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Message-ID: <20251120121416.660781-2-h-shenoy@ti.com>
Date: Thu, 20 Nov 2025 17:44:11 +0530
From: Harikrishna Shenoy <h-shenoy@...com>
To: <Laurent.pinchart@...asonboard.com>, <airlied@...il.com>,
<andrzej.hajda@...el.com>, <andy.yan@...k-chips.com>,
<aradhya.bhatia@...ux.dev>, <devarsht@...com>, <dianders@...omium.org>,
<dri-devel@...ts.freedesktop.org>, <javierm@...hat.com>,
<jernej.skrabec@...il.com>, <jonas@...boo.se>,
<linux-kernel@...r.kernel.org>, <linux@...blig.org>,
<luca.ceresoli@...tlin.com>, <lumag@...nel.org>, <lyude@...hat.com>,
<maarten.lankhorst@...ux.intel.com>, <mordan@...ras.ru>,
<mripard@...nel.org>, <neil.armstrong@...aro.org>, <rfoss@...nel.org>,
<s-jain1@...com>, <simona@...ll.ch>, <tomi.valkeinen@...asonboard.com>,
<tzimmermann@...e.de>, <u-kumar1@...com>
Subject: [PATCH RESEND v9 1/6] drm/bridge: cadence: cdns-mhdp8546-core: Set the mhdp connector earlier in atomic_enable()
From: Jayesh Choudhary <j-choudhary@...com>
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 cases with flag
!DRM_BRIDGE_ATTACH_NO_CONNECTOR, we do not have connector initialised
in bridge_attach(), so add the mhdp->connector_ptr in device structure
to handle both cases with DRM_BRIDGE_ATTACH_NO_CONNECTOR and
!DRM_BRIDGE_ATTACH_NO_CONNECTOR, set it in atomic_enable() earlier to
avoid possible NULL pointer dereference in recovery paths like
modeset_retry_fn() with the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag set.
Fixes: c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
Signed-off-by: Jayesh Choudhary <j-choudhary@...com>
Signed-off-by: Harikrishna Shenoy <h-shenoy@...com>
---
.../drm/bridge/cadence/cdns-mhdp8546-core.c | 29 ++++++++++---------
.../drm/bridge/cadence/cdns-mhdp8546-core.h | 1 +
.../drm/bridge/cadence/cdns-mhdp8546-hdcp.c | 26 ++++++++++++-----
3 files changed, 34 insertions(+), 22 deletions(-)
diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index 38726ae1bf150..f3076e9cdabbe 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -740,7 +740,7 @@ static void cdns_mhdp_fw_cb(const struct firmware *fw, void *context)
bridge_attached = mhdp->bridge_attached;
spin_unlock(&mhdp->start_lock);
if (bridge_attached) {
- if (mhdp->connector.dev)
+ if (mhdp->connector_ptr && mhdp->connector_ptr->dev)
drm_kms_helper_hotplug_event(mhdp->bridge.dev);
else
drm_bridge_hpd_notify(&mhdp->bridge, cdns_mhdp_detect(mhdp));
@@ -1636,6 +1636,7 @@ static int cdns_mhdp_connector_init(struct cdns_mhdp_device *mhdp)
return ret;
}
+ mhdp->connector_ptr = conn;
drm_connector_helper_add(conn, &cdns_mhdp_conn_helper_funcs);
ret = drm_display_info_set_bus_formats(&conn->display_info,
@@ -1915,17 +1916,25 @@ static void cdns_mhdp_atomic_enable(struct drm_bridge *bridge,
struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
struct cdns_mhdp_bridge_state *mhdp_state;
struct drm_crtc_state *crtc_state;
- struct drm_connector *connector;
struct drm_connector_state *conn_state;
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_ptr = drm_atomic_get_new_connector_for_encoder(state,
+ bridge->encoder);
+ if (WARN_ON(!mhdp->connector_ptr))
+ goto out;
+
+ conn_state = drm_atomic_get_new_connector_state(state, mhdp->connector_ptr);
+ if (WARN_ON(!conn_state))
+ goto out;
+
if (mhdp->plugged && !mhdp->link_up) {
ret = cdns_mhdp_link_up(mhdp);
if (ret < 0)
@@ -1945,15 +1954,6 @@ 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);
- connector = drm_atomic_get_new_connector_for_encoder(state,
- bridge->encoder);
- if (WARN_ON(!connector))
- goto out;
-
- conn_state = drm_atomic_get_new_connector_state(state, connector);
- if (WARN_ON(!conn_state))
- goto out;
-
if (mhdp->hdcp_supported &&
mhdp->hw_state == MHDP_HW_READY &&
conn_state->content_protection ==
@@ -2030,6 +2030,7 @@ static void cdns_mhdp_atomic_disable(struct drm_bridge *bridge,
if (mhdp->info && mhdp->info->ops && mhdp->info->ops->disable)
mhdp->info->ops->disable(mhdp);
+ mhdp->connector_ptr = NULL;
mutex_unlock(&mhdp->link_mutex);
}
@@ -2296,7 +2297,7 @@ static void cdns_mhdp_modeset_retry_fn(struct work_struct *work)
mhdp = container_of(work, typeof(*mhdp), modeset_retry_work);
- conn = &mhdp->connector;
+ conn = mhdp->connector_ptr;
/* Grab the locks before changing connector property */
mutex_lock(&conn->dev->mode_config.mutex);
@@ -2373,7 +2374,7 @@ static void cdns_mhdp_hpd_work(struct work_struct *work)
int ret;
ret = cdns_mhdp_update_link_status(mhdp);
- if (mhdp->connector.dev) {
+ if (mhdp->connector_ptr && mhdp->connector_ptr->dev) {
if (ret < 0)
schedule_work(&mhdp->modeset_retry_work);
else
diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
index bad2fc0c73066..a76775c768956 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
@@ -376,6 +376,7 @@ struct cdns_mhdp_device {
struct mutex link_mutex;
struct drm_connector connector;
+ struct drm_connector *connector_ptr;
struct drm_bridge bridge;
struct cdns_mhdp_link link;
diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c
index 42248f179b69d..5ac2fad2f0078 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c
@@ -393,8 +393,10 @@ static int _cdns_mhdp_hdcp_disable(struct cdns_mhdp_device *mhdp)
{
int ret;
- dev_dbg(mhdp->dev, "[%s:%d] HDCP is being disabled...\n",
- mhdp->connector.name, mhdp->connector.base.id);
+ if (mhdp->connector_ptr) {
+ dev_dbg(mhdp->dev, "[%s:%d] HDCP is being disabled...\n",
+ mhdp->connector_ptr->name, mhdp->connector_ptr->base.id);
+ }
ret = cdns_mhdp_hdcp_set_config(mhdp, 0, false);
@@ -443,9 +445,11 @@ static int cdns_mhdp_hdcp_check_link(struct cdns_mhdp_device *mhdp)
if (!ret && hdcp_port_status & HDCP_PORT_STS_AUTH)
goto out;
- dev_err(mhdp->dev,
- "[%s:%d] HDCP link failed, retrying authentication\n",
- mhdp->connector.name, mhdp->connector.base.id);
+ if (mhdp->connector_ptr) {
+ dev_err(mhdp->dev,
+ "[%s:%d] HDCP link failed, retrying authentication\n",
+ mhdp->connector_ptr->name, mhdp->connector_ptr->base.id);
+ }
ret = _cdns_mhdp_hdcp_disable(mhdp);
if (ret) {
@@ -487,13 +491,19 @@ static void cdns_mhdp_hdcp_prop_work(struct work_struct *work)
struct cdns_mhdp_device *mhdp = container_of(hdcp,
struct cdns_mhdp_device,
hdcp);
- struct drm_device *dev = mhdp->connector.dev;
+ struct drm_device *dev = NULL;
struct drm_connector_state *state;
+ if (mhdp->connector_ptr)
+ dev = mhdp->connector_ptr->dev;
+
+ if (!dev)
+ return;
+
drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
mutex_lock(&mhdp->hdcp.mutex);
- if (mhdp->hdcp.value != DRM_MODE_CONTENT_PROTECTION_UNDESIRED) {
- state = mhdp->connector.state;
+ if (mhdp->connector_ptr && mhdp->hdcp.value != DRM_MODE_CONTENT_PROTECTION_UNDESIRED) {
+ state = mhdp->connector_ptr->state;
state->content_protection = mhdp->hdcp.value;
}
mutex_unlock(&mhdp->hdcp.mutex);
--
2.34.1
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