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, 7 insertions, 7 deletions

diff --git a/drivers/gpu/drm/i915/vlv_dsi.c b/drivers/gpu/drm/i915/vlv_dsi.c
index 361e962a7969..9fc8085f76dc 100644
--- a/drivers/gpu/drm/i915/vlv_dsi.c
+++ b/drivers/gpu/drm/i915/vlv_dsi.c
@@ -257,9 +257,9 @@ static void band_gap_reset(struct drm_i915_private *dev_priv)
 	mutex_unlock(&dev_priv->sb_lock);
 }
 
-static bool intel_dsi_compute_config(struct intel_encoder *encoder,
-				     struct intel_crtc_state *pipe_config,
-				     struct drm_connector_state *conn_state)
+static int intel_dsi_compute_config(struct intel_encoder *encoder,
+				    struct intel_crtc_state *pipe_config,
+				    struct drm_connector_state *conn_state)
 {
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	struct intel_dsi *intel_dsi = container_of(encoder, struct intel_dsi,
@@ -285,7 +285,7 @@ static bool intel_dsi_compute_config(struct intel_encoder *encoder,
 	}
 
 	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
-		return false;
+		return -EINVAL;
 
 	/* DSI uses short packets for sync events, so clear mode flags for DSI */
 	adjusted_mode->flags = 0;
@@ -303,16 +303,16 @@ static bool intel_dsi_compute_config(struct intel_encoder *encoder,
 
 		ret = bxt_dsi_pll_compute(encoder, pipe_config);
 		if (ret)
-			return false;
+			return -EINVAL;
 	} else {
 		ret = vlv_dsi_pll_compute(encoder, pipe_config);
 		if (ret)
-			return false;
+			return -EINVAL;
 	}
 
 	pipe_config->clock_set = true;
 
-	return true;
+	return 0;
 }
 
 static bool glk_dsi_enable_io(struct intel_encoder *encoder)