Re: [PATCH] clk: Add tracepoints for hardware operations

[Mike Turquette <mturquette@linaro.org>]

Quoting Steven Rostedt (2015-02-02 08:00:33)
> On Fri, 30 Jan 2015 16:16:11 -0800
> Stephen Boyd <sboyd@codeaurora.org> wrote:
> 
> > It's useful to have tracepoints around operations that change the
> > hardware state so that we can debug clock hardware performance
> > and operations. Four basic types of events are supported: on/off
> > events for enable, disable, prepare, unprepare that only record
> > an event and a clock name, rate changing events for
> > clk_set_{min_,max_}rate{_range}(), phase changing events for
> > clk_set_phase() and parent changing events for clk_set_parent().
> > 
> > Cc: Steven Rostedt <rostedt@goodmis.org>
> 
> I don't see anything wrong with the implementation of the tracepoints.
> Now whether or not they are useful is up to the clk maintainer to
> decide.

Steven,

Thanks for the review. Stephen Boyd is now co-maintaining the framework
by the way.

Regards,
Mike

> 
> > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> > ---
> >  drivers/clk/clk.c          |  32 ++++++++
> >  include/trace/events/clk.h | 198 +++++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 230 insertions(+)
> >  create mode 100644 include/trace/events/clk.h
> > 
> 
> 
>   
> >  unlock_out:
> > @@ -861,9 +868,12 @@ static void clk_core_unprepare(struct clk_core *clk)
> >  
> >       WARN_ON(clk->enable_count > 0);
> >  
> > +     trace_clk_unprepare(clk);
> > +
> >       if (clk->ops->unprepare)
> >               clk->ops->unprepare(clk->hw);
> >  
> > +     trace_clk_unprepare_complete(clk);
> >       clk_core_unprepare(clk->parent);
> 
> I guess you do not care about the clk_core_unprepare time.
> 
> >  }
> >  
> > @@ -901,6 +911,8 @@ static int clk_core_prepare(struct clk_core *clk)
> >               if (ret)
> >                       return ret;
> >  
> > +             trace_clk_prepare(clk);
> > +
> >               if (clk->ops->prepare) {
> >                       ret = clk->ops->prepare(clk->hw);
> >                       if (ret) {
> > @@ -908,6 +920,8 @@ static int clk_core_prepare(struct clk_core *clk)
> >                               return ret;
> >                       }
> >               }
> > +
> > +             trace_clk_prepare_complete(clk);
> 
> I'm curious to why you do not put the tracepoint within the if
> statement, and only show the tracepoints if the clock prepare is
> actually called. Also, if you exit out with that return, will you tools
> be OK with seeing the clk_prepare but not the clk_prepare_complete?
> 
> 
> >       }
> >  
> >       clk->prepare_count++;
> > @@ -953,9 +967,13 @@ static void clk_core_disable(struct clk_core *clk)
> >       if (--clk->enable_count > 0)
> >               return;
> >  
> > +     trace_clk_disable(clk);
> > +
> >       if (clk->ops->disable)
> >               clk->ops->disable(clk->hw);
> >  
> > +     trace_clk_disable_complete(clk);
> > +
> >       clk_core_disable(clk->parent);
> >  }
> >  
> > @@ -1008,6 +1026,7 @@ static int clk_core_enable(struct clk_core *clk)
> >               if (ret)
> >                       return ret;
> >  
> > +             trace_clk_enable(clk);
> >               if (clk->ops->enable) {
> >                       ret = clk->ops->enable(clk->hw);
> >                       if (ret) {
> > @@ -1015,6 +1034,7 @@ static int clk_core_enable(struct clk_core *clk)
> >                               return ret;
> >                       }
> >               }
> > +             trace_clk_enable_complete(clk);
> 
> Same here.
> 
> -- Steve
> 
> >       }
> >  
> >       clk->enable_count++;
> > @@ -1383,6 +1403,8 @@ static struct clk_core *__clk_set_parent_before(struct clk_core *clk,
> >       unsigned long flags;
> >       struct clk_core *old_parent = clk->parent;
> >  
> > +     trace_clk_set_parent(clk, parent);
> > +
> >       /*
> >        * Migrate prepare state between parents and prevent race with
> >        * clk_enable().
> > @@ -1427,6 +1449,8 @@ static void __clk_set_parent_after(struct clk_core *core,
> >               clk_core_disable(old_parent);
> >               clk_core_unprepare(old_parent);
> >       }
> > +
> > +     trace_clk_set_parent_complete(core, parent);
> >  }
> >  
> >  static int __clk_set_parent(struct clk_core *clk, struct clk_core *parent,
> > @@ -1663,6 +1687,8 @@ static void clk_change_rate(struct clk_core *clk)
> >       else if (clk->parent)
> >               best_parent_rate = clk->parent->rate;
> >  
> > +     trace_clk_set_rate(clk, clk->new_rate);
> > +
> >       if (clk->new_parent && clk->new_parent != clk->parent) {
> >               old_parent = __clk_set_parent_before(clk, clk->new_parent);
> >  
> > @@ -1681,6 +1707,8 @@ static void clk_change_rate(struct clk_core *clk)
> >       if (!skip_set_rate && clk->ops->set_rate)
> >               clk->ops->set_rate(clk->hw, clk->new_rate, best_parent_rate);
> >  
> > +     trace_clk_set_rate_complete(clk, clk->new_rate);
> > +
> >       clk->rate = clk_recalc(clk, best_parent_rate);
> >  
> >       if (clk->notifier_count && old_rate != clk->rate)
> > @@ -2081,6 +2109,8 @@ int clk_set_phase(struct clk *clk, int degrees)
> >  
> >       clk_prepare_lock();
> >  
> > +     trace_clk_set_phase(clk->core, degrees);
> > +
> >       if (!clk->core->ops->set_phase)
> >               goto out_unlock;
> >  
> > @@ -2090,6 +2120,8 @@ int clk_set_phase(struct clk *clk, int degrees)
> >               clk->core->phase = degrees;
> >  
> >  out_unlock:
> > +     trace_clk_set_phase_complete(clk->core, degrees);
> > +
> >       clk_prepare_unlock();
> >  
> >  out:
>