[Intel-gfx] [PATCH 2/2] drm/i915: Set the digital port encoder personality during modeset

[Damien Lespiau]

The ->detect() vfunc of connectors is usually responsible for setting the
encoder type on intel_digital_ports when a hotplug event happens.

However we sometimes want to force a modeset on a specific connector:
  - the user can ask the SETCRTC ioctl to use a connector that wasne
    marked as connected (because we never received a hotplug event for it).
    This can be also used in tests to do a modeset without the need of a
    plugged-in monitor.
  - the command line video= option can be used to force modesets, eg.:
    video=HDMI-A-1:1024x768e

So, before we try to do anything with the DDI encoder as part of a modeset,
we need to ensure that the personality of the encoder matches the selected
connector.

Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
---
 drivers/gpu/drm/i915/intel_ddi.c | 85 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index c8382f5..3ed2e3c 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1442,11 +1442,96 @@ static void intel_ddi_destroy(struct drm_encoder *encoder)
 	intel_dp_encoder_destroy(encoder);
 }
 
+/*
+ * The ->detect() vfunc of connectors is usually responsible for setting the
+ * encoder type on intel_digital_ports when a hotplug event happens.
+ *
+ * However we sometimes want to force a modeset on a specific connector:
+ *   - the user can ask the SETCRTC ioctl to use a connector that isn't marked
+ *     as connected (because we never received a hotplug event for it).
+ *     This can be also used in tests to do a modeset without the need of a
+ *     plugged-in monitor.
+ *   - the command line video= option can be used to force modesets, eg.:
+ *     video=HDMI-A-1:1024x768e
+ *
+ * So, before we try to do anything with the DDI encoder as part of a modeset,
+ * we need to ensure that the personality of the encoder matches the selected
+ * connector.
+ */
+static bool
+intel_ddi_ensure_encoder_type(struct intel_encoder *encoder)
+{
+	struct drm_device *dev = encoder->base.dev;
+	struct intel_connector *connector;
+
+	list_for_each_entry(connector, &dev->mode_config.connector_list,
+			    base.head) {
+		int connector_type, old_encoder_type, new_encoder_type;
+		int port;
+
+		if (connector->new_encoder != encoder)
+			continue;
+
+		connector_type = connector->base.connector_type;
+		old_encoder_type = encoder->type;
+		switch (connector_type) {
+		case DRM_MODE_CONNECTOR_HDMIA:
+		case DRM_MODE_CONNECTOR_HDMIB:
+			new_encoder_type = INTEL_OUTPUT_HDMI;
+			break;
+		case DRM_MODE_CONNECTOR_DisplayPort:
+			new_encoder_type = INTEL_OUTPUT_DISPLAYPORT;
+			break;
+		case DRM_MODE_CONNECTOR_eDP:
+			new_encoder_type = INTEL_OUTPUT_EDP;
+			continue;
+		default:
+			continue;
+		}
+
+		if (old_encoder_type == new_encoder_type)
+			continue;
+
+		port = intel_ddi_get_encoder_port(encoder);
+
+		if (old_encoder_type == INTEL_OUTPUT_EDP) {
+			DRM_ERROR("Can't change DDI %c personality to %s, "
+				  "it's an eDP DDI\n",
+				  port_name(port),
+				  intel_output_name(new_encoder_type));
+			return false;
+		}
+
+		if (connector->base.status == connector_status_connected) {
+			DRM_ERROR("Can't change DDI %c personality to %s, "
+				  "it has a connected %s device\n",
+				  port_name(port),
+				  intel_output_name(new_encoder_type),
+				  intel_output_name(old_encoder_type));
+			return false;
+		}
+
+		DRM_DEBUG_KMS("Changing DDI %c from %s to %s\n",
+			      port_name(port),
+			      intel_output_name(old_encoder_type),
+			      intel_output_name(new_encoder_type));
+
+		connector->new_encoder->type = new_encoder_type;
+	}
+
+	return true;
+}
+
 static bool intel_ddi_compute_config(struct intel_encoder *encoder,
 				     struct intel_crtc_config *pipe_config)
 {
 	int type = encoder->type;
 	int port = intel_ddi_get_encoder_port(encoder);
+	int ret;
+
+	ret = intel_ddi_ensure_encoder_type(encoder);
+	if (!ret)
+		return false;
 
 	WARN(type == INTEL_OUTPUT_UNKNOWN, "compute_config() on unknown output!\n");
 
-- 
1.8.3.1