Re: [PATCH v2 8/8] drm/i915: add a debugfs entry for power domain info

[Imre Deak <imre.deak@intel.com>]

On Fri, 2013-11-22 at 15:32 -0200, Paulo Zanoni wrote:
> 2013/11/14 Imre Deak <imre.deak@intel.com>:
> > Add a debugfs entry showing the use-count for all power domains of each
> > power well.
> >
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_debugfs.c | 69 +++++++++++++++++++++++++++++++++++++
> >  drivers/gpu/drm/i915/i915_drv.h     |  4 +++
> >  drivers/gpu/drm/i915/intel_pm.c     | 16 ++++++---
> >  3 files changed, 85 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> > index 6875b7a..a6555cd 100644
> > --- a/drivers/gpu/drm/i915/i915_debugfs.c
> > +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> > @@ -1844,6 +1844,74 @@ static int i915_pc8_status(struct seq_file *m, void *unused)
> >         return 0;
> >  }
> >
> > +static const char *power_domain_str(enum intel_display_power_domain domain)
> > +{
> > +#define PWRD(p)        { POWER_DOMAIN_ ## p, # p }
> > +       static struct {
> > +               enum intel_display_power_domain domain;
> > +               const char *name;
> > +       } table[] = {
> > +               PWRD(PIPE_A),
> > +               PWRD(PIPE_B),
> > +               PWRD(PIPE_C),
> > +               PWRD(PIPE_A_PANEL_FITTER),
> > +               PWRD(PIPE_B_PANEL_FITTER),
> > +               PWRD(PIPE_C_PANEL_FITTER),
> > +               PWRD(TRANSCODER_A),
> > +               PWRD(TRANSCODER_B),
> > +               PWRD(TRANSCODER_C),
> > +               PWRD(TRANSCODER_EDP),
> > +               PWRD(VGA),
> > +               PWRD(AUDIO),
> > +               PWRD(INIT),
> > +       };
> > +#undef PWRD
> > +       int i;
> > +
> > +       for (i = 0; i < ARRAY_SIZE(table); i++)
> > +               if (table[i].domain == domain)
> > +                       return table[i].name;
> 
> Why not just "return table[domain].name" instead of the 3 lines above?

In the first version I had the POWER_DOMAIN_* values redefined to be
bitmasks, where this wouldn't have worked. 

> Our driver has a few of these functions returning strings for enums
> and they usually just contain a "switch" statement on the enum,
> without using complicated macros. I tend to prefer the simple things.

I think this is mostly a matter of taste, having a switch table allows
for mistypings for example. But I don't mind rewriting it if that's a
more standard way in the driver.

> > +
> > +       WARN_ON(1);
> > +
> > +       return "?";
> > +}
> > +
> > +static int i915_power_domain_info(struct seq_file *m, void *unused)
> > +{
> > +       struct drm_info_node *node = (struct drm_info_node *) m->private;
> > +       struct drm_device *dev = node->minor->dev;
> > +       struct drm_i915_private *dev_priv = dev->dev_private;
> > +       struct i915_power_domains *power_domains = &dev_priv->power_domains;
> > +       int i;
> > +
> > +       mutex_lock(&power_domains->lock);
> > +
> > +       seq_printf(m, "%-25s %s\n", "Power well/domain", "Use count");
> > +       for (i = 0; i < power_domains->power_well_count; i++) {
> > +               struct i915_power_well *power_well;
> > +               enum intel_display_power_domain power_domain;
> > +
> > +               power_well = &power_domains->power_wells[i];
> > +               seq_printf(m, "%-25s %d\n", power_well->name,
> > +                          power_well->count);
> > +
> > +               for (power_domain = 0; power_domain < POWER_DOMAIN_NUM;
> > +                    power_domain++) {
> > +                       if (!(BIT(power_domain) & power_well->domains))
> > +                               continue;
> > +
> > +                       seq_printf(m, "  %-23s %d\n",
> > +                                  power_domain_str(power_domain),
> > +                                  power_well->domain_count[power_domain]);
> > +               }
> > +       }
> > +
> > +       mutex_unlock(&power_domains->lock);
> > +
> > +       return 0;
> > +}
> > +
> >  struct pipe_crc_info {
> >         const char *name;
> >         struct drm_device *dev;
> > @@ -3076,6 +3144,7 @@ static const struct drm_info_list i915_debugfs_list[] = {
> >         {"i915_edp_psr_status", i915_edp_psr_status, 0},
> >         {"i915_energy_uJ", i915_energy_uJ, 0},
> >         {"i915_pc8_status", i915_pc8_status, 0},
> > +       {"i915_power_domain_info", i915_power_domain_info, 0},
> >  };
> >  #define I915_DEBUGFS_ENTRIES ARRAY_SIZE(i915_debugfs_list)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > index 06f47bf..194e39f 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -950,6 +950,10 @@ struct i915_power_well {
> >         /* power well enable/disable usage count */
> >         int count;
> >         unsigned long domains;
> > +#if IS_ENABLED(CONFIG_DEBUG_FS)
> > +       /* usage count for each power domain in the domains mask */
> > +       int domain_count[POWER_DOMAIN_NUM];
> 
> Shouldn't we track this in struct power_domains, since when we get a
> domain we don't get it for a specific power well, but just "get the
> domain"? I think it makes more sense.

It belongs to the power well. For instance in theory we could have a
power domain that needs more than a single power well to be on.

> > +#endif
> >         void *data;
> >         void (*set)(struct drm_device *dev, struct i915_power_well *power_well,
> >                     bool enable);
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index d252453..99210c1 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -5726,17 +5726,25 @@ static void hsw_set_power_well(struct drm_device *dev,
> >  }
> >
> >  static void __intel_power_well_get(struct drm_device *dev,
> > -                                  struct i915_power_well *power_well)
> > +                                  struct i915_power_well *power_well,
> > +                                  enum intel_display_power_domain domain)
> >  {
> > +#if IS_ENABLED(CONFIG_DEBUG_FS)
> > +       power_well->domain_count[domain]++;
> > +#endif
> >         if (!power_well->count++ && power_well->set)
> >                 power_well->set(dev, power_well, true);
> >  }
> >
> >  static void __intel_power_well_put(struct drm_device *dev,
> > -                                  struct i915_power_well *power_well)
> > +                                  struct i915_power_well *power_well,
> > +                                  enum intel_display_power_domain domain)
> >  {
> >         WARN_ON(!power_well->count);
> >
> > +#if IS_ENABLED(CONFIG_DEBUG_FS)
> 
> WARN_ON(power_well->domain_count[domain] == 0);

Ok, will add this.

--Imre

> 
> > +       power_well->domain_count[domain]--;
> > +#endif
> >         if (!--power_well->count && power_well->set && i915_disable_power_well)
> >                 power_well->set(dev, power_well, false);
> >  }
> > @@ -5753,7 +5761,7 @@ void intel_display_power_get(struct drm_device *dev,
> >
> >         mutex_lock(&power_domains->lock);
> >         for_each_power_well(i, power_well, BIT(domain), power_domains)
> > -               __intel_power_well_get(dev, power_well);
> > +               __intel_power_well_get(dev, power_well, domain);
> >         mutex_unlock(&power_domains->lock);
> >  }
> >
> > @@ -5769,7 +5777,7 @@ void intel_display_power_put(struct drm_device *dev,
> >
> >         mutex_lock(&power_domains->lock);
> >         for_each_power_well_rev(i, power_well, BIT(domain), power_domains)
> > -               __intel_power_well_put(dev, power_well);
> > +               __intel_power_well_put(dev, power_well, domain);
> >         mutex_unlock(&power_domains->lock);
> >  }
> >
> > --
> > 1.8.4
> >
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> 
> 
>