Re: [PATCH v6] drm/i915/icl: Fix clockgating issue when using scalers

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

On Fri, Apr 05, 2019 at 02:14:37PM -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)
> V5: Split the checks for icl and skl(Ville)
> V6: Correct the flipped checks in intel_pre_plane_update(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 | 39 ++++++++++++++++++++++++----
>  1 file changed, 34 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index cf6046390eeb..ab820cad990d 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_827(struct drm_i915_private *dev_priv, int pipe, bool enable)
>  {
> @@ -479,6 +480,18 @@ skl_wa_827(struct drm_i915_private *dev_priv, int pipe, bool enable)
>  			   ~(DUPS1_GATING_DIS | DUPS2_GATING_DIS));
>  }
>  
> +/* Wa_2006604312:icl */
> +static void
> +icl_wa_scalerclkgating(struct drm_i915_private *dev_priv, int pipe, bool enable)

enum pipe please

> +{
> +	if (enable)
> +		I915_WRITE(CLKGATE_DIS_PSL(pipe),
> +			   I915_READ(CLKGATE_DIS_PSL(pipe)) | DPFR_GATING_DIS);
> +	else
> +		I915_WRITE(CLKGATE_DIS_PSL(pipe),
> +			   I915_READ(CLKGATE_DIS_PSL(pipe)) & ~DPFR_GATING_DIS);
> +}
> +
>  static bool
>  needs_modeset(const struct drm_crtc_state *state)
>  {
> @@ -5495,6 +5508,16 @@ static bool needs_nv12_wa(struct drm_i915_private *dev_priv,
>  	return false;
>  }
>  
> +static bool needs_scalerclk_wa(struct drm_i915_private *dev_priv,
> +			       const struct intel_crtc_state *crtc_state)
> +{
> +	/* Wa_2006604312:icl */
> +	if (crtc_state->pch_pfit.enabled && IS_ICELAKE(dev_priv))
> +		return true;

After reading the w/a description I realize that this isn't quite
sufficient. Apparently we need to do the same thing for plane scaling.

I was going to suggest adding a scaled_planes bitmask (like we have
{active,c8,nv12}_planes) but actually we migth not need to do that
since we already have the scaler_users thing on skl+. I think I had
some other use in mind for scaled_planes too but I can't remember
what it was right now.

I've pushed patches 1 and 2 in the meantime. Thanks.

> +
> +	return false;
> +}
> +
>  static void intel_post_plane_update(struct intel_crtc_state *old_crtc_state)
>  {
>  	struct intel_crtc *crtc = to_intel_crtc(old_crtc_state->base.crtc);
> @@ -5528,11 +5551,13 @@ 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)) {
> +	    !needs_nv12_wa(dev_priv, pipe_config))
>  		skl_wa_827(dev_priv, crtc->pipe, false);
> -	}
> +
> +	if (needs_scalerclk_wa(dev_priv, old_crtc_state) &&
> +	    !needs_scalerclk_wa(dev_priv, pipe_config))
> +		icl_wa_scalerclkgating(dev_priv, crtc->pipe, false);
>  }
>  
>  static void intel_pre_plane_update(struct intel_crtc_state *old_crtc_state,
> @@ -5569,9 +5594,13 @@ static void intel_pre_plane_update(struct intel_crtc_state *old_crtc_state,
>  
>  	/* Display WA 827 */
>  	if (!needs_nv12_wa(dev_priv, old_crtc_state) &&
> -	    needs_nv12_wa(dev_priv, pipe_config)) {
> +	    needs_nv12_wa(dev_priv, pipe_config))
>  		skl_wa_827(dev_priv, crtc->pipe, true);
> -	}
> +
> +	/* Wa_2006604312:icl */
> +	if (!needs_scalerclk_wa(dev_priv, old_crtc_state) &&
> +	    needs_scalerclk_wa(dev_priv, pipe_config))
> +		icl_wa_scalerclkgating(dev_priv, crtc->pipe, true);
>  
>  	/*
>  	 * Vblank time updates from the shadow to live plane control register
> -- 
> 2.20.0.rc2.7.g965798d1f299

-- 
Ville Syrjälä
Intel
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