.

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