drm/bridge: cadence: cdns-mhdp8546-core: Add mode_valid hook to drm_bridge_funcs

[ Upstream commit 6dbff34 ]

Add cdns_mhdp_bridge_mode_valid() to check if specific mode is valid for
this bridge or not. In the legacy usecase with
!DRM_BRIDGE_ATTACH_NO_CONNECTOR we were using the hook from
drm_connector_helper_funcs but with DRM_BRIDGE_ATTACH_NO_CONNECTOR
we need to have mode_valid() in drm_bridge_funcs.

Without this patch, when using DRM_BRIDGE_ATTACH_NO_CONNECTOR
flag, the cdns_mhdp_bandwidth_ok() function would not be called
during  mode validation, potentially allowing modes that exceed
the bridge's bandwidth capabilities to be incorrectly marked as
valid.

Fixes: c932ced ("drm/tidss: Update encoder/bridge chain connect model")
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Link: https://patch.msgid.link/20251209120332.3559893-3-h-shenoy@ti.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: jayesh-ti

drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c

@@ -2234,6 +2234,25 @@ static struct edid *cdns_mhdp_bridge_get_edid(struct drm_bridge *bridge,
 	return cdns_mhdp_get_edid(mhdp, connector);
 }
 
+static enum drm_mode_status
+cdns_mhdp_bridge_mode_valid(struct drm_bridge *bridge,
+			    const struct drm_display_info *info,
+			    const struct drm_display_mode *mode)
+{
+	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
+
+	mutex_lock(&mhdp->link_mutex);
+
+	if (!cdns_mhdp_bandwidth_ok(mhdp, mode, mhdp->link.num_lanes,
+				    mhdp->link.rate)) {
+		mutex_unlock(&mhdp->link_mutex);
+		return MODE_CLOCK_HIGH;
+	}
+
+	mutex_unlock(&mhdp->link_mutex);
+	return MODE_OK;
+}
+
 static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
 	.atomic_enable = cdns_mhdp_atomic_enable,
 	.atomic_disable = cdns_mhdp_atomic_disable,
@@ -2248,6 +2267,7 @@ static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
 	.get_edid = cdns_mhdp_bridge_get_edid,
 	.hpd_enable = cdns_mhdp_bridge_hpd_enable,
 	.hpd_disable = cdns_mhdp_bridge_hpd_disable,
+	.mode_valid = cdns_mhdp_bridge_mode_valid,
 };
 
 static bool cdns_mhdp_detect_hpd(struct cdns_mhdp_device *mhdp, bool *hpd_pulse)