The driver calls lt8912_bridge_detach() from its lt8912_remove()
function. As the DRM core detaches bridges automatically, this leads to
calling lt8912_bridge_detach() twice. The code probably has tried to
manage the double-call with the 'is_attached' variable, but the driver
never sets the variable to false, so its of no help.

Fix the issue by dropping the call to lt8912_bridge_detach() from
lt8912_remove(), as the DRM core will handle the detach call for us,
and also drop the useless is_attached field.

Fixes: 88abfc2b9e61 ("drm/bridge: Introduce LT8912B DSI to HDMI bridge")
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 drivers/gpu/drm/bridge/lontium-lt8912b.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/bridge/lontium-lt8912b.c b/drivers/gpu/drm/bridge/lontium-lt8912b.c
index 4eaea67fb71c..0e581f6e3c88 100644
--- a/drivers/gpu/drm/bridge/lontium-lt8912b.c
+++ b/drivers/gpu/drm/bridge/lontium-lt8912b.c
@@ -45,7 +45,6 @@ struct lt8912 {
 
 	u8 data_lanes;
 	bool is_power_on;
-	bool is_attached;
 };
 
 static int lt8912_write_init_config(struct lt8912 *lt)
@@ -575,8 +574,6 @@ static int lt8912_bridge_attach(struct drm_bridge *bridge,
 	if (ret)
 		goto error;
 
-	lt->is_attached = true;
-
 	return 0;
 
 error:
@@ -588,15 +585,13 @@ static void lt8912_bridge_detach(struct drm_bridge *bridge)
 {
 	struct lt8912 *lt = bridge_to_lt8912(bridge);
 
-	if (lt->is_attached) {
-		lt8912_hard_power_off(lt);
+	lt8912_hard_power_off(lt);
 
-		if (lt->hdmi_port->ops & DRM_BRIDGE_OP_HPD)
-			drm_bridge_hpd_disable(lt->hdmi_port);
+	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);
-	}
+	drm_connector_unregister(&lt->connector);
+	drm_connector_cleanup(&lt->connector);
 }
 
 static enum drm_connector_status
@@ -750,7 +745,6 @@ static void lt8912_remove(struct i2c_client *client)
 {
 	struct lt8912 *lt = i2c_get_clientdata(client);
 
-	lt8912_bridge_detach(&lt->bridge);
 	drm_bridge_remove(&lt->bridge);
 	lt8912_free_i2c(lt);
 	lt8912_put_dt(lt);

-- 
2.34.1

On Fri, Aug 4, 2023 at 12:48 PM Tomi Valkeinen
<tomi.valkeinen@ideasonboard.com> wrote:
>
> The driver calls lt8912_bridge_detach() from its lt8912_remove()
> function. As the DRM core detaches bridges automatically, this leads to
> calling lt8912_bridge_detach() twice. The code probably has tried to
> manage the double-call with the 'is_attached' variable, but the driver
> never sets the variable to false, so its of no help.
>
> Fix the issue by dropping the call to lt8912_bridge_detach() from
> lt8912_remove(), as the DRM core will handle the detach call for us,
> and also drop the useless is_attached field.
>
> Fixes: 88abfc2b9e61 ("drm/bridge: Introduce LT8912B DSI to HDMI bridge")
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> ---
>  drivers/gpu/drm/bridge/lontium-lt8912b.c | 16 +++++-----------
>  1 file changed, 5 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/lontium-lt8912b.c b/drivers/gpu/drm/bridge/lontium-lt8912b.c
> index 4eaea67fb71c..0e581f6e3c88 100644
> --- a/drivers/gpu/drm/bridge/lontium-lt8912b.c
> +++ b/drivers/gpu/drm/bridge/lontium-lt8912b.c
> @@ -45,7 +45,6 @@ struct lt8912 {
>
>         u8 data_lanes;
>         bool is_power_on;
> -       bool is_attached;
>  };
>
>  static int lt8912_write_init_config(struct lt8912 *lt)
> @@ -575,8 +574,6 @@ static int lt8912_bridge_attach(struct drm_bridge *bridge,
>         if (ret)
>                 goto error;
>
> -       lt->is_attached = true;
> -
>         return 0;
>
>  error:
> @@ -588,15 +585,13 @@ static void lt8912_bridge_detach(struct drm_bridge *bridge)
>  {
>         struct lt8912 *lt = bridge_to_lt8912(bridge);
>
> -       if (lt->is_attached) {
> -               lt8912_hard_power_off(lt);
> +       lt8912_hard_power_off(lt);
>
> -               if (lt->hdmi_port->ops & DRM_BRIDGE_OP_HPD)
> -                       drm_bridge_hpd_disable(lt->hdmi_port);
> +       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);
> -       }
> +       drm_connector_unregister(&lt->connector);
> +       drm_connector_cleanup(&lt->connector);
>  }
>
>  static enum drm_connector_status
> @@ -750,7 +745,6 @@ static void lt8912_remove(struct i2c_client *client)
>  {
>         struct lt8912 *lt = i2c_get_clientdata(client);
>
> -       lt8912_bridge_detach(&lt->bridge);
>         drm_bridge_remove(&lt->bridge);
>         lt8912_free_i2c(lt);
>         lt8912_put_dt(lt);
>
> --
> 2.34.1
>


Reviewed-by: Robert Foss <rfoss@kernel.org>