drm/i915: Pass down rc in intel_encoder->compute_config()

Something that I completely missed when implementing the new MST VCPI
atomic helpers is that with those helpers, there's technically a chance
of us having to grab additional modeset locks in ->compute_config() and
furthermore, that means we have the potential to hit a normal modeset
deadlock. However, because ->compute_config() only returns a bool this
means we can't return -EDEADLK when we need to drop locks and try again
which means we end up just failing the atomic check permanently. Whoops.

So, fix this by modifying ->compute_config() to pass down an actual
error code instead of a bool so that the atomic check can be restarted
on modeset deadlocks.

Thanks to Ville Syrjälä for pointing this out!

Changes since v1:
* Add some newlines
* Return only -EINVAL from hsw_crt_compute_config()
* Propogate return code from intel_dp_compute_dsc_params()
* Change all of the intel_dp_compute_link_config*() variants
* Don't miss if (hdmi_port_clock_valid()) branch in
  intel_hdmi_compute_config()

Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Fixes: eceae1472467 ("drm/dp_mst: Start tracking per-port VCPI allocations")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109320
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190115200800.3121-1-lyude@redhat.com

1 files changed, 38 insertions, 33 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index fdd2cbc56fa3..d18b72b5f0b8 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1808,7 +1808,7 @@ intel_dp_adjust_compliance_config(struct intel_dp *intel_dp,
 }
 
 /* Optimize link config in order: max bpp, min clock, min lanes */
-static bool
+static int
 intel_dp_compute_link_config_wide(struct intel_dp *intel_dp,
 				  struct intel_crtc_state *pipe_config,
 				  const struct link_config_limits *limits)
@@ -1834,17 +1834,17 @@ intel_dp_compute_link_config_wide(struct intel_dp *intel_dp,
 					pipe_config->pipe_bpp = bpp;
 					pipe_config->port_clock = link_clock;
 
-					return true;
+					return 0;
 				}
 			}
 		}
 	}
 
-	return false;
+	return -EINVAL;
 }
 
 /* Optimize link config in order: max bpp, min lanes, min clock */
-static bool
+static int
 intel_dp_compute_link_config_fast(struct intel_dp *intel_dp,
 				  struct intel_crtc_state *pipe_config,
 				  const struct link_config_limits *limits)
@@ -1870,13 +1870,13 @@ intel_dp_compute_link_config_fast(struct intel_dp *intel_dp,
 					pipe_config->pipe_bpp = bpp;
 					pipe_config->port_clock = link_clock;
 
-					return true;
+					return 0;
 				}
 			}
 		}
 	}
 
-	return false;
+	return -EINVAL;
 }
 
 static int intel_dp_dsc_compute_bpp(struct intel_dp *intel_dp, u8 dsc_max_bpc)
@@ -1894,19 +1894,20 @@ static int intel_dp_dsc_compute_bpp(struct intel_dp *intel_dp, u8 dsc_max_bpc)
 	return 0;
 }
 
-static bool intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
-					struct intel_crtc_state *pipe_config,
-					struct drm_connector_state *conn_state,
-					struct link_config_limits *limits)
+static int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
+				       struct intel_crtc_state *pipe_config,
+				       struct drm_connector_state *conn_state,
+				       struct link_config_limits *limits)
 {
 	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
 	struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
 	struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
 	u8 dsc_max_bpc;
 	int pipe_bpp;
+	int ret;
 
 	if (!intel_dp_supports_dsc(intel_dp, pipe_config))
-		return false;
+		return -EINVAL;
 
 	dsc_max_bpc = min_t(u8, DP_DSC_MAX_SUPPORTED_BPC,
 			    conn_state->max_requested_bpc);
@@ -1914,7 +1915,7 @@ static bool intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
 	pipe_bpp = intel_dp_dsc_compute_bpp(intel_dp, dsc_max_bpc);
 	if (pipe_bpp < DP_DSC_MIN_SUPPORTED_BPC * 3) {
 		DRM_DEBUG_KMS("No DSC support for less than 8bpc\n");
-		return false;
+		return -EINVAL;
 	}
 
 	/*
@@ -1948,7 +1949,7 @@ static bool intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
 						     adjusted_mode->crtc_hdisplay);
 		if (!dsc_max_output_bpp || !dsc_dp_slice_count) {
 			DRM_DEBUG_KMS("Compressed BPP/Slice Count not supported\n");
-			return false;
+			return -EINVAL;
 		}
 		pipe_config->dsc_params.compressed_bpp = min_t(u16,
 							       dsc_max_output_bpp >> 4,
@@ -1965,16 +1966,19 @@ static bool intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
 			pipe_config->dsc_params.dsc_split = true;
 		} else {
 			DRM_DEBUG_KMS("Cannot split stream to use 2 VDSC instances\n");
-			return false;
+			return -EINVAL;
 		}
 	}
-	if (intel_dp_compute_dsc_params(intel_dp, pipe_config) < 0) {
+
+	ret = intel_dp_compute_dsc_params(intel_dp, pipe_config);
+	if (ret < 0) {
 		DRM_DEBUG_KMS("Cannot compute valid DSC parameters for Input Bpp = %d "
 			      "Compressed BPP = %d\n",
 			      pipe_config->pipe_bpp,
 			      pipe_config->dsc_params.compressed_bpp);
-		return false;
+		return ret;
 	}
+
 	pipe_config->dsc_params.compression_enable = true;
 	DRM_DEBUG_KMS("DP DSC computed with Input Bpp = %d "
 		      "Compressed Bpp = %d Slice Count = %d\n",
@@ -1982,10 +1986,10 @@ static bool intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
 		      pipe_config->dsc_params.compressed_bpp,
 		      pipe_config->dsc_params.slice_count);
 
-	return true;
+	return 0;
 }
 
-static bool
+static int
 intel_dp_compute_link_config(struct intel_encoder *encoder,
 			     struct intel_crtc_state *pipe_config,
 			     struct drm_connector_state *conn_state)
@@ -1994,7 +1998,7 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
 	struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
 	struct link_config_limits limits;
 	int common_len;
-	bool ret;
+	int ret;
 
 	common_len = intel_dp_common_len_rate_limit(intel_dp,
 						    intel_dp->max_link_rate);
@@ -2051,10 +2055,11 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
 							&limits);
 
 	/* enable compression if the mode doesn't fit available BW */
-	if (!ret) {
-		if (!intel_dp_dsc_compute_config(intel_dp, pipe_config,
-						 conn_state, &limits))
-			return false;
+	if (ret) {
+		ret = intel_dp_dsc_compute_config(intel_dp, pipe_config,
+						  conn_state, &limits);
+		if (ret < 0)
+			return ret;
 	}
 
 	if (pipe_config->dsc_params.compression_enable) {
@@ -2079,10 +2084,10 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
 			      intel_dp_max_data_rate(pipe_config->port_clock,
 						     pipe_config->lane_count));
 	}
-	return true;
+	return 0;
 }
 
-bool
+int
 intel_dp_compute_config(struct intel_encoder *encoder,
 			struct intel_crtc_state *pipe_config,
 			struct drm_connector_state *conn_state)
@@ -2098,6 +2103,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 		to_intel_digital_connector_state(conn_state);
 	bool constant_n = drm_dp_has_quirk(&intel_dp->desc,
 					   DP_DPCD_QUIRK_CONSTANT_N);
+	int ret;
 
 	if (HAS_PCH_SPLIT(dev_priv) && !HAS_DDI(dev_priv) && port != PORT_A)
 		pipe_config->has_pch_encoder = true;
@@ -2119,8 +2125,6 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 				       adjusted_mode);
 
 		if (INTEL_GEN(dev_priv) >= 9) {
-			int ret;
-
 			ret = skl_update_scaler_crtc(pipe_config);
 			if (ret)
 				return ret;
@@ -2135,20 +2139,21 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 	}
 
 	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
-		return false;
+		return -EINVAL;
 
 	if (HAS_GMCH_DISPLAY(dev_priv) &&
 	    adjusted_mode->flags & DRM_MODE_FLAG_INTERLACE)
-		return false;
+		return -EINVAL;
 
 	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
-		return false;
+		return -EINVAL;
 
 	pipe_config->fec_enable = !intel_dp_is_edp(intel_dp) &&
 				  intel_dp_supports_fec(intel_dp, pipe_config);
 
-	if (!intel_dp_compute_link_config(encoder, pipe_config, conn_state))
-		return false;
+	ret = intel_dp_compute_link_config(encoder, pipe_config, conn_state);
+	if (ret < 0)
+		return ret;
 
 	if (intel_conn_state->broadcast_rgb == INTEL_BROADCAST_RGB_AUTO) {
 		/*
@@ -2196,7 +2201,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 
 	intel_psr_compute_config(intel_dp, pipe_config);
 
-	return true;
+	return 0;
 }
 
 void intel_dp_set_link_params(struct intel_dp *intel_dp,