linux-kernel - [PATCH v4 3/5] drm/bridge: cadence: cdns-mhdp8546-core: Set the mhdp connector earlier in atomic

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Message-ID: <20250624054448.192801-4-j-choudhary@ti.com>
Date: Tue, 24 Jun 2025 11:14:46 +0530
From: Jayesh Choudhary <j-choudhary@...com>
To: <andrzej.hajda@...el.com>, <neil.armstrong@...aro.org>, <rfoss@...nel.org>,
        <Laurent.pinchart@...asonboard.com>, <mripard@...nel.org>,
        <lumag@...nel.org>, <dianders@...omium.org>,
        <dri-devel@...ts.freedesktop.org>, <tomi.valkeinen@...asonboard.com>
CC: <jonas@...boo.se>, <jernej.skrabec@...il.com>,
        <maarten.lankhorst@...ux.intel.com>, <tzimmermann@...e.de>,
        <airlied@...il.com>, <simona@...ll.ch>, <lyude@...hat.com>,
        <luca.ceresoli@...tlin.com>, <viro@...iv.linux.org.uk>,
        <andy.yan@...k-chips.com>, <linux@...blig.org>, <javierm@...hat.com>,
        <linux-kernel@...r.kernel.org>, <devarsht@...com>,
        <j-choudhary@...com>
Subject: [PATCH v4 3/5] drm/bridge: cadence: cdns-mhdp8546-core: Set the mhdp connector earlier in atomic_enable()

In case if we get errors in cdns_mhdp_link_up() or cdns_mhdp_reg_read()
in atomic_enable, we will go to cdns_mhdp_modeset_retry_fn() and will hit
NULL pointer while trying to access the mutex. We need the connector to
be set before that. Unlike in legacy !(DBANC) cases, we do not have
connector initialised in bridge_attach(). So set the mhdp->connector
in atomic_enable() earlier to avoid possible NULL pointer.

Fixes: c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
Signed-off-by: Jayesh Choudhary <j-choudhary@...com>
---
 .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 20 +++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index 1136daaa6c90..872a2c4e1701 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -1759,12 +1759,21 @@ static void cdns_mhdp_atomic_enable(struct drm_bridge *bridge,
 	struct drm_bridge_state *new_state;
 	const struct drm_display_mode *mode;
 	u32 resp;
-	int ret;
+	int ret = 0;
 
 	dev_dbg(mhdp->dev, "bridge enable\n");
 
 	mutex_lock(&mhdp->link_mutex);
 
+	mhdp->connector = drm_atomic_get_new_connector_for_encoder(state,
+								   bridge->encoder);
+	if (WARN_ON(!mhdp->connector))
+		goto out;
+
+	conn_state = drm_atomic_get_new_connector_state(state, mhdp->connector);
+	if (WARN_ON(!conn_state))
+		goto out;
+
 	if (mhdp->plugged && !mhdp->link_up) {
 		ret = cdns_mhdp_link_up(mhdp);
 		if (ret < 0)
@@ -1784,15 +1793,6 @@ static void cdns_mhdp_atomic_enable(struct drm_bridge *bridge,
 	cdns_mhdp_reg_write(mhdp, CDNS_DPTX_CAR,
 			    resp | CDNS_VIF_CLK_EN | CDNS_VIF_CLK_RSTN);
 
-	mhdp->connector = drm_atomic_get_new_connector_for_encoder(state,
-								   bridge->encoder);
-	if (WARN_ON(!mhdp->connector))
-		goto out;
-
-	conn_state = drm_atomic_get_new_connector_state(state, mhdp->connector);
-	if (WARN_ON(!conn_state))
-		goto out;
-
 	if (mhdp->hdcp_supported &&
 	    mhdp->hw_state == MHDP_HW_READY &&
 	    conn_state->content_protection ==
-- 
2.34.1