drm/vc4: Rework the encoder retrieval code

Due to a FIFO that cannot be flushed between the pixelvalve and the HDMI
controllers on BCM2711, we need to carefully disable both at boot time
if they were left enabled by the firmware.

However, at the time we're running that code, the struct drm_connector
encoder pointer isn't set yet, and thus we cannot retrieve the encoder
associated to our CRTC.

We can however make use of the fact that we have a less flexible setup
than what DRM allows where we have a 1:1 relationship between our CRTCs
and encoders (and connectors), and thus store the crtc associated to our
encoder at boot time.

We cannot do that at the time the encoders are probed though, since the
CRTCs won't be probed yet and thus we don't know at that time which CRTC
index we're going to get, so let's do this in two passes: we can first
bind all the components and then once they all are bound, we can iterate
over all the encoders to find their associated CRTC and set the pointer.

This is similar to what we're doing to set the possible_crtcs field.

Fixes: 875a4d5 ("drm/vc4: drv: Disable the CRTC at boot time")
Signed-off-by: Maxime Ripard <[email protected]>

Author: mripard

drivers/gpu/drm/vc4/vc4_crtc.c

@@ -272,6 +272,19 @@ static u32 vc4_crtc_get_fifo_full_level_bits(struct vc4_crtc *vc4_crtc,
 				   PV_CONTROL_FIFO_LEVEL);
 }
 
+static struct drm_encoder *vc4_get_connector_encoder(struct drm_connector *connector)
+{
+	struct drm_encoder *encoder;
+
+	if (drm_WARN_ON(connector->dev, hweight32(connector->possible_encoders) != 1))
+		return NULL;
+
+	drm_connector_for_each_possible_encoder(connector, encoder)
+		return encoder;
+
+	return NULL;
+}
+
 /*
  * Returns the encoder attached to the CRTC.
  *
@@ -286,9 +299,17 @@ static struct drm_encoder *vc4_get_crtc_encoder(struct drm_crtc *crtc)
 
 	drm_connector_list_iter_begin(crtc->dev, &conn_iter);
 	drm_for_each_connector_iter(connector, &conn_iter) {
-		if (connector->state->crtc == crtc) {
+		struct drm_encoder *encoder;
+		struct vc4_encoder *vc4_encoder;
+
+		encoder = vc4_get_connector_encoder(connector);
+		if (!encoder)
+			continue;
+
+		vc4_encoder = to_vc4_encoder(encoder);
+		if (vc4_encoder->crtc == crtc) {
 			drm_connector_list_iter_end(&conn_iter);
-			return connector->encoder;
+			return encoder;
 		}
 	}
 	drm_connector_list_iter_end(&conn_iter);

drivers/gpu/drm/vc4/vc4_drv.c

@@ -226,6 +226,41 @@ static int compare_dev(struct device *dev, void *data)
 	return dev == data;
 }
 
+static struct drm_crtc *vc4_drv_find_crtc(struct drm_device *drm,
+					  struct drm_encoder *encoder)
+{
+	struct drm_crtc *crtc;
+
+	if (WARN_ON(hweight32(encoder->possible_crtcs) != 1))
+		return NULL;
+
+	drm_for_each_crtc(crtc, drm) {
+		if (!drm_encoder_crtc_ok(encoder, crtc))
+			continue;
+
+		return crtc;
+	}
+
+	return NULL;
+}
+
+static void vc4_drv_set_encoder_data(struct drm_device *drm)
+{
+	struct drm_encoder *encoder;
+
+	drm_for_each_encoder(encoder, drm) {
+		struct vc4_encoder *vc4_encoder;
+		struct drm_crtc *crtc;
+
+		crtc = vc4_drv_find_crtc(drm, encoder);
+		if (WARN_ON(!crtc))
+			return;
+
+		vc4_encoder = to_vc4_encoder(encoder);
+		vc4_encoder->crtc = crtc;
+	}
+}
+
 static void vc4_match_add_drivers(struct device *dev,
 				  struct component_match **match,
 				  struct platform_driver *const *drivers,
@@ -308,6 +343,7 @@ static int vc4_drm_bind(struct device *dev)
 	ret = component_bind_all(dev, drm);
 	if (ret)
 		return ret;
+	vc4_drv_set_encoder_data(drm);
 
 	if (!vc4->firmware_kms) {
 		ret = vc4_plane_create_additional_planes(drm);

drivers/gpu/drm/vc4/vc4_drv.h

@@ -445,6 +445,16 @@ enum vc4_encoder_type {
 
 struct vc4_encoder {
 	struct drm_encoder base;
+
+	/*
+	 * At boot time, we need to be able to retrieve the CRTC for a given
+	 * connector in order to run the disable hooks below to avoid the stuck
+	 * pixel issue. Unfortunately the drm_connector->encoder pointer is
+	 * NULL at that time so we can't move up the chain, so we'll store it
+	 * ourselves here.
+	 */
+	struct drm_crtc *crtc;
+
 	enum vc4_encoder_type type;
 	u32 clock_select;