[v3,6/6] drm/i915: Have pfit calculations return an error code
diff mbox series

Message ID 20200422161917.17389-6-ville.syrjala@linux.intel.com
State New
Headers show
Series
  • [v3,1/6] drm/i915: Fix skl+ non-scaled pfit modes
Related show

Commit Message

Ville Syrjälä April 22, 2020, 4:19 p.m. UTC
From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Change intel_{gmch,pch}_panel_fitting() to return a normal
error vs. success int. We'll need this later to validate that
the margin properties aren't misconfigured.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/display/icl_dsi.c     | 10 +++++++---
 drivers/gpu/drm/i915/display/intel_dp.c    | 10 +++++-----
 drivers/gpu/drm/i915/display/intel_hdmi.c  | 23 +++++++++++-----------
 drivers/gpu/drm/i915/display/intel_lvds.c  | 13 +++++++-----
 drivers/gpu/drm/i915/display/intel_panel.c | 19 ++++++++++--------
 drivers/gpu/drm/i915/display/intel_panel.h |  6 +++---
 drivers/gpu/drm/i915/display/vlv_dsi.c     |  6 ++++--
 7 files changed, 49 insertions(+), 38 deletions(-)

Comments

Manasi Navare April 22, 2020, 9:42 p.m. UTC | #1
On Wed, Apr 22, 2020 at 07:19:17PM +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Change intel_{gmch,pch}_panel_fitting() to return a normal
> error vs. success int. We'll need this later to validate that
> the margin properties aren't misconfigured.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Yes makes total sense to return an ERR Value

Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>

Manasi

> ---
>  drivers/gpu/drm/i915/display/icl_dsi.c     | 10 +++++++---
>  drivers/gpu/drm/i915/display/intel_dp.c    | 10 +++++-----
>  drivers/gpu/drm/i915/display/intel_hdmi.c  | 23 +++++++++++-----------
>  drivers/gpu/drm/i915/display/intel_lvds.c  | 13 +++++++-----
>  drivers/gpu/drm/i915/display/intel_panel.c | 19 ++++++++++--------
>  drivers/gpu/drm/i915/display/intel_panel.h |  6 +++---
>  drivers/gpu/drm/i915/display/vlv_dsi.c     |  6 ++++--
>  7 files changed, 49 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c b/drivers/gpu/drm/i915/display/icl_dsi.c
> index 6650590f18fd..4fec5bd64920 100644
> --- a/drivers/gpu/drm/i915/display/icl_dsi.c
> +++ b/drivers/gpu/drm/i915/display/icl_dsi.c
> @@ -1526,13 +1526,17 @@ static int gen11_dsi_compute_config(struct intel_encoder *encoder,
>  						   base);
>  	struct intel_connector *intel_connector = intel_dsi->attached_connector;
>  	const struct drm_display_mode *fixed_mode =
> -					intel_connector->panel.fixed_mode;
> +		intel_connector->panel.fixed_mode;
>  	struct drm_display_mode *adjusted_mode =
> -					&pipe_config->hw.adjusted_mode;
> +		&pipe_config->hw.adjusted_mode;
> +	int ret;
>  
>  	pipe_config->output_format = INTEL_OUTPUT_FORMAT_RGB;
>  	intel_fixed_panel_mode(fixed_mode, adjusted_mode);
> -	intel_pch_panel_fitting(pipe_config, conn_state);
> +
> +	ret = intel_pch_panel_fitting(pipe_config, conn_state);
> +	if (ret)
> +		return ret;
>  
>  	adjusted_mode->flags = 0;
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 7c4c9a4f4238..5c7009b74c24 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -2354,9 +2354,7 @@ intel_dp_ycbcr420_config(struct intel_dp *intel_dp,
>  
>  	crtc_state->output_format = INTEL_OUTPUT_FORMAT_YCBCR420;
>  
> -	intel_pch_panel_fitting(crtc_state, conn_state);
> -
> -	return 0;
> +	return intel_pch_panel_fitting(crtc_state, conn_state);
>  }
>  
>  bool intel_dp_limited_color_range(const struct intel_crtc_state *crtc_state,
> @@ -2568,9 +2566,11 @@ intel_dp_compute_config(struct intel_encoder *encoder,
>  				       adjusted_mode);
>  
>  		if (HAS_GMCH(dev_priv))
> -			intel_gmch_panel_fitting(pipe_config, conn_state);
> +			ret = intel_gmch_panel_fitting(pipe_config, conn_state);
>  		else
> -			intel_pch_panel_fitting(pipe_config, conn_state);
> +			ret = intel_pch_panel_fitting(pipe_config, conn_state);
> +		if (ret)
> +			return ret;
>  	}
>  
>  	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
> diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c b/drivers/gpu/drm/i915/display/intel_hdmi.c
> index 0edbdd39f462..010f37240710 100644
> --- a/drivers/gpu/drm/i915/display/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
> @@ -2321,24 +2321,27 @@ static bool hdmi_deep_color_possible(const struct intel_crtc_state *crtc_state,
>  	return true;
>  }
>  
> -static bool
> +static int
>  intel_hdmi_ycbcr420_config(struct intel_crtc_state *crtc_state,
>  			   const struct drm_connector_state *conn_state)
>  {
>  	struct drm_connector *connector = conn_state->connector;
>  	struct drm_i915_private *i915 = to_i915(connector->dev);
> +	const struct drm_display_mode *adjusted_mode =
> +		&crtc_state->hw.adjusted_mode;
> +
> +	if (!drm_mode_is_420_only(&connector->display_info, adjusted_mode))
> +		return 0;
>  
>  	if (!connector->ycbcr_420_allowed) {
>  		drm_err(&i915->drm,
>  			"Platform doesn't support YCBCR420 output\n");
> -		return false;
> +		return -EINVAL;
>  	}
>  
>  	crtc_state->output_format = INTEL_OUTPUT_FORMAT_YCBCR420;
>  
> -	intel_pch_panel_fitting(crtc_state, conn_state);
> -
> -	return true;
> +	return intel_pch_panel_fitting(crtc_state, conn_state);
>  }
>  
>  static int intel_hdmi_port_clock(int clock, int bpc)
> @@ -2466,13 +2469,9 @@ int intel_hdmi_compute_config(struct intel_encoder *encoder,
>  	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
>  		pipe_config->pixel_multiplier = 2;
>  
> -	if (drm_mode_is_420_only(&connector->display_info, adjusted_mode)) {
> -		if (!intel_hdmi_ycbcr420_config(pipe_config, conn_state)) {
> -			drm_err(&dev_priv->drm,
> -				"Can't support YCBCR420 output\n");
> -			return -EINVAL;
> -		}
> -	}
> +	ret = intel_hdmi_ycbcr420_config(pipe_config, conn_state);
> +	if (ret)
> +		return ret;
>  
>  	pipe_config->limited_color_range =
>  		intel_hdmi_limited_color_range(pipe_config, conn_state);
> diff --git a/drivers/gpu/drm/i915/display/intel_lvds.c b/drivers/gpu/drm/i915/display/intel_lvds.c
> index ae658d9354b7..872f2a489339 100644
> --- a/drivers/gpu/drm/i915/display/intel_lvds.c
> +++ b/drivers/gpu/drm/i915/display/intel_lvds.c
> @@ -403,6 +403,7 @@ static int intel_lvds_compute_config(struct intel_encoder *intel_encoder,
>  	struct drm_display_mode *adjusted_mode = &pipe_config->hw.adjusted_mode;
>  	struct intel_crtc *intel_crtc = to_intel_crtc(pipe_config->uapi.crtc);
>  	unsigned int lvds_bpp;
> +	int ret;
>  
>  	/* Should never happen!! */
>  	if (INTEL_GEN(dev_priv) < 4 && intel_crtc->pipe == 0) {
> @@ -436,13 +437,15 @@ static int intel_lvds_compute_config(struct intel_encoder *intel_encoder,
>  	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
>  		return -EINVAL;
>  
> -	if (HAS_PCH_SPLIT(dev_priv)) {
> +	if (HAS_PCH_SPLIT(dev_priv))
>  		pipe_config->has_pch_encoder = true;
>  
> -		intel_pch_panel_fitting(pipe_config, conn_state);
> -	} else {
> -		intel_gmch_panel_fitting(pipe_config, conn_state);
> -	}
> +	if (HAS_GMCH(dev_priv))
> +		ret = intel_gmch_panel_fitting(pipe_config, conn_state);
> +	else
> +		ret = intel_pch_panel_fitting(pipe_config, conn_state);
> +	if (ret)
> +		return ret;
>  
>  	/*
>  	 * XXX: It would be nice to support lower refresh rates on the
> diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c
> index b4bb1cfc54a9..aa931f9f0d6a 100644
> --- a/drivers/gpu/drm/i915/display/intel_panel.c
> +++ b/drivers/gpu/drm/i915/display/intel_panel.c
> @@ -176,9 +176,8 @@ intel_panel_vbt_fixed_mode(struct intel_connector *connector)
>  }
>  
>  /* adjusted_mode has been preset to be the panel's fixed mode */
> -void
> -intel_pch_panel_fitting(struct intel_crtc_state *crtc_state,
> -			const struct drm_connector_state *conn_state)
> +int intel_pch_panel_fitting(struct intel_crtc_state *crtc_state,
> +			    const struct drm_connector_state *conn_state)
>  {
>  	const struct drm_display_mode *adjusted_mode =
>  		&crtc_state->hw.adjusted_mode;
> @@ -188,7 +187,7 @@ intel_pch_panel_fitting(struct intel_crtc_state *crtc_state,
>  	if (adjusted_mode->crtc_hdisplay == crtc_state->pipe_src_w &&
>  	    adjusted_mode->crtc_vdisplay == crtc_state->pipe_src_h &&
>  	    crtc_state->output_format != INTEL_OUTPUT_FORMAT_YCBCR420)
> -		return;
> +		return 0;
>  
>  	switch (conn_state->scaling_mode) {
>  	case DRM_MODE_SCALE_CENTER:
> @@ -239,12 +238,14 @@ intel_pch_panel_fitting(struct intel_crtc_state *crtc_state,
>  
>  	default:
>  		MISSING_CASE(conn_state->scaling_mode);
> -		return;
> +		return -EINVAL;
>  	}
>  
>  	drm_rect_init(&crtc_state->pch_pfit.dst,
>  		      x, y, width, height);
>  	crtc_state->pch_pfit.enabled = true;
> +
> +	return 0;
>  }
>  
>  static void
> @@ -381,8 +382,8 @@ static void i9xx_scale_aspect(struct intel_crtc_state *crtc_state,
>  	}
>  }
>  
> -void intel_gmch_panel_fitting(struct intel_crtc_state *crtc_state,
> -			      const struct drm_connector_state *conn_state)
> +int intel_gmch_panel_fitting(struct intel_crtc_state *crtc_state,
> +			     const struct drm_connector_state *conn_state)
>  {
>  	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>  	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> @@ -431,7 +432,7 @@ void intel_gmch_panel_fitting(struct intel_crtc_state *crtc_state,
>  		break;
>  	default:
>  		MISSING_CASE(conn_state->scaling_mode);
> -		return;
> +		return -EINVAL;
>  	}
>  
>  	/* 965+ wants fuzzy fitting */
> @@ -452,6 +453,8 @@ void intel_gmch_panel_fitting(struct intel_crtc_state *crtc_state,
>  	crtc_state->gmch_pfit.control = pfit_control;
>  	crtc_state->gmch_pfit.pgm_ratios = pfit_pgm_ratios;
>  	crtc_state->gmch_pfit.lvds_border_bits = border;
> +
> +	return 0;
>  }
>  
>  /**
> diff --git a/drivers/gpu/drm/i915/display/intel_panel.h b/drivers/gpu/drm/i915/display/intel_panel.h
> index a26db895038e..968b95281cb4 100644
> --- a/drivers/gpu/drm/i915/display/intel_panel.h
> +++ b/drivers/gpu/drm/i915/display/intel_panel.h
> @@ -25,10 +25,10 @@ int intel_panel_init(struct intel_panel *panel,
>  void intel_panel_fini(struct intel_panel *panel);
>  void intel_fixed_panel_mode(const struct drm_display_mode *fixed_mode,
>  			    struct drm_display_mode *adjusted_mode);
> -void intel_pch_panel_fitting(struct intel_crtc_state *crtc_state,
> +int intel_pch_panel_fitting(struct intel_crtc_state *crtc_state,
> +			    const struct drm_connector_state *conn_state);
> +int intel_gmch_panel_fitting(struct intel_crtc_state *crtc_state,
>  			     const struct drm_connector_state *conn_state);
> -void intel_gmch_panel_fitting(struct intel_crtc_state *crtc_state,
> -			      const struct drm_connector_state *conn_state);
>  void intel_panel_set_backlight_acpi(const struct drm_connector_state *conn_state,
>  				    u32 level, u32 max);
>  int intel_panel_setup_backlight(struct drm_connector *connector,
> diff --git a/drivers/gpu/drm/i915/display/vlv_dsi.c b/drivers/gpu/drm/i915/display/vlv_dsi.c
> index 9c9ea89d2107..f582ab52f0b0 100644
> --- a/drivers/gpu/drm/i915/display/vlv_dsi.c
> +++ b/drivers/gpu/drm/i915/display/vlv_dsi.c
> @@ -278,9 +278,11 @@ static int intel_dsi_compute_config(struct intel_encoder *encoder,
>  		intel_fixed_panel_mode(fixed_mode, adjusted_mode);
>  
>  		if (HAS_GMCH(dev_priv))
> -			intel_gmch_panel_fitting(pipe_config, conn_state);
> +			ret = intel_gmch_panel_fitting(pipe_config, conn_state);
>  		else
> -			intel_pch_panel_fitting(pipe_config, conn_state);
> +			ret = intel_pch_panel_fitting(pipe_config, conn_state);
> +		if (ret)
> +			return ret;
>  	}
>  
>  	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
> -- 
> 2.24.1
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

Patch
diff mbox series

diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c b/drivers/gpu/drm/i915/display/icl_dsi.c
index 6650590f18fd..4fec5bd64920 100644
--- a/drivers/gpu/drm/i915/display/icl_dsi.c
+++ b/drivers/gpu/drm/i915/display/icl_dsi.c
@@ -1526,13 +1526,17 @@  static int gen11_dsi_compute_config(struct intel_encoder *encoder,
 						   base);
 	struct intel_connector *intel_connector = intel_dsi->attached_connector;
 	const struct drm_display_mode *fixed_mode =
-					intel_connector->panel.fixed_mode;
+		intel_connector->panel.fixed_mode;
 	struct drm_display_mode *adjusted_mode =
-					&pipe_config->hw.adjusted_mode;
+		&pipe_config->hw.adjusted_mode;
+	int ret;
 
 	pipe_config->output_format = INTEL_OUTPUT_FORMAT_RGB;
 	intel_fixed_panel_mode(fixed_mode, adjusted_mode);
-	intel_pch_panel_fitting(pipe_config, conn_state);
+
+	ret = intel_pch_panel_fitting(pipe_config, conn_state);
+	if (ret)
+		return ret;
 
 	adjusted_mode->flags = 0;
 
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 7c4c9a4f4238..5c7009b74c24 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -2354,9 +2354,7 @@  intel_dp_ycbcr420_config(struct intel_dp *intel_dp,
 
 	crtc_state->output_format = INTEL_OUTPUT_FORMAT_YCBCR420;
 
-	intel_pch_panel_fitting(crtc_state, conn_state);
-
-	return 0;
+	return intel_pch_panel_fitting(crtc_state, conn_state);
 }
 
 bool intel_dp_limited_color_range(const struct intel_crtc_state *crtc_state,
@@ -2568,9 +2566,11 @@  intel_dp_compute_config(struct intel_encoder *encoder,
 				       adjusted_mode);
 
 		if (HAS_GMCH(dev_priv))
-			intel_gmch_panel_fitting(pipe_config, conn_state);
+			ret = intel_gmch_panel_fitting(pipe_config, conn_state);
 		else
-			intel_pch_panel_fitting(pipe_config, conn_state);
+			ret = intel_pch_panel_fitting(pipe_config, conn_state);
+		if (ret)
+			return ret;
 	}
 
 	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c b/drivers/gpu/drm/i915/display/intel_hdmi.c
index 0edbdd39f462..010f37240710 100644
--- a/drivers/gpu/drm/i915/display/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
@@ -2321,24 +2321,27 @@  static bool hdmi_deep_color_possible(const struct intel_crtc_state *crtc_state,
 	return true;
 }
 
-static bool
+static int
 intel_hdmi_ycbcr420_config(struct intel_crtc_state *crtc_state,
 			   const struct drm_connector_state *conn_state)
 {
 	struct drm_connector *connector = conn_state->connector;
 	struct drm_i915_private *i915 = to_i915(connector->dev);
+	const struct drm_display_mode *adjusted_mode =
+		&crtc_state->hw.adjusted_mode;
+
+	if (!drm_mode_is_420_only(&connector->display_info, adjusted_mode))
+		return 0;
 
 	if (!connector->ycbcr_420_allowed) {
 		drm_err(&i915->drm,
 			"Platform doesn't support YCBCR420 output\n");
-		return false;
+		return -EINVAL;
 	}
 
 	crtc_state->output_format = INTEL_OUTPUT_FORMAT_YCBCR420;
 
-	intel_pch_panel_fitting(crtc_state, conn_state);
-
-	return true;
+	return intel_pch_panel_fitting(crtc_state, conn_state);
 }
 
 static int intel_hdmi_port_clock(int clock, int bpc)
@@ -2466,13 +2469,9 @@  int intel_hdmi_compute_config(struct intel_encoder *encoder,
 	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
 		pipe_config->pixel_multiplier = 2;
 
-	if (drm_mode_is_420_only(&connector->display_info, adjusted_mode)) {
-		if (!intel_hdmi_ycbcr420_config(pipe_config, conn_state)) {
-			drm_err(&dev_priv->drm,
-				"Can't support YCBCR420 output\n");
-			return -EINVAL;
-		}
-	}
+	ret = intel_hdmi_ycbcr420_config(pipe_config, conn_state);
+	if (ret)
+		return ret;
 
 	pipe_config->limited_color_range =
 		intel_hdmi_limited_color_range(pipe_config, conn_state);
diff --git a/drivers/gpu/drm/i915/display/intel_lvds.c b/drivers/gpu/drm/i915/display/intel_lvds.c
index ae658d9354b7..872f2a489339 100644
--- a/drivers/gpu/drm/i915/display/intel_lvds.c
+++ b/drivers/gpu/drm/i915/display/intel_lvds.c
@@ -403,6 +403,7 @@  static int intel_lvds_compute_config(struct intel_encoder *intel_encoder,
 	struct drm_display_mode *adjusted_mode = &pipe_config->hw.adjusted_mode;
 	struct intel_crtc *intel_crtc = to_intel_crtc(pipe_config->uapi.crtc);
 	unsigned int lvds_bpp;
+	int ret;
 
 	/* Should never happen!! */
 	if (INTEL_GEN(dev_priv) < 4 && intel_crtc->pipe == 0) {
@@ -436,13 +437,15 @@  static int intel_lvds_compute_config(struct intel_encoder *intel_encoder,
 	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
 		return -EINVAL;
 
-	if (HAS_PCH_SPLIT(dev_priv)) {
+	if (HAS_PCH_SPLIT(dev_priv))
 		pipe_config->has_pch_encoder = true;
 
-		intel_pch_panel_fitting(pipe_config, conn_state);
-	} else {
-		intel_gmch_panel_fitting(pipe_config, conn_state);
-	}
+	if (HAS_GMCH(dev_priv))
+		ret = intel_gmch_panel_fitting(pipe_config, conn_state);
+	else
+		ret = intel_pch_panel_fitting(pipe_config, conn_state);
+	if (ret)
+		return ret;
 
 	/*
 	 * XXX: It would be nice to support lower refresh rates on the
diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c
index b4bb1cfc54a9..aa931f9f0d6a 100644
--- a/drivers/gpu/drm/i915/display/intel_panel.c
+++ b/drivers/gpu/drm/i915/display/intel_panel.c
@@ -176,9 +176,8 @@  intel_panel_vbt_fixed_mode(struct intel_connector *connector)
 }
 
 /* adjusted_mode has been preset to be the panel's fixed mode */
-void
-intel_pch_panel_fitting(struct intel_crtc_state *crtc_state,
-			const struct drm_connector_state *conn_state)
+int intel_pch_panel_fitting(struct intel_crtc_state *crtc_state,
+			    const struct drm_connector_state *conn_state)
 {
 	const struct drm_display_mode *adjusted_mode =
 		&crtc_state->hw.adjusted_mode;
@@ -188,7 +187,7 @@  intel_pch_panel_fitting(struct intel_crtc_state *crtc_state,
 	if (adjusted_mode->crtc_hdisplay == crtc_state->pipe_src_w &&
 	    adjusted_mode->crtc_vdisplay == crtc_state->pipe_src_h &&
 	    crtc_state->output_format != INTEL_OUTPUT_FORMAT_YCBCR420)
-		return;
+		return 0;
 
 	switch (conn_state->scaling_mode) {
 	case DRM_MODE_SCALE_CENTER:
@@ -239,12 +238,14 @@  intel_pch_panel_fitting(struct intel_crtc_state *crtc_state,
 
 	default:
 		MISSING_CASE(conn_state->scaling_mode);
-		return;
+		return -EINVAL;
 	}
 
 	drm_rect_init(&crtc_state->pch_pfit.dst,
 		      x, y, width, height);
 	crtc_state->pch_pfit.enabled = true;
+
+	return 0;
 }
 
 static void
@@ -381,8 +382,8 @@  static void i9xx_scale_aspect(struct intel_crtc_state *crtc_state,
 	}
 }
 
-void intel_gmch_panel_fitting(struct intel_crtc_state *crtc_state,
-			      const struct drm_connector_state *conn_state)
+int intel_gmch_panel_fitting(struct intel_crtc_state *crtc_state,
+			     const struct drm_connector_state *conn_state)
 {
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
@@ -431,7 +432,7 @@  void intel_gmch_panel_fitting(struct intel_crtc_state *crtc_state,
 		break;
 	default:
 		MISSING_CASE(conn_state->scaling_mode);
-		return;
+		return -EINVAL;
 	}
 
 	/* 965+ wants fuzzy fitting */
@@ -452,6 +453,8 @@  void intel_gmch_panel_fitting(struct intel_crtc_state *crtc_state,
 	crtc_state->gmch_pfit.control = pfit_control;
 	crtc_state->gmch_pfit.pgm_ratios = pfit_pgm_ratios;
 	crtc_state->gmch_pfit.lvds_border_bits = border;
+
+	return 0;
 }
 
 /**
diff --git a/drivers/gpu/drm/i915/display/intel_panel.h b/drivers/gpu/drm/i915/display/intel_panel.h
index a26db895038e..968b95281cb4 100644
--- a/drivers/gpu/drm/i915/display/intel_panel.h
+++ b/drivers/gpu/drm/i915/display/intel_panel.h
@@ -25,10 +25,10 @@  int intel_panel_init(struct intel_panel *panel,
 void intel_panel_fini(struct intel_panel *panel);
 void intel_fixed_panel_mode(const struct drm_display_mode *fixed_mode,
 			    struct drm_display_mode *adjusted_mode);
-void intel_pch_panel_fitting(struct intel_crtc_state *crtc_state,
+int intel_pch_panel_fitting(struct intel_crtc_state *crtc_state,
+			    const struct drm_connector_state *conn_state);
+int intel_gmch_panel_fitting(struct intel_crtc_state *crtc_state,
 			     const struct drm_connector_state *conn_state);
-void intel_gmch_panel_fitting(struct intel_crtc_state *crtc_state,
-			      const struct drm_connector_state *conn_state);
 void intel_panel_set_backlight_acpi(const struct drm_connector_state *conn_state,
 				    u32 level, u32 max);
 int intel_panel_setup_backlight(struct drm_connector *connector,
diff --git a/drivers/gpu/drm/i915/display/vlv_dsi.c b/drivers/gpu/drm/i915/display/vlv_dsi.c
index 9c9ea89d2107..f582ab52f0b0 100644
--- a/drivers/gpu/drm/i915/display/vlv_dsi.c
+++ b/drivers/gpu/drm/i915/display/vlv_dsi.c
@@ -278,9 +278,11 @@  static int intel_dsi_compute_config(struct intel_encoder *encoder,
 		intel_fixed_panel_mode(fixed_mode, adjusted_mode);
 
 		if (HAS_GMCH(dev_priv))
-			intel_gmch_panel_fitting(pipe_config, conn_state);
+			ret = intel_gmch_panel_fitting(pipe_config, conn_state);
 		else
-			intel_pch_panel_fitting(pipe_config, conn_state);
+			ret = intel_pch_panel_fitting(pipe_config, conn_state);
+		if (ret)
+			return ret;
 	}
 
 	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)