Re: [PATCH 4/4] drm/i915: Get rid of the _unchecked() runime pm stuff

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

On Tue, Feb 11, 2025 at 11:54:29AM +0200, Jani Nikula wrote:
> On Tue, 11 Feb 2025, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > Seem to me that intel_runtime_pm.c already handles the
> > CONFIG_DRM_I915_DEBUG_RUNTIME_PM=n case perfectly fine
> > internally, so I don't understand why it's being leaked into
> > all the callers as well. Get rid of all this the externally
> > visible _unchecked() stuff.
> 
> I think I've sent a similar patch in the past, and I think Imre
> explained the rationale was that passing the wakeref around for
> non-debug builds increases code size by 1k or something.

Yes, in non-debug builds the

intel_runtime_pm_put(rpm, wakeref) calls are converted to
intel_runtime_pm_put_unchecked(rpm),

and the

intel_display_power_put(display, domain, wakeref) calls are converted to
intel_display_power_put_unchecked(display, domain).

The rational was that these are called from many (184) places, thus
saving ~2.5kB in code.

> Yet this optimization makes the code harder to read.

Ok, agree with this one and I'm not sure if the optimization justifies
it. I think the same could be achieved simpler (only a wakeref pointer
passed to intel_display_power_put(), deducing both display and domain
from the wakeref), so on the patch:
Reviewed-by: Imre Deak <imre.deak@intel.com>

> I'm a bit divided on this one.
> 
> Cc: Imre
> 
> 
> BR,
> Jani.
> 
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  .../drm/i915/display/intel_display_power.c    | 24 ---------------
> >  .../drm/i915/display/intel_display_power.h    | 30 -------------------
> >  drivers/gpu/drm/i915/intel_gvt.c              |  3 --
> >  drivers/gpu/drm/i915/intel_runtime_pm.c       | 19 ------------
> >  drivers/gpu/drm/i915/intel_runtime_pm.h       |  9 ------
> >  5 files changed, 85 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
> > index d93f43d145a9..20296ab450bf 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_power.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display_power.c
> > @@ -809,7 +809,6 @@ intel_display_power_flush_work_sync(struct intel_display *display)
> >  	drm_WARN_ON(display->drm, power_domains->async_put_wakeref);
> >  }
> >  
> > -#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
> >  /**
> >   * intel_display_power_put - release a power domain reference
> >   * @display: display device instance
> > @@ -829,29 +828,6 @@ void intel_display_power_put(struct intel_display *display,
> >  	__intel_display_power_put(display, domain);
> >  	intel_runtime_pm_put(&dev_priv->runtime_pm, wakeref);
> >  }
> > -#else
> > -/**
> > - * intel_display_power_put_unchecked - release an unchecked power domain reference
> > - * @display: display device instance
> > - * @domain: power domain to reference
> > - *
> > - * This function drops the power domain reference obtained by
> > - * intel_display_power_get() and might power down the corresponding hardware
> > - * block right away if this is the last reference.
> > - *
> > - * This function is only for the power domain code's internal use to suppress wakeref
> > - * tracking when the corresponding debug kconfig option is disabled, should not
> > - * be used otherwise.
> > - */
> > -void intel_display_power_put_unchecked(struct intel_display *display,
> > -				       enum intel_display_power_domain domain)
> > -{
> > -	struct drm_i915_private *dev_priv = to_i915(display->drm);
> > -
> > -	__intel_display_power_put(display, domain);
> > -	intel_runtime_pm_put_unchecked(&dev_priv->runtime_pm);
> > -}
> > -#endif
> >  
> >  void
> >  intel_display_power_get_in_set(struct intel_display *display,
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_power.h b/drivers/gpu/drm/i915/display/intel_display_power.h
> > index a3a5c1be8bab..52b8a89b96eb 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_power.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display_power.h
> > @@ -195,7 +195,6 @@ void __intel_display_power_put_async(struct intel_display *display,
> >  				     intel_wakeref_t wakeref,
> >  				     int delay_ms);
> >  void intel_display_power_flush_work(struct intel_display *display);
> > -#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
> >  void intel_display_power_put(struct intel_display *display,
> >  			     enum intel_display_power_domain domain,
> >  			     intel_wakeref_t wakeref);
> > @@ -215,35 +214,6 @@ intel_display_power_put_async_delay(struct intel_display *display,
> >  {
> >  	__intel_display_power_put_async(display, domain, wakeref, delay_ms);
> >  }
> > -#else
> > -void intel_display_power_put_unchecked(struct intel_display *display,
> > -				       enum intel_display_power_domain domain);
> > -
> > -static inline void
> > -intel_display_power_put(struct intel_display *display,
> > -			enum intel_display_power_domain domain,
> > -			intel_wakeref_t wakeref)
> > -{
> > -	intel_display_power_put_unchecked(display, domain);
> > -}
> > -
> > -static inline void
> > -intel_display_power_put_async(struct intel_display *display,
> > -			      enum intel_display_power_domain domain,
> > -			      intel_wakeref_t wakeref)
> > -{
> > -	__intel_display_power_put_async(display, domain, INTEL_WAKEREF_DEF, -1);
> > -}
> > -
> > -static inline void
> > -intel_display_power_put_async_delay(struct intel_display *display,
> > -				    enum intel_display_power_domain domain,
> > -				    intel_wakeref_t wakeref,
> > -				    int delay_ms)
> > -{
> > -	__intel_display_power_put_async(display, domain, INTEL_WAKEREF_DEF, delay_ms);
> > -}
> > -#endif
> >  
> >  void
> >  intel_display_power_get_in_set(struct intel_display *display,
> > diff --git a/drivers/gpu/drm/i915/intel_gvt.c b/drivers/gpu/drm/i915/intel_gvt.c
> > index dae9dce7d1b3..164be5b8acb3 100644
> > --- a/drivers/gpu/drm/i915/intel_gvt.c
> > +++ b/drivers/gpu/drm/i915/intel_gvt.c
> > @@ -310,10 +310,7 @@ EXPORT_SYMBOL_NS_GPL(__intel_context_do_pin, "I915_GVT");
> >  EXPORT_SYMBOL_NS_GPL(__intel_context_do_unpin, "I915_GVT");
> >  EXPORT_SYMBOL_NS_GPL(intel_ring_begin, "I915_GVT");
> >  EXPORT_SYMBOL_NS_GPL(intel_runtime_pm_get, "I915_GVT");
> > -#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
> >  EXPORT_SYMBOL_NS_GPL(intel_runtime_pm_put, "I915_GVT");
> > -#endif
> > -EXPORT_SYMBOL_NS_GPL(intel_runtime_pm_put_unchecked, "I915_GVT");
> >  EXPORT_SYMBOL_NS_GPL(intel_uncore_forcewake_for_reg, "I915_GVT");
> >  EXPORT_SYMBOL_NS_GPL(intel_uncore_forcewake_get, "I915_GVT");
> >  EXPORT_SYMBOL_NS_GPL(intel_uncore_forcewake_put, "I915_GVT");
> > diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
> > index 8d9f4c410546..070bafb0a460 100644
> > --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> > @@ -322,24 +322,6 @@ intel_runtime_pm_put_raw(struct intel_runtime_pm *rpm, intel_wakeref_t wref)
> >  	__intel_runtime_pm_put(rpm, wref, false);
> >  }
> >  
> > -/**
> > - * intel_runtime_pm_put_unchecked - release an unchecked runtime pm reference
> > - * @rpm: the intel_runtime_pm structure
> > - *
> > - * This function drops the device-level runtime pm reference obtained by
> > - * intel_runtime_pm_get() and might power down the corresponding
> > - * hardware block right away if this is the last reference.
> > - *
> > - * This function exists only for historical reasons and should be avoided in
> > - * new code, as the correctness of its use cannot be checked. Always use
> > - * intel_runtime_pm_put() instead.
> > - */
> > -void intel_runtime_pm_put_unchecked(struct intel_runtime_pm *rpm)
> > -{
> > -	__intel_runtime_pm_put(rpm, INTEL_WAKEREF_DEF, true);
> > -}
> > -
> > -#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
> >  /**
> >   * intel_runtime_pm_put - release a runtime pm reference
> >   * @rpm: the intel_runtime_pm structure
> > @@ -353,7 +335,6 @@ void intel_runtime_pm_put(struct intel_runtime_pm *rpm, intel_wakeref_t wref)
> >  {
> >  	__intel_runtime_pm_put(rpm, wref, true);
> >  }
> > -#endif
> >  
> >  /**
> >   * intel_runtime_pm_enable - enable runtime pm
> > diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.h b/drivers/gpu/drm/i915/intel_runtime_pm.h
> > index 7428bd8fa67f..6eee55e3ff0b 100644
> > --- a/drivers/gpu/drm/i915/intel_runtime_pm.h
> > +++ b/drivers/gpu/drm/i915/intel_runtime_pm.h
> > @@ -204,16 +204,7 @@ intel_wakeref_t intel_runtime_pm_get_raw(struct intel_runtime_pm *rpm);
> >  	for ((wf) = intel_runtime_pm_get_if_active(rpm); (wf); \
> >  	     intel_runtime_pm_put((rpm), (wf)), (wf) = NULL)
> >  
> > -void intel_runtime_pm_put_unchecked(struct intel_runtime_pm *rpm);
> > -#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
> >  void intel_runtime_pm_put(struct intel_runtime_pm *rpm, intel_wakeref_t wref);
> > -#else
> > -static inline void
> > -intel_runtime_pm_put(struct intel_runtime_pm *rpm, intel_wakeref_t wref)
> > -{
> > -	intel_runtime_pm_put_unchecked(rpm);
> > -}
> > -#endif
> >  void intel_runtime_pm_put_raw(struct intel_runtime_pm *rpm, intel_wakeref_t wref);
> >  
> >  #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
> 
> -- 
> Jani Nikula, Intel