Patch "drm/bridge: lt8912b: Add hot plug detection" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/bridge: lt8912b: Add hot plug detection

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-bridge-lt8912b-add-hot-plug-detection.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit ac2522362394c2b4eda54d4b81f1135836b4edce
Author: Stefan Eichenberger <stefan.eichenberger@xxxxxxxxxxx>
Date:   Mon Nov 28 12:23:20 2022 +0100

    drm/bridge: lt8912b: Add hot plug detection
    
    [ Upstream commit 3b0a01a6a5224ed9b3f69f44edaa889b2e2b9779 ]
    
    Enable hot plug detection when it is available on the HDMI port.
    Without this connecting to a different monitor with incompatible timing
    before the 10 seconds poll period will lead to a broken display output.
    
    Fixes: 30e2ae943c26 ("drm/bridge: Introduce LT8912B DSI to HDMI bridge")
    Signed-off-by: Stefan Eichenberger <stefan.eichenberger@xxxxxxxxxxx>
    Signed-off-by: Francesco Dolcini <francesco.dolcini@xxxxxxxxxxx>
    Reviewed-by: Adrien Grassein <adrien.grassein@xxxxxxxxx>
    Reviewed-by: Robert Foss <robert.foss@xxxxxxxxxx>
    Signed-off-by: Robert Foss <robert.foss@xxxxxxxxxx>
    Link: https://patchwork.freedesktop.org/patch/msgid/20221128112320.25708-1-francesco@xxxxxxxxxx
    Stable-dep-of: 941882a0e96d ("drm/bridge: lt8912b: Fix bridge_detach")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/bridge/lontium-lt8912b.c b/drivers/gpu/drm/bridge/lontium-lt8912b.c
index 6ad3b2d1819f1..a89e505aa3811 100644
--- a/drivers/gpu/drm/bridge/lontium-lt8912b.c
+++ b/drivers/gpu/drm/bridge/lontium-lt8912b.c
@@ -506,14 +506,27 @@ static int lt8912_attach_dsi(struct lt8912 *lt)
 	return 0;
 }
 
+static void lt8912_bridge_hpd_cb(void *data, enum drm_connector_status status)
+{
+	struct lt8912 *lt = data;
+
+	if (lt->bridge.dev)
+		drm_helper_hpd_irq_event(lt->bridge.dev);
+}
+
 static int lt8912_bridge_connector_init(struct drm_bridge *bridge)
 {
 	int ret;
 	struct lt8912 *lt = bridge_to_lt8912(bridge);
 	struct drm_connector *connector = &lt->connector;
 
-	connector->polled = DRM_CONNECTOR_POLL_CONNECT |
-			    DRM_CONNECTOR_POLL_DISCONNECT;
+	if (lt->hdmi_port->ops & DRM_BRIDGE_OP_HPD) {
+		drm_bridge_hpd_enable(lt->hdmi_port, lt8912_bridge_hpd_cb, lt);
+		connector->polled = DRM_CONNECTOR_POLL_HPD;
+	} else {
+		connector->polled = DRM_CONNECTOR_POLL_CONNECT |
+				    DRM_CONNECTOR_POLL_DISCONNECT;
+	}
 
 	ret = drm_connector_init(bridge->dev, connector,
 				 &lt8912_connector_funcs,
@@ -567,6 +580,10 @@ static void lt8912_bridge_detach(struct drm_bridge *bridge)
 
 	if (lt->is_attached) {
 		lt8912_hard_power_off(lt);
+
+		if (lt->hdmi_port->ops & DRM_BRIDGE_OP_HPD)
+			drm_bridge_hpd_disable(lt->hdmi_port);
+
 		drm_connector_unregister(&lt->connector);
 		drm_connector_cleanup(&lt->connector);
 	}