[PATCH v3 22/22] drm/bridge: imx8qxp-pixel-link: get/put the next bridge

Luca Ceresoli
2025-12-16T18:01:40Z

This driver obtains a bridge pointer from of_drm_find_bridge() in the probe
function and stores it until driver removal. of_drm_find_bridge() is
deprecated. Move to of_drm_find_and_get_bridge() for the bridge to be
refcounted and use bridge->next_bridge to put the reference on
deallocation.

This needs to be handled in various steps:

* the bridge returned of_drm_get_bridge() is stored in the local temporary
variable next_bridge whose scope is the for loop, so a cleanup action is
enough
* the value of next_bridge is copied into selected_bridge, potentially
more than once, so a cleanup action at function scope plus a
drm_bridge_put() in case of reassignment are enough
* on successful return selected_bridge is stored in bridge->next_bridge,
which ensures it is put when the bridge is deallocated

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
---
drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c b/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c
index 91e4f4d55469..b3050310a7f0 100644
--- a/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c
+++ b/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c
@@ -23,7 +23,6 @@

struct imx8qxp_pixel_link {
struct drm_bridge bridge;
- struct drm_bridge *next_bridge;
struct device *dev;
struct imx_sc_ipc *ipc_handle;
u8 stream_id;
@@ -140,7 +139,7 @@ static int imx8qxp_pixel_link_bridge_attach(struct drm_bridge *bridge,
}

return drm_bridge_attach(encoder,
- pl->next_bridge, bridge,
+ pl->bridge.next_bridge, bridge,
DRM_BRIDGE_ATTACH_NO_CONNECTOR);
}

@@ -260,7 +259,7 @@ static int imx8qxp_pixel_link_find_next_bridge(struct imx8qxp_pixel_link *pl)
{
struct device_node *np = pl->dev->of_node;
struct device_node *port;
- struct drm_bridge *selected_bridge = NULL;
+ struct drm_bridge *selected_bridge __free(drm_bridge_put) = NULL;
u32 port_id;
bool found_port = false;
int reg;
@@ -297,7 +296,8 @@ static int imx8qxp_pixel_link_find_next_bridge(struct imx8qxp_pixel_link *pl)
continue;
}

- struct drm_bridge *next_bridge = of_drm_find_bridge(remote);
+ struct drm_bridge *next_bridge __free(drm_bridge_put) =
+ of_drm_find_and_get_bridge(remote);
if (!next_bridge)
return -EPROBE_DEFER;

@@ -305,12 +305,14 @@ static int imx8qxp_pixel_link_find_next_bridge(struct imx8qxp_pixel_link *pl)
* Select the next bridge with companion PXL2DPI if
* present, otherwise default to the first bridge
*/
- if (!selected_bridge || of_property_present(remote, "fsl,companion-pxl2dpi"))
- selected_bridge = next_bridge;
+ if (!selected_bridge || of_property_present(remote, "fsl,companion-pxl2dpi")) {
+ drm_bridge_put(selected_bridge);
+ selected_bridge = drm_bridge_get(next_bridge);
+ }
}

pl->mst_addr = port_id - 1;
- pl->next_bridge = selected_bridge;
+ pl->bridge.next_bridge = drm_bridge_get(selected_bridge);

return 0;
}

--
2.52.0