Re: [PATCH v5 1/6] drm/bridge: cadence: cdns-mhdp8546-core: Remove legacy support for connector initialisation in bridge

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

On 9/1/25 15:22, Tomi Valkeinen wrote:
> Hi,
>
> On 11/08/2025 10:58, Harikrishna Shenoy wrote:
>> From: Jayesh Choudhary <j-choudhary@ti.com>
>>
>> Now that we have DBANC framework, remove the connector initialisation code
>> as that piece of code is not called if DRM_BRIDGE_ATTACH_NO_CONNECTOR flag
>> is used. Only TI K3 platforms consume this driver and tidss (their display
>> controller) has this flag set. So this legacy support can be dropped.
>>
>> Fixes: c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
> You have a fixes tag here. What bug does this fix?

https://lore.kernel.org/all/05948e1c-fa08-4aca-b705-b2e3a228f758@ti.com/

will include explanation in cover-letter.

>> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
>> ---
>>   .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 187 +-----------------
>>   1 file changed, 10 insertions(+), 177 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> index a614d1384f71..08702ade2903 100644
>> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> @@ -739,12 +739,8 @@ static void cdns_mhdp_fw_cb(const struct firmware *fw, void *context)
>>   	spin_lock(&mhdp->start_lock);
>>   	bridge_attached = mhdp->bridge_attached;
>>   	spin_unlock(&mhdp->start_lock);
>> -	if (bridge_attached) {
>> -		if (mhdp->connector.dev)
>> -			drm_kms_helper_hotplug_event(mhdp->bridge.dev);
>> -		else
>> -			drm_bridge_hpd_notify(&mhdp->bridge, cdns_mhdp_detect(mhdp));
>> -	}
>> +	if (bridge_attached)
>> +		drm_bridge_hpd_notify(&mhdp->bridge, cdns_mhdp_detect(mhdp));
>>   }
>>   
>>   static int cdns_mhdp_load_firmware(struct cdns_mhdp_device *mhdp)
>> @@ -1444,56 +1440,6 @@ static const struct drm_edid *cdns_mhdp_edid_read(struct cdns_mhdp_device *mhdp,
>>   	return drm_edid_read_custom(connector, cdns_mhdp_get_edid_block, mhdp);
>>   }
>>   
>> -static int cdns_mhdp_get_modes(struct drm_connector *connector)
>> -{
>> -	struct cdns_mhdp_device *mhdp = connector_to_mhdp(connector);
>> -	const struct drm_edid *drm_edid;
>> -	int num_modes;
>> -
>> -	if (!mhdp->plugged)
>> -		return 0;
>> -
>> -	drm_edid = cdns_mhdp_edid_read(mhdp, connector);
>> -
>> -	drm_edid_connector_update(connector, drm_edid);
>> -
>> -	if (!drm_edid) {
>> -		dev_err(mhdp->dev, "Failed to read EDID\n");
>> -		return 0;
>> -	}
>> -
>> -	num_modes = drm_edid_connector_add_modes(connector);
>> -	drm_edid_free(drm_edid);
>> -
>> -	/*
>> -	 * HACK: Warn about unsupported display formats until we deal
>> -	 *       with them correctly.
>> -	 */
>> -	if (connector->display_info.color_formats &&
>> -	    !(connector->display_info.color_formats &
>> -	      mhdp->display_fmt.color_format))
>> -		dev_warn(mhdp->dev,
>> -			 "%s: No supported color_format found (0x%08x)\n",
>> -			__func__, connector->display_info.color_formats);
>> -
>> -	if (connector->display_info.bpc &&
>> -	    connector->display_info.bpc < mhdp->display_fmt.bpc)
>> -		dev_warn(mhdp->dev, "%s: Display bpc only %d < %d\n",
>> -			 __func__, connector->display_info.bpc,
>> -			 mhdp->display_fmt.bpc);
>> -
>> -	return num_modes;
>> -}
>> -
>> -static int cdns_mhdp_connector_detect(struct drm_connector *conn,
>> -				      struct drm_modeset_acquire_ctx *ctx,
>> -				      bool force)
>> -{
>> -	struct cdns_mhdp_device *mhdp = connector_to_mhdp(conn);
>> -
>> -	return cdns_mhdp_detect(mhdp);
>> -}
>> -
>>   static u32 cdns_mhdp_get_bpp(struct cdns_mhdp_display_fmt *fmt)
>>   {
>>   	u32 bpp;
>> @@ -1547,114 +1493,6 @@ bool cdns_mhdp_bandwidth_ok(struct cdns_mhdp_device *mhdp,
>>   	return true;
>>   }
>>   
>> -static
>> -enum drm_mode_status cdns_mhdp_mode_valid(struct drm_connector *conn,
>> -					  const struct drm_display_mode *mode)
>> -{
>> -	struct cdns_mhdp_device *mhdp = connector_to_mhdp(conn);
>> -
>> -	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 int cdns_mhdp_connector_atomic_check(struct drm_connector *conn,
>> -					    struct drm_atomic_state *state)
>> -{
>> -	struct cdns_mhdp_device *mhdp = connector_to_mhdp(conn);
>> -	struct drm_connector_state *old_state, *new_state;
>> -	struct drm_crtc_state *crtc_state;
>> -	u64 old_cp, new_cp;
>> -
>> -	if (!mhdp->hdcp_supported)
>> -		return 0;
>> -
>> -	old_state = drm_atomic_get_old_connector_state(state, conn);
>> -	new_state = drm_atomic_get_new_connector_state(state, conn);
>> -	old_cp = old_state->content_protection;
>> -	new_cp = new_state->content_protection;
>> -
>> -	if (old_state->hdcp_content_type != new_state->hdcp_content_type &&
>> -	    new_cp != DRM_MODE_CONTENT_PROTECTION_UNDESIRED) {
>> -		new_state->content_protection = DRM_MODE_CONTENT_PROTECTION_DESIRED;
>> -		goto mode_changed;
>> -	}
>> -
>> -	if (!new_state->crtc) {
>> -		if (old_cp == DRM_MODE_CONTENT_PROTECTION_ENABLED)
>> -			new_state->content_protection = DRM_MODE_CONTENT_PROTECTION_DESIRED;
>> -		return 0;
>> -	}
>> -
>> -	if (old_cp == new_cp ||
>> -	    (old_cp == DRM_MODE_CONTENT_PROTECTION_DESIRED &&
>> -	     new_cp == DRM_MODE_CONTENT_PROTECTION_ENABLED))
>> -		return 0;
>> -
>> -mode_changed:
>> -	crtc_state = drm_atomic_get_new_crtc_state(state, new_state->crtc);
>> -	crtc_state->mode_changed = true;
>> -
>> -	return 0;
>> -}
>> -
>> -static const struct drm_connector_helper_funcs cdns_mhdp_conn_helper_funcs = {
>> -	.detect_ctx = cdns_mhdp_connector_detect,
>> -	.get_modes = cdns_mhdp_get_modes,
>> -	.mode_valid = cdns_mhdp_mode_valid,
>> -	.atomic_check = cdns_mhdp_connector_atomic_check,
>> -};
>> -
>> -static const struct drm_connector_funcs cdns_mhdp_conn_funcs = {
>> -	.fill_modes = drm_helper_probe_single_connector_modes,
>> -	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
>> -	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
>> -	.reset = drm_atomic_helper_connector_reset,
>> -	.destroy = drm_connector_cleanup,
>> -};
>> -
>> -static int cdns_mhdp_connector_init(struct cdns_mhdp_device *mhdp)
>> -{
>> -	u32 bus_format = MEDIA_BUS_FMT_RGB121212_1X36;
>> -	struct drm_connector *conn = &mhdp->connector;
>> -	struct drm_bridge *bridge = &mhdp->bridge;
>> -	int ret;
>> -
>> -	conn->polled = DRM_CONNECTOR_POLL_HPD;
>> -
>> -	ret = drm_connector_init(bridge->dev, conn, &cdns_mhdp_conn_funcs,
>> -				 DRM_MODE_CONNECTOR_DisplayPort);
>> -	if (ret) {
>> -		dev_err(mhdp->dev, "Failed to initialize connector with drm\n");
>> -		return ret;
>> -	}
>> -
>> -	drm_connector_helper_add(conn, &cdns_mhdp_conn_helper_funcs);
>> -
>> -	ret = drm_display_info_set_bus_formats(&conn->display_info,
>> -					       &bus_format, 1);
>> -	if (ret)
>> -		return ret;
>> -
>> -	ret = drm_connector_attach_encoder(conn, bridge->encoder);
>> -	if (ret) {
>> -		dev_err(mhdp->dev, "Failed to attach connector to encoder\n");
>> -		return ret;
>> -	}
>> -
>> -	if (mhdp->hdcp_supported)
>> -		ret = drm_connector_attach_content_protection_property(conn, true);
>> -
>> -	return ret;
>> -}
>> -
>>   static int cdns_mhdp_attach(struct drm_bridge *bridge,
>>   			    struct drm_encoder *encoder,
>>   			    enum drm_bridge_attach_flags flags)
>> @@ -1671,9 +1509,11 @@ static int cdns_mhdp_attach(struct drm_bridge *bridge,
>>   		return ret;
>>   
>>   	if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)) {
>> -		ret = cdns_mhdp_connector_init(mhdp);
>> -		if (ret)
>> -			goto aux_unregister;
>> +		ret = -EINVAL;
>> +		dev_err(mhdp->dev,
>> +			"Connector initialisation not supported in bridge_attach %d\n",
>> +			ret);
>> +		goto aux_unregister;
>>   	}
>>   
>>   	spin_lock(&mhdp->start_lock);
>> @@ -2368,17 +2208,10 @@ static void cdns_mhdp_hpd_work(struct work_struct *work)
>>   	struct cdns_mhdp_device *mhdp = container_of(work,
>>   						     struct cdns_mhdp_device,
>>   						     hpd_work);
>> -	int ret;
>>   
>> -	ret = cdns_mhdp_update_link_status(mhdp);
>> -	if (mhdp->connector.dev) {
>> -		if (ret < 0)
>> -			schedule_work(&mhdp->modeset_retry_work);
>> -		else
>> -			drm_kms_helper_hotplug_event(mhdp->bridge.dev);
>> -	} else {
>> -		drm_bridge_hpd_notify(&mhdp->bridge, cdns_mhdp_detect(mhdp));
>> -	}
>> +	cdns_mhdp_update_link_status(mhdp);
> We don't check the return value anymore... This function is void, so we
> can't propagate the error further. We could change
> cdns_mhdp_update_link_status to return void, but maybe it's better to
> catch the error here, and print an error.
>
>   Tomi
>
will print a warn about return value in hpd_work function.
>> +
>> +	drm_bridge_hpd_notify(&mhdp->bridge, cdns_mhdp_detect(mhdp));
>>   }
>>   
>>   static int cdns_mhdp_probe(struct platform_device *pdev)