linux-imx

/*

 * Copyright (c) 2014 Samsung Electronics Co., Ltd

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the "Software"),

 * to deal in the Software without restriction, including without limitation

 * the rights to use, copy, modify, merge, publish, distribute, sub license,

 * and/or sell copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice (including the

 * next paragraph) shall be included in all copies or substantial portions

 * of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

 * DEALINGS IN THE SOFTWARE.

 */

​

#include <linux/err.h>

#include <linux/module.h>

#include <linux/mutex.h>

​

#include <drm/drm_bridge.h>

#include <drm/drm_encoder.h>

​

#include "drm_crtc_internal.h"

​

/**

 * DOC: overview

 *

 * &struct drm_bridge represents a device that hangs on to an encoder. These are

 * handy when a regular &drm_encoder entity isn't enough to represent the entire

 * encoder chain.

 *

 * A bridge is always attached to a single &drm_encoder at a time, but can be

 * either connected to it directly, or through an intermediate bridge::

 *

 *     encoder ---> bridge B ---> bridge A

 *

 * Here, the output of the encoder feeds to bridge B, and that furthers feeds to

 * bridge A.

 *

 * The driver using the bridge is responsible to make the associations between

 * the encoder and bridges. Once these links are made, the bridges will

 * participate along with encoder functions to perform mode_set/enable/disable

 * through the ops provided in &drm_bridge_funcs.

 *

 * drm_bridge, like drm_panel, aren't drm_mode_object entities like planes,

 * CRTCs, encoders or connectors and hence are not visible to userspace. They

 * just provide additional hooks to get the desired output at the end of the

 * encoder chain.

 *

 * Bridges can also be chained up using the &drm_bridge.next pointer.

 *

 * Both legacy CRTC helpers and the new atomic modeset helpers support bridges.

 */

​

static DEFINE_MUTEX(bridge_lock);