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, so 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.
To keep the code as simple and reliable as possible remove the intermediate next_bridge and selected_bridge variables. Get/put operations on the remaining pointer is pl->bridge.next_bridge, which is tied to the struct imx8qxp_pixel_link lifetime, are: - get reference when assigned (by of_drm_find_and_get_bridge()) - put reference before reassignment if reassignment happens - put reference when the struct imx8qxp_pixel_link embedding the struct drm_bridge is destroyed (struct drm_bridge::next_bridge) Signed-off-by: Luca Ceresoli <[email protected]> --- Changes in v6: - rewrite as suggested by Liu, removing the next_bridge pointer too and splitting the comment for maximum clarity - adapt commit message accordingly Changes in v5: - rewrite commit message after Liu's review to clarify the per-pointer get/put idea - split the if()s involved in selcting the bridge - remove intermediate selected_bridge pointer - removed Maxime's R-by, patch changed --- drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c | 27 ++++++++++++------------- 1 file changed, 13 insertions(+), 14 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..055b94d75eb6 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 +259,6 @@ 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; u32 port_id; bool found_port = false; int reg; @@ -297,20 +295,21 @@ static int imx8qxp_pixel_link_find_next_bridge(struct imx8qxp_pixel_link *pl) continue; } - struct drm_bridge *next_bridge = of_drm_find_bridge(remote); - if (!next_bridge) - return -EPROBE_DEFER; - - /* - * 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 (!pl->bridge.next_bridge) { + /* Select the first bridge by default... */ + pl->bridge.next_bridge = of_drm_find_and_get_bridge(remote); + if (!pl->bridge.next_bridge) + return -EPROBE_DEFER; + } else if (of_property_present(remote, "fsl,companion-pxl2dpi")) { + /* ... but prefer the companion PXL2DPI if present */ + drm_bridge_put(pl->bridge.next_bridge); + pl->bridge.next_bridge = of_drm_find_and_get_bridge(remote); + if (!pl->bridge.next_bridge) + return -EPROBE_DEFER; + } } pl->mst_addr = port_id - 1; - pl->next_bridge = selected_bridge; return 0; } -- 2.52.0
