Commit b99deb61 authored by Luca Ceresoli's avatar Luca Ceresoli Committed by Liu Ying
Browse files

drm/bridge: imx8qxp-pixel-link: get/put the next bridge 



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: default avatarLuca Ceresoli <luca.ceresoli@bootlin.com>
Acked-by: default avatarLiu Ying <victor.liu@nxp.com>
Signed-off-by: default avatarLiu Ying <victor.liu@nxp.com>
Link: https://lore.kernel.org/r/20260211-drm-bridge-alloc-getput-drm_of_find_bridge-v6-1-651ddfd13bdb@bootlin.com
parent 645186bf

drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c

+13 −14
Original line number Diff line number Diff line
@@ -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)

		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;



		/*

		 * 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;

		} 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;

}