Re: [PATCH v4] drm/i915/icl: Fix clockgating issue when using scalers

["Sripada, Radhakrishna" <radhakrishna.sripada@intel.com>]

On Fri, 2019-03-29 at 20:39 +0200, Ville Syrjälä wrote:
> On Thu, Mar 28, 2019 at 10:35:19AM -0700, Radhakrishna Sripada wrote:
> > Fixes the clock-gating issue when pipe scaling is enabled.
> > (Lineage #2006604312)
> > 
> > V2: Fix typo in headline(Chris)
> >     Handle the non double buffered nature of the register(Ville)
> > V3: Fix checkpatch warning. BAT failure for V2 on gen3 looks
> > unrelated.
> > V4: Split the icl and skl wa's(Ville)
> > 
> > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
> > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > Cc: Aditya Swarup <aditya.swarup@intel.com>
> > Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com
> > >
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 48 ++++++++++++++++++++--
> > ------
> >  1 file changed, 34 insertions(+), 14 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_display.c
> > b/drivers/gpu/drm/i915/intel_display.c
> > index 8576a7f799f2..c3ca9cfd36fe 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -466,6 +466,7 @@ static const struct intel_limit
> > intel_limits_bxt = {
> >  	.p2 = { .p2_slow = 1, .p2_fast = 20 },
> >  };
> >  
> > +/* WA Display #0827: Gen9:all */
> >  static void
> >  skl_wa_clkgate(struct drm_i915_private *dev_priv, int pipe, bool
> > enable)
> >  {
> > @@ -478,6 +479,17 @@ skl_wa_clkgate(struct drm_i915_private
> > *dev_priv, int pipe, bool enable)
> >  			   ~(DUPS1_GATING_DIS | DUPS2_GATING_DIS));
> >  }
> >  
> > +/* Wa_2006604312:icl */
> > +static void
> > +icl_wa_clkgate(struct drm_i915_private *dev_priv, int pipe, bool
> > enable)
> 
> These functions names (including the skl one) are rather too generic
> and don't describe which clock gating we're disabling. But fixing
> that is probably material for another patch.
Sure let me spin out another patch for this.
> 
> > +{
> > +	if (enable)
> > +		I915_WRITE(CLKGATE_DIS_PSL(pipe), DPFR_GATING_DIS);
> > +	else
> > +		I915_WRITE(CLKGATE_DIS_PSL(pipe),
> > +			   I915_READ(CLKGATE_DIS_PSL(pipe)) &
> > ~DPFR_GATING_DIS);
> 
> No RMW for enable but RMW for disable? Seems rather inconsistent.
Sure looks inconsistent. Let me fix it next rev.
> 
> > +}
> > +
> >  static bool
> >  needs_modeset(const struct drm_crtc_state *state)
> >  {
> > @@ -5481,14 +5493,18 @@ static bool
> > hsw_post_update_enable_ips(const struct intel_crtc_state
> > *old_crtc_s
> >  	return !old_crtc_state->ips_enabled;
> >  }
> >  
> > -static bool needs_nv12_wa(struct drm_i915_private *dev_priv,
> > -			  const struct intel_crtc_state *crtc_state)
> > +static bool skl_needs_clk_wa(struct drm_i915_private *dev_priv,
> > +			     const struct intel_crtc_state *crtc_state)
> 
> Still mixing our workarounds more than I'd like. I suggest keeping
> the two entirely separate.
Sure let me separate it completely. Avoids duplicating checks as well.

Thanks,
Radhakrishna(RK) Sripada
> 
> >  {
> > -	if (!crtc_state->nv12_planes)
> > -		return false;
> > -
> >  	/* WA Display #0827: Gen9:all */
> > -	if (IS_GEN(dev_priv, 9) && !IS_GEMINILAKE(dev_priv))
> > +	if (!!crtc_state->nv12_planes && IS_GEN(dev_priv, 9) &&
> > +	    !IS_GEMINILAKE(dev_priv))
> > +		return true;
> > +
> > +	/*
> > +	 * Wa_2006604312:icl
> > +	 */
> > +	if (IS_ICELAKE(dev_priv) && crtc_state->pch_pfit.enabled)
> >  		return true;
> >  
> >  	return false;
> > @@ -5527,10 +5543,12 @@ static void intel_post_plane_update(struct
> > intel_crtc_state *old_crtc_state)
> >  			intel_post_enable_primary(&crtc->base,
> > pipe_config);
> >  	}
> >  
> > -	/* Display WA 827 */
> > -	if (needs_nv12_wa(dev_priv, old_crtc_state) &&
> > -	    !needs_nv12_wa(dev_priv, pipe_config)) {
> > -		skl_wa_clkgate(dev_priv, crtc->pipe, false);
> > +	if (skl_needs_clk_wa(dev_priv, old_crtc_state) &&
> > +	    !skl_needs_clk_wa(dev_priv, pipe_config)) {
> > +		if (IS_ICELAKE(dev_priv))
> > +			icl_wa_clkgate(dev_priv, crtc->pipe, false);
> > +		else
> > +			skl_wa_clkgate(dev_priv, crtc->pipe, false);
> >  	}
> >  }
> >  
> > @@ -5566,10 +5584,12 @@ static void intel_pre_plane_update(struct
> > intel_crtc_state *old_crtc_state,
> >  			intel_set_cpu_fifo_underrun_reporting(dev_priv,
> > crtc->pipe, false);
> >  	}
> >  
> > -	/* Display WA 827 */
> > -	if (!needs_nv12_wa(dev_priv, old_crtc_state) &&
> > -	    needs_nv12_wa(dev_priv, pipe_config)) {
> > -		skl_wa_clkgate(dev_priv, crtc->pipe, true);
> > +	if (!skl_needs_clk_wa(dev_priv, old_crtc_state) &&
> > +	    skl_needs_clk_wa(dev_priv, pipe_config)) {
> > +		if (IS_ICELAKE(dev_priv))
> > +			icl_wa_clkgate(dev_priv, crtc->pipe, true);
> > +		else
> > +			skl_wa_clkgate(dev_priv, crtc->pipe, true);
> >  	}
> >  
> >  	/*
> > -- 
> > 2.20.0.rc2.7.g965798d1f299
> 
> 
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