Re: [Intel-gfx] [PATCH v2 06/20] drm/i915: Polish some dbuf debugs

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Mar 04, 2020 at 04:29:47PM +0000, Lisovskiy, Stanislav wrote:
> On Tue, 2020-02-25 at 19:11 +0200, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Polish some of the dbuf code to give more meaningful debug
> > messages and whatnot. Also we can switch over to the per-device
> > debugs/warns at the same time.
> > 
> > Cc: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  .../drm/i915/display/intel_display_power.c    | 40 +++++++++------
> > ----
> >  1 file changed, 19 insertions(+), 21 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c
> > b/drivers/gpu/drm/i915/display/intel_display_power.c
> > index 6e25a1317161..e81e561e8ac0 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_power.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display_power.c
> > @@ -4433,11 +4433,12 @@ static void
> > intel_power_domains_sync_hw(struct drm_i915_private *dev_priv)
> >  	mutex_unlock(&power_domains->lock);
> >  }
> >  
> > -static inline
> > -bool intel_dbuf_slice_set(struct drm_i915_private *dev_priv,
> > -			  i915_reg_t reg, bool enable)
> > +static void intel_dbuf_slice_set(struct drm_i915_private *dev_priv,
> > +				 enum dbuf_slice slice, bool enable)
> >  {
> > -	u32 val, status;
> > +	i915_reg_t reg = DBUF_CTL_S(slice);
> > +	bool state;
> > +	u32 val;
> >  
> >  	val = intel_de_read(dev_priv, reg);
> >  	val = enable ? (val | DBUF_POWER_REQUEST) : (val &
> > ~DBUF_POWER_REQUEST);
> > @@ -4445,13 +4446,10 @@ bool intel_dbuf_slice_set(struct
> > drm_i915_private *dev_priv,
> >  	intel_de_posting_read(dev_priv, reg);
> >  	udelay(10);
> >  
> > -	status = intel_de_read(dev_priv, reg) & DBUF_POWER_STATE;
> > -	if ((enable && !status) || (!enable && status)) {
> > -		drm_err(&dev_priv->drm, "DBus power %s timeout!\n",
> > -			enable ? "enable" : "disable");
> > -		return false;
> > -	}
> > -	return true;
> > +	state = intel_de_read(dev_priv, reg) & DBUF_POWER_STATE;
> > +	drm_WARN(&dev_priv->drm, enable != state,
> > +		 "DBuf slice %d power %s timeout!\n",
> > +		 slice, enable ? "enable" : "disable");
> >  }
> >  
> >  static void gen9_dbuf_enable(struct drm_i915_private *dev_priv)
> > @@ -4467,14 +4465,16 @@ static void gen9_dbuf_disable(struct
> > drm_i915_private *dev_priv)
> >  void icl_dbuf_slices_update(struct drm_i915_private *dev_priv,
> >  			    u8 req_slices)
> >  {
> > -	int i;
> > -	int max_slices = INTEL_INFO(dev_priv)-
> > >num_supported_dbuf_slices;
> > +	int num_slices = INTEL_INFO(dev_priv)-
> > >num_supported_dbuf_slices;
> >  	struct i915_power_domains *power_domains = &dev_priv-
> > >power_domains;
> > +	enum dbuf_slice slice;
> >  
> > -	drm_WARN(&dev_priv->drm, hweight8(req_slices) > max_slices,
> > -		 "Invalid number of dbuf slices requested\n");
> > +	drm_WARN(&dev_priv->drm, req_slices & ~(BIT(num_slices) - 1),
> > +		 "Invalid set of dbuf slices (0x%x) requested (num dbuf
> > slices %d)\n",
> > +		 req_slices, num_slices);
> >  
> > -	DRM_DEBUG_KMS("Updating dbuf slices to 0x%x\n", req_slices);
> > +	drm_dbg_kms(&dev_priv->drm,
> > +		    "Updating dbuf slices to 0x%x\n", req_slices);
> >  
> >  	/*
> >  	 * Might be running this in parallel to
> > gen9_dc_off_power_well_enable
> > @@ -4485,11 +4485,9 @@ void icl_dbuf_slices_update(struct
> > drm_i915_private *dev_priv,
> >  	 */
> >  	mutex_lock(&power_domains->lock);
> >  
> > -	for (i = 0; i < max_slices; i++) {
> > -		intel_dbuf_slice_set(dev_priv,
> > -				     DBUF_CTL_S(i),
> > -				     (req_slices & BIT(i)) != 0);
> > -	}
> > +	for (slice = DBUF_S1; slice < num_slices; slice++)
> > +		intel_dbuf_slice_set(dev_priv, slice,
> > +				     req_slices & BIT(slice));
> 
> Would be cool to completely get rid of any magic numbers or
> definitions, 0 in a sense is more universal here than DBUF_S1.
> 
> If we are counting slices as numbers it seems logical that we 
> iterate [0..num_slices) range. If you want to name the first slice
> explicitly then it probably has to be something like iterator
> logic, i.e for (slice = FIRST_SLICE; slice != LAST_SLICE; slice++).
> 
> But trying to name it at the same time with comparing to total _amount_
> looks a bit confusing.

This is the standard pattern used all over the driver.

-- 
Ville Syrjälä
Intel
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