Hello Laurentiu,
On Thu Sep 11, 2025 at 1:37 PM CEST, Laurentiu Palcu wrote:
...
> +static struct drm_bridge *dcif_crtc_get_bridge(struct drm_crtc *crtc,
> + struct drm_crtc_state
> *crtc_state)
> +{
> + struct drm_connector_state *conn_state;
> + struct drm_encoder *encoder;
> + struct drm_connector *conn;
> + struct drm_bridge *bridge;
> + int i;
> +
> + for_each_new_connector_in_state(crtc_state->state, conn, conn_state, i)
> {
> + if (crtc != conn_state->crtc)
> + continue;
> +
> + encoder = conn_state->best_encoder;
> +
> + bridge = drm_bridge_chain_get_first_bridge(encoder);
The bridge returned by drm_bridge_chain_get_first_bridge() is refcounted
since v6.18-rc1 [0], so you have to put that reference...
> + if (bridge)
> + return bridge;
> + }
> +
> + return NULL;
> +}
> +
> +static void dcif_crtc_query_output_bus_format(struct drm_crtc *crtc,
> + struct drm_crtc_state *crtc_state)
> +{
> + struct dcif_crtc_state *dcif_state = to_dcif_crtc_state(crtc_state);
> + struct drm_bridge_state *bridge_state;
> + struct drm_bridge *bridge;
> +
> + dcif_state->bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> + dcif_state->bus_flags = 0;
> +
> + bridge = dcif_crtc_get_bridge(crtc, crtc_state);
> + if (!bridge)
> + return;
> +
> + bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
> bridge);
> + if (!bridge_state)
> + return;
> +
> + dcif_state->bus_format = bridge_state->input_bus_cfg.format;
> + dcif_state->bus_flags = bridge_state->input_bus_cfg.flags;
...perhaps here, when both the bridge pointer and the bridge_state pointer
referencing it go out of scope.
> +}
You can just call drm_bridge_put(bridge) there, or (at your option) use a
cleanup action:
static void dcif_crtc_query_output_bus_format(struct drm_crtc *crtc,
struct drm_crtc_state
*crtc_state)
{
struct dcif_crtc_state *dcif_state = to_dcif_crtc_state(crtc_state);
struct drm_bridge_state *bridge_state;
- struct drm_bridge *bridge;
dcif_state->bus_format = MEDIA_BUS_FMT_RGB888_1X24;
dcif_state->bus_flags = 0;
- bridge = dcif_crtc_get_bridge(crtc, crtc_state);
+ struct drm_bridge *bridge __free(drm_bridge_put) =
dcif_crtc_get_bridge(crtc, crtc_state);
if (!bridge)
return;
bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
bridge);
if (!bridge_state)
return;
dcif_state->bus_format = bridge_state->input_bus_cfg.format;
dcif_state->bus_flags = bridge_state->input_bus_cfg.flags;
}
This would call drm_bridge_put() at end of scope, i.e. end of function.
You can also have a look at recent commits involving drm_bridge_put (git
log -p -Gdrm_bridge_put v6.16..origin/master) to see how other parts of the
kernel have added drm_bridge_put().
[0]
https://gitlab.freedesktop.org/drm/misc/kernel/-/commit/8fa5909400f377351836419223c33f1131f0f7d3
Best regards,
Luca
---
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
