[PATCH v6 07/26] drm/bridge: panel: forbid initializing a panel with unknown connector type

Luca Ceresoli
2025-02-06T19:01:34Z

Having an DRM_MODE_CONNECTOR_Unknown connector type is consuidered bad, and
drm_panel_bridge_add_typed() and derivatives are deprecated for this.

drm_panel_init() won't prevent initializing a panel with a
DRM_MODE_CONNECTOR_Unknown connector type. Luckily there are no in-tree
users doing it, so take this as an opportinuty to document a valid
connector type must be passed.

Returning an error if this rule is violated is not possible because
drm_panel_init() is a void function. Add at least a warning to make any
violations noticeable, especially to non-upstream drivers.

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

---

This patch was added in v6.
---
drivers/gpu/drm/bridge/panel.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
index bd61e57e1a2dd3d1eb034da4f9213a6bcb3e6dc5..58570ff6952ca313b3def084262c9bb3772272ef 100644
--- a/drivers/gpu/drm/bridge/panel.c
+++ b/drivers/gpu/drm/bridge/panel.c
@@ -40,7 +40,7 @@ static LIST_HEAD(panel_list);
* @dev: parent device of the panel
* @funcs: panel operations
* @connector_type: the connector type (DRM_MODE_CONNECTOR_*) corresponding to
- * the panel interface
+ * the panel interface (must NOT be DRM_MODE_CONNECTOR_Unknown)
*
* Initialize the panel structure for subsequent registration with
* drm_panel_add().
@@ -48,6 +48,9 @@ static LIST_HEAD(panel_list);
void drm_panel_init(struct drm_panel *panel, struct device *dev,
const struct drm_panel_funcs *funcs, int connector_type)
{
+ if (connector_type == DRM_MODE_CONNECTOR_Unknown)
+ DRM_WARN("%s: %s: a valid connector type is required!\n", __func__, dev_name(dev));
+
INIT_LIST_HEAD(&panel->list);
INIT_LIST_HEAD(&panel->followers);
mutex_init(&panel->follower_lock);

--
2.34.1