drm/vc4: hdmi: Add property to allow manual config of RGB or YCbCr

Add a custom property "Output format" that allows the overriding
of the default colourspace choice in the way that the old
firmware hdmi_pixel_encoding property did. If the chosen format is not
supported, then it will still drop back to the older behaviour.

This won't be acceptable to upstream, but it adds back the missing
functionality of hdmi_pixel_encoding.

Signed-off-by: Dave Stevenson <[email protected]>

Author: 6by9

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -599,6 +599,7 @@ static int vc4_hdmi_connector_atomic_check(struct drm_connector *connector,
 
 	if (old_state->colorspace != new_state->colorspace ||
 	    old_vc4_state->broadcast_rgb != new_vc4_state->broadcast_rgb ||
+	    old_vc4_state->requested_output_format != new_vc4_state->requested_output_format ||
 	    !drm_connector_atomic_hdr_metadata_equal(old_state, new_state)) {
 		struct drm_crtc_state *crtc_state;
 
@@ -625,6 +626,8 @@ static int vc4_hdmi_connector_get_property(struct drm_connector *connector,
 
 	if (property == vc4_hdmi->broadcast_rgb_property) {
 		*val = vc4_conn_state->broadcast_rgb;
+	} else if (property == vc4_hdmi->output_format_property) {
+		*val = vc4_conn_state->requested_output_format;
 	} else {
 		drm_dbg(drm, "Unknown property [PROP:%d:%s]\n",
 			property->base.id, property->name);
@@ -648,6 +651,9 @@ static int vc4_hdmi_connector_set_property(struct drm_connector *connector,
 	if (property == vc4_hdmi->broadcast_rgb_property) {
 		vc4_conn_state->broadcast_rgb = val;
 		return 0;
+	} else if (property == vc4_hdmi->output_format_property) {
+		vc4_conn_state->requested_output_format = val;
+		return 0;
 	}
 
 	drm_dbg(drm, "Unknown property [PROP:%d:%s]\n",
@@ -692,6 +698,7 @@ vc4_hdmi_connector_duplicate_state(struct drm_connector *connector)
 	new_state->tmds_char_rate = vc4_state->tmds_char_rate;
 	new_state->output_bpc = vc4_state->output_bpc;
 	new_state->output_format = vc4_state->output_format;
+	new_state->requested_output_format = vc4_state->requested_output_format;
 	new_state->broadcast_rgb = vc4_state->broadcast_rgb;
 	__drm_atomic_helper_connector_duplicate_state(connector, &new_state->base);
 
@@ -740,6 +747,33 @@ vc4_hdmi_attach_broadcast_rgb_property(struct drm_device *dev,
 				   VC4_HDMI_BROADCAST_RGB_AUTO);
 }
 
+static const struct drm_prop_enum_list output_format_names[] = {
+	{ VC4_HDMI_OUTPUT_AUTO, "Automatic" },
+	{ VC4_HDMI_OUTPUT_RGB, "RGB" },
+	{ VC4_HDMI_OUTPUT_YUV422, "YCbCr 4:2:2" },
+	{ VC4_HDMI_OUTPUT_YUV444, "YCbCr 4:4:4" },
+};
+
+static void
+vc4_hdmi_attach_output_format_property(struct drm_device *dev,
+				       struct vc4_hdmi *vc4_hdmi)
+{
+	struct drm_property *prop = vc4_hdmi->output_format_property;
+
+	if (!prop) {
+		prop = drm_property_create_enum(dev, DRM_MODE_PROP_ENUM,
+						"Output format",
+						output_format_names,
+						ARRAY_SIZE(output_format_names));
+		if (!prop)
+			return;
+
+		vc4_hdmi->output_format_property = prop;
+	}
+
+	drm_object_attach_property(&vc4_hdmi->connector.base, prop, 0);
+}
+
 static int vc4_hdmi_connector_init(struct drm_device *dev,
 				   struct vc4_hdmi *vc4_hdmi)
 {
@@ -790,6 +824,7 @@ static int vc4_hdmi_connector_init(struct drm_device *dev,
 	}
 
 	vc4_hdmi_attach_broadcast_rgb_property(dev, vc4_hdmi);
+	vc4_hdmi_attach_output_format_property(dev, vc4_hdmi);
 
 	drm_connector_attach_encoder(connector, encoder);
 
@@ -1960,6 +1995,10 @@ static void vc4_hdmi_encoder_atomic_mode_set(struct drm_encoder *encoder,
 		      &crtc_state->adjusted_mode);
 	vc4_hdmi->output_bpc = vc4_state->output_bpc;
 	vc4_hdmi->output_format = vc4_state->output_format;
+	vc4_hdmi->requested_output_format = vc4_state->requested_output_format;
+	memcpy(&vc4_hdmi->saved_adjusted_mode,
+	       &crtc_state->adjusted_mode,
+	       sizeof(vc4_hdmi->saved_adjusted_mode));
 	mutex_unlock(&vc4_hdmi->mutex);
 }
 
@@ -2118,6 +2157,26 @@ vc4_hdmi_encoder_compute_format(const struct vc4_hdmi *vc4_hdmi,
 	const struct drm_display_info *info = &connector->display_info;
 	unsigned int format;
 
+	if (vc4_state->requested_output_format != VC4_HDMI_OUTPUT_AUTO) {
+		drm_dbg(dev, "Trying with user requested output %u\n",
+			vc4_state->requested_output_format);
+
+		format = vc4_state->requested_output_format;
+		if (vc4_hdmi_sink_supports_format_bpc(vc4_hdmi, info, mode,
+						      format, bpc)) {
+			int ret;
+
+			ret = vc4_hdmi_encoder_compute_clock(vc4_hdmi, vc4_state,
+							     mode, bpc, format);
+			if (!ret) {
+				vc4_state->output_format = format;
+				return 0;
+			}
+		}
+
+		return -EINVAL;
+	}
+
 	drm_dbg(dev, "Trying with an RGB output\n");
 
 	format = VC4_HDMI_OUTPUT_RGB;

drivers/gpu/drm/vc4/vc4_hdmi.h

@@ -113,6 +113,7 @@ struct vc4_hdmi_audio {
 };
 
 enum vc4_hdmi_output_format {
+	VC4_HDMI_OUTPUT_AUTO,
 	VC4_HDMI_OUTPUT_RGB,
 	VC4_HDMI_OUTPUT_YUV422,
 	VC4_HDMI_OUTPUT_YUV444,
@@ -138,6 +139,7 @@ struct vc4_hdmi {
 	struct delayed_work scrambling_work;
 
 	struct drm_property *broadcast_rgb_property;
+	struct drm_property *output_format_property;
 
 	struct i2c_adapter *ddc;
 	void __iomem *hdmicore_regs;
@@ -230,6 +232,11 @@ struct vc4_hdmi {
 	 * for use outside of KMS hooks. Protected by @mutex.
 	 */
 	enum vc4_hdmi_output_format output_format;
+	/**
+	 * @requested_output_format: Copy of @vc4_connector_state.requested_output_format
+	 * for use outside of KMS hooks. Protected by @mutex.
+	 */
+	enum vc4_hdmi_output_format requested_output_format;
 
 	/**
 	 * @plugged_cb: Callback provided by hdmi-codec to indicate that an
@@ -273,6 +280,7 @@ struct vc4_hdmi_connector_state {
 	unsigned int 			output_bpc;
 	enum vc4_hdmi_output_format	output_format;
 	enum vc4_hdmi_broadcast_rgb	broadcast_rgb;
+	enum vc4_hdmi_output_format	requested_output_format;
 };
 
 #define conn_state_to_vc4_hdmi_conn_state(_state)			\