| Message ID | 20250424-drm-bridge-convert-to-alloc-api-v2-34-8f91a404d86b@bootlin.com |
|---|---|
| State | New |
| Headers | show |
| Series | drm: convert all bridges to devm_drm_bridge_alloc() | expand |
On Thu, Apr 24, 2025 at 10:05:49PM +0200, Luca Ceresoli wrote: > This is the new API for allocating DRM bridges. > > The devm lifetime management of this driver is peculiar. The underlying > device for the panel_bridge is the panel, and the devm lifetime is tied the > panel device (panel->dev). However the panel_bridge allocation is not > performed by the panel driver, but rather by a separate entity (typically > the previous bridge in the encoder chain). > > Thus when that separate entoty is destroyed, the panel_bridge is not > removed automatically by devm, so it is rather done explicitly by calling > drm_panel_bridge_remove(). This is the function that does devm_kfree() the > panel_bridge in current code, so update it as well to put the bridge > reference instead. > > Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com> This looks fine, but we need a TODO entry to clean this up later on, and a comment on devm_drm_put_bridge that this is inherently unsafe and must not be used. Maxime
diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c index 79b009ab9396048eac57ad47631a902e949d77c6..ddd1e91970d09b93aa64f50cd9155939a12a2c6f 100644 --- a/drivers/gpu/drm/bridge/panel.c +++ b/drivers/gpu/drm/bridge/panel.c @@ -287,15 +287,14 @@ struct drm_bridge *drm_panel_bridge_add_typed(struct drm_panel *panel, if (!panel) return ERR_PTR(-EINVAL); - panel_bridge = devm_kzalloc(panel->dev, sizeof(*panel_bridge), - GFP_KERNEL); - if (!panel_bridge) - return ERR_PTR(-ENOMEM); + panel_bridge = devm_drm_bridge_alloc(panel->dev, struct panel_bridge, bridge, + &panel_bridge_bridge_funcs); + if (IS_ERR(panel_bridge)) + return (void *)panel_bridge; panel_bridge->connector_type = connector_type; panel_bridge->panel = panel; - panel_bridge->bridge.funcs = &panel_bridge_bridge_funcs; panel_bridge->bridge.of_node = panel->dev->of_node; panel_bridge->bridge.ops = DRM_BRIDGE_OP_MODES; panel_bridge->bridge.type = connector_type; @@ -327,7 +326,7 @@ void drm_panel_bridge_remove(struct drm_bridge *bridge) panel_bridge = drm_bridge_to_panel_bridge(bridge); drm_bridge_remove(bridge); - devm_kfree(panel_bridge->panel->dev, bridge); + devm_drm_put_bridge(panel_bridge->panel->dev, bridge); } EXPORT_SYMBOL(drm_panel_bridge_remove);
This is the new API for allocating DRM bridges. The devm lifetime management of this driver is peculiar. The underlying device for the panel_bridge is the panel, and the devm lifetime is tied the panel device (panel->dev). However the panel_bridge allocation is not performed by the panel driver, but rather by a separate entity (typically the previous bridge in the encoder chain). Thus when that separate entoty is destroyed, the panel_bridge is not removed automatically by devm, so it is rather done explicitly by calling drm_panel_bridge_remove(). This is the function that does devm_kfree() the panel_bridge in current code, so update it as well to put the bridge reference instead. Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com> --- drivers/gpu/drm/bridge/panel.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)