drm/bridge: Add the drm_bridge_get_prev_bridge() helper

The drm_bridge_get_prev_bridge() helper will be useful for bridge
drivers that want to do bus format negotiation with their neighbours.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191203141515.3597631-7-boris.brezillon@collabora.com
This commit is contained in:
Boris Brezillon 2019-12-03 15:15:10 +01:00
parent 4ec5c9050a
commit ac877c64c8

View file

@ -426,6 +426,22 @@ drm_bridge_get_next_bridge(struct drm_bridge *bridge)
return list_next_entry(bridge, chain_node);
}
/**
* drm_bridge_get_prev_bridge() - Get the previous bridge in the chain
* @bridge: bridge object
*
* RETURNS:
* the previous bridge in the chain, or NULL if @bridge is the first.
*/
static inline struct drm_bridge *
drm_bridge_get_prev_bridge(struct drm_bridge *bridge)
{
if (list_is_first(&bridge->chain_node, &bridge->encoder->bridge_chain))
return NULL;
return list_prev_entry(bridge, chain_node);
}
/**
* drm_bridge_chain_get_first_bridge() - Get the first bridge in the chain
* @encoder: encoder object