Re: [PATCH v5 2/6] drm/bridge: cadence: cdns-mhdp8546*: Change drm_connector from structure to pointer

[Harikrishna Shenoy <h-shenoy@ti.com>]

On 9/1/25 15:30, Tomi Valkeinen wrote:
> Hi,
>
> On 11/08/2025 10:59, Harikrishna Shenoy wrote:
>> From: Jayesh Choudhary <j-choudhary@ti.com>
>>
>> After adding DBANC framework, mhdp->connector is not initialised during
>> bridge_attach(). The connector is however required in few driver calls
>> like cdns_mhdp_hdcp_enable() and cdns_mhdp_modeset_retry_fn().
> Does this mean that if you apply only the previous commit, mhdp will
> crash/misbehave as mdhp->connector is not initialized?
>
possible of crash/misbehave of driver due to NULL pointer de-reference 
has been discussed

in previous versions of series, will highlight it to make it more clear.

>> Use drm_connector pointer instead of structure, set it in bridge_enable()
>> and clear it in bridge_disable(), and make appropriate changes.
>>
>> Fixes: c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
> This also has a fixes tag, but I don't see any mention of any bug being
> fixed.
>
> For the subjects of the whole series, I think you can just use
> "drm/bridge: cdns-mhdp: ...". That's much shorter.
>
>   Tomi

Explanation of bug along with logs are given in previous versions of the 
series,

will include them as highlights in cover letter to make more clear.

>> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
>> ---
>>   drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 12 ++++++------
>>   drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h |  2 +-
>>   drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c |  8 ++++----
>>   3 files changed, 11 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> index 08702ade2903..c2ce3d6e5a88 100644
>> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> @@ -1755,7 +1755,6 @@ 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;
>> @@ -1785,12 +1784,12 @@ 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))
>> +	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, connector);
>> +	conn_state = drm_atomic_get_new_connector_state(state, mhdp->connector);
>>   	if (WARN_ON(!conn_state))
>>   		goto out;
>>   
>> @@ -1853,6 +1852,7 @@ static void cdns_mhdp_atomic_disable(struct drm_bridge *bridge,
>>   		cdns_mhdp_hdcp_disable(mhdp);
>>   
>>   	mhdp->bridge_enabled = false;
>> +	mhdp->connector = NULL;
>>   	cdns_mhdp_reg_read(mhdp, CDNS_DP_FRAMER_GLOBAL_CONFIG, &resp);
>>   	resp &= ~CDNS_DP_FRAMER_EN;
>>   	resp |= CDNS_DP_NO_VIDEO_MODE;
>> @@ -2134,7 +2134,7 @@ 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;
>>   
>>   	/* Grab the locks before changing connector property */
>>   	mutex_lock(&conn->dev->mode_config.mutex);
>> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
>> index bad2fc0c7306..b297db53ba28 100644
>> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
>> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
>> @@ -375,7 +375,7 @@ struct cdns_mhdp_device {
>>   	 */
>>   	struct mutex link_mutex;
>>   
>> -	struct drm_connector connector;
>> +	struct drm_connector *connector;
>>   	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 42248f179b69..59f18c3281ef 100644
>> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c
>> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c
>> @@ -394,7 +394,7 @@ 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);
>> +		mhdp->connector->name, mhdp->connector->base.id);
>>   
>>   	ret = cdns_mhdp_hdcp_set_config(mhdp, 0, false);
>>   
>> @@ -445,7 +445,7 @@ static int cdns_mhdp_hdcp_check_link(struct cdns_mhdp_device *mhdp)
>>   
>>   	dev_err(mhdp->dev,
>>   		"[%s:%d] HDCP link failed, retrying authentication\n",
>> -		mhdp->connector.name, mhdp->connector.base.id);
>> +		mhdp->connector->name, mhdp->connector->base.id);
>>   
>>   	ret = _cdns_mhdp_hdcp_disable(mhdp);
>>   	if (ret) {
>> @@ -487,13 +487,13 @@ 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 = mhdp->connector->dev;
>>   	struct drm_connector_state *state;
>>   
>>   	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;
>> +		state = mhdp->connector->state;
>>   		state->content_protection = mhdp->hdcp.value;
>>   	}
>>   	mutex_unlock(&mhdp->hdcp.mutex);