[PATCH 3/3] drm/bridge: it66121: Select HDMI or DVI mode based on sink type

[Javier Martinez Canillas <javierm@redhat.com>]

Currently, the driver assumes that the connector sink type is always HDMI
and configures the IT66121 bridge appropriately. But configuring in this
mode and enabling the transmission of AVI infoframe packets can cause DVI
monitors to fail parsing the video signal.

To prevent this, store the connector display information sink type in the
bridge atomic state and use it to decide whether the bridge should be set
in HDMI or DVI mode, and if the AVI infoframes packets should be sent.

Assisted-by: Cursor:claude-4.6-opus
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
---

 drivers/gpu/drm/bridge/ite-it66121.c | 68 ++++++++++++++++++----------
 1 file changed, 44 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ite-it66121.c b/drivers/gpu/drm/bridge/ite-it66121.c
index a203c94a27e5..99088277d170 100644
--- a/drivers/gpu/drm/bridge/ite-it66121.c
+++ b/drivers/gpu/drm/bridge/ite-it66121.c
@@ -322,6 +322,7 @@ static inline struct it66121_ctx *bridge_to_it66121_ctx(struct drm_bridge *bridg
 
 struct it66121_bridge_state {
 	struct drm_bridge_state base;
+	bool sink_is_hdmi;
 };
 
 static inline struct it66121_bridge_state *
@@ -790,6 +791,14 @@ static int it66121_bridge_check(struct drm_bridge *bridge,
 				struct drm_connector_state *conn_state)
 {
 	struct it66121_ctx *ctx = bridge_to_it66121_ctx(bridge);
+	struct it66121_bridge_state *state =
+		to_it66121_bridge_state(bridge_state);
+
+	/* Default to HDMI to preserve legacy behavior. */
+	state->sink_is_hdmi = true;
+
+	if (conn_state && conn_state->connector)
+		state->sink_is_hdmi = conn_state->connector->display_info.is_hdmi;
 
 	if (ctx->id == ID_IT6610) {
 		/* The IT6610 only supports these settings */
@@ -809,40 +818,51 @@ void it66121_bridge_mode_set(struct drm_bridge *bridge,
 {
 	u8 buf[HDMI_INFOFRAME_SIZE(AVI)];
 	struct it66121_ctx *ctx = bridge_to_it66121_ctx(bridge);
+	struct drm_bridge_state *bridge_state =
+		drm_priv_to_bridge_state(bridge->base.state);
+	struct it66121_bridge_state *state =
+		to_it66121_bridge_state(bridge_state);
+	unsigned int hdmi_mode = state->sink_is_hdmi ?
+		IT66121_HDMI_MODE_HDMI : 0;
+	unsigned int avi_pkt = 0;
 	int ret;
 
 	mutex_lock(&ctx->lock);
 
-	ret = drm_hdmi_avi_infoframe_from_display_mode(&ctx->hdmi_avi_infoframe, ctx->connector,
-						       adjusted_mode);
-	if (ret) {
-		DRM_ERROR("Failed to setup AVI infoframe: %d\n", ret);
-		goto unlock;
-	}
+	if (hdmi_mode) {
+		ret = drm_hdmi_avi_infoframe_from_display_mode(&ctx->hdmi_avi_infoframe,
+							       ctx->connector,
+							       adjusted_mode);
+		if (ret) {
+			DRM_ERROR("Failed to setup AVI infoframe: %d\n", ret);
+			goto unlock;
+		}
 
-	ret = hdmi_avi_infoframe_pack(&ctx->hdmi_avi_infoframe, buf, sizeof(buf));
-	if (ret < 0) {
-		DRM_ERROR("Failed to pack infoframe: %d\n", ret);
-		goto unlock;
-	}
+		ret = hdmi_avi_infoframe_pack(&ctx->hdmi_avi_infoframe, buf, sizeof(buf));
+		if (ret < 0) {
+			DRM_ERROR("Failed to pack infoframe: %d\n", ret);
+			goto unlock;
+		}
 
-	/* Write new AVI infoframe packet */
-	ret = regmap_bulk_write(ctx->regmap, IT66121_AVIINFO_DB1_REG,
-				&buf[HDMI_INFOFRAME_HEADER_SIZE],
-				HDMI_AVI_INFOFRAME_SIZE);
-	if (ret)
-		goto unlock;
+		/* Write new AVI infoframe packet */
+		ret = regmap_bulk_write(ctx->regmap, IT66121_AVIINFO_DB1_REG,
+					&buf[HDMI_INFOFRAME_HEADER_SIZE],
+					HDMI_AVI_INFOFRAME_SIZE);
+		if (ret)
+			goto unlock;
 
-	if (regmap_write(ctx->regmap, IT66121_AVIINFO_CSUM_REG, buf[3]))
-		goto unlock;
+		if (regmap_write(ctx->regmap, IT66121_AVIINFO_CSUM_REG, buf[3]))
+			goto unlock;
+
+		avi_pkt = IT66121_AVI_INFO_PKT_ON | IT66121_AVI_INFO_PKT_RPT;
+	}
 
-	/* Enable AVI infoframe */
-	if (regmap_write(ctx->regmap, IT66121_AVI_INFO_PKT_REG,
-			 IT66121_AVI_INFO_PKT_ON | IT66121_AVI_INFO_PKT_RPT))
+	/* Enable or disable AVI infoframe */
+	if (regmap_write(ctx->regmap, IT66121_AVI_INFO_PKT_REG, avi_pkt))
 		goto unlock;
 
-	/* Set TX mode to HDMI */
-	if (regmap_write(ctx->regmap, IT66121_HDMI_MODE_REG, IT66121_HDMI_MODE_HDMI))
+	/* Set TX mode to HDMI or DVI */
+	if (regmap_write(ctx->regmap, IT66121_HDMI_MODE_REG, hdmi_mode))
 		goto unlock;
 
 	if ((ctx->id == ID_IT66121 || ctx->id == ID_IT66122) &&
-- 
2.54.0