[PATCH v3 10/11] drm: zynqmp_dp: switch to of_drm_get_bridge_by_endpoint()

Luca Ceresoli
2026-04-28T15:32:17Z

This driver calls drm_of_find_panel_or_bridge() with a NULL pointer in the
@panel parameter, thus using a reduced feature set of that function.
Replace this call with the simpler of_drm_get_bridge_by_endpoint().

Since of_drm_get_bridge_by_endpoint() increases the refcount of the
returned bridge, ensure it is put on removal. To achieve this, instead of
adding an explicit drm_bridge_put(), migrate to the bridge::next_bridge
pointer which is automatically put when the bridge is eventually freed.

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

---

Changes in v3:
- fix ERR_PTR deref when -ENODEV is returned
---
drivers/gpu/drm/xlnx/zynqmp_dp.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index 379180fb3004..c5aa236d6b74 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -353,7 +353,6 @@ struct zynqmp_dp_train_set_priv {
* @lock: Mutex protecting this struct and register access (but not AUX)
* @irq: irq
* @bridge: DRM bridge for the DP encoder
- * @next_bridge: The downstream bridge
* @test: Configuration for test mode
* @config: IP core configuration from DTS
* @aux: aux channel
@@ -385,7 +384,6 @@ struct zynqmp_dp {
struct completion aux_done;
struct mutex lock;

- struct drm_bridge *next_bridge;
struct device *dev;
struct zynqmp_dpsub *dpsub;
void __iomem *iomem;
@@ -1494,8 +1492,8 @@ static int zynqmp_dp_bridge_attach(struct drm_bridge *bridge,
return ret;
}

- if (dp->next_bridge) {
- ret = drm_bridge_attach(encoder, dp->next_bridge,
+ if (dp->bridge.next_bridge) {
+ ret = drm_bridge_attach(encoder, dp->bridge.next_bridge,
bridge, flags);
if (ret < 0)
goto error;
@@ -2461,10 +2459,15 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub)
* Acquire the next bridge in the chain. Ignore errors caused by port@5
* not being connected for backward-compatibility with older DTs.
*/
- ret = drm_of_find_panel_or_bridge(dp->dev->of_node, 5, 0, NULL,
- &dp->next_bridge);
- if (ret < 0 && ret != -ENODEV)
- goto err_reset;
+ dp->bridge.next_bridge = of_drm_get_bridge_by_endpoint(dp->dev->of_node, 5, 0);
+ if (IS_ERR(dp->bridge.next_bridge)) {
+ if (PTR_ERR(dp->bridge.next_bridge) == -ENODEV) {
+ dp->bridge.next_bridge;
+ } else {
+ ret = PTR_ERR(dp->bridge.next_bridge);
+ goto err_reset;
+ }
+ }

/* Initialize the hardware. */
dp->config.misc0 &= ~ZYNQMP_DP_MAIN_STREAM_MISC0_SYNC_LOCK;

--
2.53.0