drivers/gpu/drm/drm_encoder.c - kernel/common - Git at Google

 /*
  * Copyright (c) 2016 Intel Corporation
  *
  * Permission to use, copy, modify, distribute, and sell this software and its
  * documentation for any purpose is hereby granted without fee, provided that
  * the above copyright notice appear in all copies and that both that copyright
  * notice and this permission notice appear in supporting documentation, and
  * that the name of the copyright holders not be used in advertising or
  * publicity pertaining to distribution of the software without specific,
  * written prior permission.  The copyright holders make no representations
  * about the suitability of this software for any purpose.  It is provided "as
  * is" without express or implied warranty.
  *
  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  * OF THIS SOFTWARE.
  */

 #include <linux/export.h>

 #include <drm/drm_bridge.h>
 #include <drm/drm_device.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_encoder.h>
 #include <drm/drm_managed.h>
 #include <drm/drm_print.h>

 #include "drm_crtc_internal.h"

 /**
  * DOC: overview
  *
  * Encoders represent the connecting element between the CRTC (as the overall
  * pixel pipeline, represented by &struct drm_crtc) and the connectors (as the
  * generic sink entity, represented by &struct drm_connector). An encoder takes
  * pixel data from a CRTC and converts it to a format suitable for any attached
  * connector. Encoders are objects exposed to userspace, originally to allow
  * userspace to infer cloning and connector/CRTC restrictions. Unfortunately
  * almost all drivers get this wrong, making the uabi pretty much useless. On
  * top of that the exposed restrictions are too simple for today's hardware, and
  * the recommended way to infer restrictions is by using the
  * DRM_MODE_ATOMIC_TEST_ONLY flag for the atomic IOCTL.
  *
  * Otherwise encoders aren't used in the uapi at all (any modeset request from
  * userspace directly connects a connector with a CRTC), drivers are therefore
  * free to use them however they wish. Modeset helper libraries make strong use
  * of encoders to facilitate code sharing. But for more complex settings it is
  * usually better to move shared code into a separate &drm_bridge. Compared to
  * encoders, bridges also have the benefit of being purely an internal
  * abstraction since they are not exposed to userspace at all.
  *
  * Encoders are initialized with drm_encoder_init() and cleaned up using
  * drm_encoder_cleanup().
  */
 static const struct drm_prop_enum_list drm_encoder_enum_list[] = {
 	{ DRM_MODE_ENCODER_NONE, "None" },
 	{ DRM_MODE_ENCODER_DAC, "DAC" },
 	{ DRM_MODE_ENCODER_TMDS, "TMDS" },
 	{ DRM_MODE_ENCODER_LVDS, "LVDS" },
 	{ DRM_MODE_ENCODER_TVDAC, "TV" },
 	{ DRM_MODE_ENCODER_VIRTUAL, "Virtual" },
 	{ DRM_MODE_ENCODER_DSI, "DSI" },
 	{ DRM_MODE_ENCODER_DPMST, "DP MST" },
 	{ DRM_MODE_ENCODER_DPI, "DPI" },
 };

 int drm_encoder_register_all(struct drm_device *dev)
 {
 	struct drm_encoder *encoder;
 	int ret = 0;

 	drm_for_each_encoder(encoder, dev) {
 		if (encoder->funcs && encoder->funcs->late_register)
 			ret = encoder->funcs->late_register(encoder);
 		if (ret)
 			return ret;
 	}

 	return 0;
 }

 void drm_encoder_unregister_all(struct drm_device *dev)
 {
 	struct drm_encoder *encoder;

 	drm_for_each_encoder(encoder, dev) {
 		if (encoder->funcs && encoder->funcs->early_unregister)
 			encoder->funcs->early_unregister(encoder);
 	}
 }

 __printf(5, 0)
 static int __drm_encoder_init(struct drm_device *dev,
 			      struct drm_encoder *encoder,
 			      const struct drm_encoder_funcs *funcs,
 			      int encoder_type, const char *name, va_list ap)
 {
 	int ret;

 	/* encoder index is used with 32bit bitmasks */
 	if (WARN_ON(dev->mode_config.num_encoder >= 32))
 		return -EINVAL;

 	ret = drm_mode_object_add(dev, &encoder->base, DRM_MODE_OBJECT_ENCODER);
 	if (ret)
 		return ret;

 	encoder->dev = dev;
 	encoder->encoder_type = encoder_type;
 	encoder->funcs = funcs;
 	if (name) {
 		encoder->name = kvasprintf(GFP_KERNEL, name, ap);
 	} else {
 		encoder->name = kasprintf(GFP_KERNEL, "%s-%d",
 					  drm_encoder_enum_list[encoder_type].name,
 					  encoder->base.id);
 	}
 	if (!encoder->name) {
 		ret = -ENOMEM;
 		goto out_put;
 	}

 	INIT_LIST_HEAD(&encoder->bridge_chain);
 	list_add_tail(&encoder->head, &dev->mode_config.encoder_list);
 	encoder->index = dev->mode_config.num_encoder++;

 out_put:
 	if (ret)
 		drm_mode_object_unregister(dev, &encoder->base);

 	return ret;
 }

 /**
  * drm_encoder_init - Init a preallocated encoder
  * @dev: drm device
  * @encoder: the encoder to init
  * @funcs: callbacks for this encoder
  * @encoder_type: user visible type of the encoder
  * @name: printf style format string for the encoder name, or NULL for default name
  *
  * Initializes a preallocated encoder. Encoder should be subclassed as part of
  * driver encoder objects. At driver unload time the driver's
  * &drm_encoder_funcs.destroy hook should call drm_encoder_cleanup() and kfree()
  * the encoder structure. The encoder structure should not be allocated with
  * devm_kzalloc().
  *
  * Note: consider using drmm_encoder_alloc() or drmm_encoder_init()
  * instead of drm_encoder_init() to let the DRM managed resource
  * infrastructure take care of cleanup and deallocation.
  *
  * Returns:
  * Zero on success, error code on failure.
  */
 int drm_encoder_init(struct drm_device *dev,
 		     struct drm_encoder *encoder,
 		     const struct drm_encoder_funcs *funcs,
 		     int encoder_type, const char *name, ...)
 {
 	va_list ap;
 	int ret;

 	WARN_ON(!funcs->destroy);

 	va_start(ap, name);
 	ret = __drm_encoder_init(dev, encoder, funcs, encoder_type, name, ap);
 	va_end(ap);

 	return ret;
 }
 EXPORT_SYMBOL(drm_encoder_init);

 /**
  * drm_encoder_cleanup - cleans up an initialised encoder
  * @encoder: encoder to cleanup
  *
  * Cleans up the encoder but doesn't free the object.
  */
 void drm_encoder_cleanup(struct drm_encoder *encoder)
 {
 	struct drm_device *dev = encoder->dev;
 	struct drm_bridge *bridge, *next;

 	/* Note that the encoder_list is considered to be static; should we
 	 * remove the drm_encoder at runtime we would have to decrement all
 	 * the indices on the drm_encoder after us in the encoder_list.
 	 */

 	list_for_each_entry_safe(bridge, next, &encoder->bridge_chain,
 				 chain_node)
 		drm_bridge_detach(bridge);

 	drm_mode_object_unregister(dev, &encoder->base);
 	kfree(encoder->name);
 	list_del(&encoder->head);
 	dev->mode_config.num_encoder--;

 	memset(encoder, 0, sizeof(*encoder));
 }
 EXPORT_SYMBOL(drm_encoder_cleanup);

 static void drmm_encoder_alloc_release(struct drm_device *dev, void *ptr)
 {
 	struct drm_encoder *encoder = ptr;

 	if (WARN_ON(!encoder->dev))
 		return;

 	drm_encoder_cleanup(encoder);
 }

 __printf(5, 0)
 static int __drmm_encoder_init(struct drm_device *dev,
 			       struct drm_encoder *encoder,
 			       const struct drm_encoder_funcs *funcs,
 			       int encoder_type,
 			       const char *name,
 			       va_list args)
 {
 	int ret;

 	if (drm_WARN_ON(dev, funcs && funcs->destroy))
 		return -EINVAL;

 	ret = __drm_encoder_init(dev, encoder, funcs, encoder_type, name, args);
 	if (ret)
 		return ret;

 	ret = drmm_add_action_or_reset(dev, drmm_encoder_alloc_release, encoder);
 	if (ret)
 		return ret;

 	return 0;
 }

 void *__drmm_encoder_alloc(struct drm_device *dev, size_t size, size_t offset,
 			   const struct drm_encoder_funcs *funcs,
 			   int encoder_type, const char *name, ...)
 {
 	void *container;
 	struct drm_encoder *encoder;
 	va_list ap;
 	int ret;

 	container = drmm_kzalloc(dev, size, GFP_KERNEL);
 	if (!container)
 		return ERR_PTR(-ENOMEM);

 	encoder = container + offset;

 	va_start(ap, name);
 	ret = __drmm_encoder_init(dev, encoder, funcs, encoder_type, name, ap);
 	va_end(ap);
 	if (ret)
 		return ERR_PTR(ret);

 	return container;
 }
 EXPORT_SYMBOL(__drmm_encoder_alloc);

 /**
  * drmm_encoder_init - Initialize a preallocated encoder
  * @dev: drm device
  * @encoder: the encoder to init
  * @funcs: callbacks for this encoder (optional)
  * @encoder_type: user visible type of the encoder
  * @name: printf style format string for the encoder name, or NULL for default name
  *
  * Initializes a preallocated encoder. Encoder should be subclassed as
  * part of driver encoder objects. Cleanup is automatically handled
  * through registering drm_encoder_cleanup() with drmm_add_action(). The
  * encoder structure should be allocated with drmm_kzalloc().
  *
  * The @drm_encoder_funcs.destroy hook must be NULL.
  *
  * Returns:
  * Zero on success, error code on failure.
  */
 int drmm_encoder_init(struct drm_device *dev, struct drm_encoder *encoder,
 		      const struct drm_encoder_funcs *funcs,
 		      int encoder_type, const char *name, ...)
 {
 	va_list ap;
 	int ret;

 	va_start(ap, name);
 	ret = __drmm_encoder_init(dev, encoder, funcs, encoder_type, name, ap);
 	va_end(ap);
 	if (ret)
 		return ret;

 	return 0;
 }
 EXPORT_SYMBOL(drmm_encoder_init);

 static struct drm_crtc *drm_encoder_get_crtc(struct drm_encoder *encoder)
 {
 	struct drm_connector *connector;
 	struct drm_device *dev = encoder->dev;
 	bool uses_atomic = false;
 	struct drm_connector_list_iter conn_iter;

 	/* For atomic drivers only state objects are synchronously updated and
 	 * protected by modeset locks, so check those first. */
 	drm_connector_list_iter_begin(dev, &conn_iter);
 	drm_for_each_connector_iter(connector, &conn_iter) {
 		if (!connector->state)
 			continue;

 		uses_atomic = true;

 		if (connector->state->best_encoder != encoder)
 			continue;

 		drm_connector_list_iter_end(&conn_iter);
 		return connector->state->crtc;
 	}
 	drm_connector_list_iter_end(&conn_iter);

 	/* Don't return stale data (e.g. pending async disable). */
 	if (uses_atomic)
 		return NULL;

 	return encoder->crtc;
 }

 int drm_mode_getencoder(struct drm_device *dev, void *data,
 			struct drm_file *file_priv)
 {
 	struct drm_mode_get_encoder *enc_resp = data;
 	struct drm_encoder *encoder;
 	struct drm_crtc *crtc;

 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		return -EOPNOTSUPP;

 	encoder = drm_encoder_find(dev, file_priv, enc_resp->encoder_id);
 	if (!encoder)
 		return -ENOENT;

 	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
 	crtc = drm_encoder_get_crtc(encoder);
 	if (crtc && drm_lease_held(file_priv, crtc->base.id))
 		enc_resp->crtc_id = crtc->base.id;
 	else
 		enc_resp->crtc_id = 0;
 	drm_modeset_unlock(&dev->mode_config.connection_mutex);

 	enc_resp->encoder_type = encoder->encoder_type;
 	enc_resp->encoder_id = encoder->base.id;
 	enc_resp->possible_crtcs = drm_lease_filter_crtcs(file_priv,
 							  encoder->possible_crtcs);
 	enc_resp->possible_clones = encoder->possible_clones;

 	return 0;
 }
	/*
	* Copyright (c) 2016 Intel Corporation
	*
	* Permission to use, copy, modify, distribute, and sell this software and its
	* documentation for any purpose is hereby granted without fee, provided that
	* the above copyright notice appear in all copies and that both that copyright
	* notice and this permission notice appear in supporting documentation, and
	* that the name of the copyright holders not be used in advertising or
	* publicity pertaining to distribution of the software without specific,
	* written prior permission. The copyright holders make no representations
	* about the suitability of this software for any purpose. It is provided "as
	* is" without express or implied warranty.
	*
	* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
	* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
	* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
	* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
	* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
	* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
	* OF THIS SOFTWARE.
	*/

	#include <linux/export.h>

	#include <drm/drm_bridge.h>
	#include <drm/drm_device.h>
	#include <drm/drm_drv.h>
	#include <drm/drm_encoder.h>
	#include <drm/drm_managed.h>
	#include <drm/drm_print.h>

	#include "drm_crtc_internal.h"

	/**
	* DOC: overview
	*
	* Encoders represent the connecting element between the CRTC (as the overall
	* pixel pipeline, represented by &struct drm_crtc) and the connectors (as the
	* generic sink entity, represented by &struct drm_connector). An encoder takes
	* pixel data from a CRTC and converts it to a format suitable for any attached
	* connector. Encoders are objects exposed to userspace, originally to allow
	* userspace to infer cloning and connector/CRTC restrictions. Unfortunately
	* almost all drivers get this wrong, making the uabi pretty much useless. On
	* top of that the exposed restrictions are too simple for today's hardware, and
	* the recommended way to infer restrictions is by using the
	* DRM_MODE_ATOMIC_TEST_ONLY flag for the atomic IOCTL.
	*
	* Otherwise encoders aren't used in the uapi at all (any modeset request from
	* userspace directly connects a connector with a CRTC), drivers are therefore
	* free to use them however they wish. Modeset helper libraries make strong use
	* of encoders to facilitate code sharing. But for more complex settings it is
	* usually better to move shared code into a separate &drm_bridge. Compared to
	* encoders, bridges also have the benefit of being purely an internal
	* abstraction since they are not exposed to userspace at all.
	*
	* Encoders are initialized with drm_encoder_init() and cleaned up using
	* drm_encoder_cleanup().
	*/
	static const struct drm_prop_enum_list drm_encoder_enum_list[] = {
	{ DRM_MODE_ENCODER_NONE, "None" },
	{ DRM_MODE_ENCODER_DAC, "DAC" },
	{ DRM_MODE_ENCODER_TMDS, "TMDS" },
	{ DRM_MODE_ENCODER_LVDS, "LVDS" },
	{ DRM_MODE_ENCODER_TVDAC, "TV" },
	{ DRM_MODE_ENCODER_VIRTUAL, "Virtual" },
	{ DRM_MODE_ENCODER_DSI, "DSI" },
	{ DRM_MODE_ENCODER_DPMST, "DP MST" },
	{ DRM_MODE_ENCODER_DPI, "DPI" },
	};

	int drm_encoder_register_all(struct drm_device *dev)
	{
	struct drm_encoder *encoder;
	int ret = 0;

	drm_for_each_encoder(encoder, dev) {
	if (encoder->funcs && encoder->funcs->late_register)
	ret = encoder->funcs->late_register(encoder);
	if (ret)
	return ret;
	}

	return 0;
	}

	void drm_encoder_unregister_all(struct drm_device *dev)
	{
	struct drm_encoder *encoder;

	drm_for_each_encoder(encoder, dev) {
	if (encoder->funcs && encoder->funcs->early_unregister)
	encoder->funcs->early_unregister(encoder);
	}
	}

	__printf(5, 0)
	static int __drm_encoder_init(struct drm_device *dev,
	struct drm_encoder *encoder,
	const struct drm_encoder_funcs *funcs,
	int encoder_type, const char *name, va_list ap)
	{
	int ret;

	/* encoder index is used with 32bit bitmasks */
	if (WARN_ON(dev->mode_config.num_encoder >= 32))
	return -EINVAL;

	ret = drm_mode_object_add(dev, &encoder->base, DRM_MODE_OBJECT_ENCODER);
	if (ret)
	return ret;

	encoder->dev = dev;
	encoder->encoder_type = encoder_type;
	encoder->funcs = funcs;
	if (name) {
	encoder->name = kvasprintf(GFP_KERNEL, name, ap);
	} else {
	encoder->name = kasprintf(GFP_KERNEL, "%s-%d",
	drm_encoder_enum_list[encoder_type].name,
	encoder->base.id);
	}
	if (!encoder->name) {
	ret = -ENOMEM;
	goto out_put;
	}

	INIT_LIST_HEAD(&encoder->bridge_chain);
	list_add_tail(&encoder->head, &dev->mode_config.encoder_list);
	encoder->index = dev->mode_config.num_encoder++;

	out_put:
	if (ret)
	drm_mode_object_unregister(dev, &encoder->base);

	return ret;
	}

	/**
	* drm_encoder_init - Init a preallocated encoder
	* @dev: drm device
	* @encoder: the encoder to init
	* @funcs: callbacks for this encoder
	* @encoder_type: user visible type of the encoder
	* @name: printf style format string for the encoder name, or NULL for default name
	*
	* Initializes a preallocated encoder. Encoder should be subclassed as part of
	* driver encoder objects. At driver unload time the driver's
	* &drm_encoder_funcs.destroy hook should call drm_encoder_cleanup() and kfree()
	* the encoder structure. The encoder structure should not be allocated with
	* devm_kzalloc().
	*
	* Note: consider using drmm_encoder_alloc() or drmm_encoder_init()
	* instead of drm_encoder_init() to let the DRM managed resource
	* infrastructure take care of cleanup and deallocation.
	*
	* Returns:
	* Zero on success, error code on failure.
	*/
	int drm_encoder_init(struct drm_device *dev,
	struct drm_encoder *encoder,
	const struct drm_encoder_funcs *funcs,
	int encoder_type, const char *name, ...)
	{
	va_list ap;
	int ret;

	WARN_ON(!funcs->destroy);

	va_start(ap, name);
	ret = __drm_encoder_init(dev, encoder, funcs, encoder_type, name, ap);
	va_end(ap);

	return ret;
	}
	EXPORT_SYMBOL(drm_encoder_init);

	/**
	* drm_encoder_cleanup - cleans up an initialised encoder
	* @encoder: encoder to cleanup
	*
	* Cleans up the encoder but doesn't free the object.
	*/
	void drm_encoder_cleanup(struct drm_encoder *encoder)
	{
	struct drm_device *dev = encoder->dev;
	struct drm_bridge bridge, next;

	/* Note that the encoder_list is considered to be static; should we
	* remove the drm_encoder at runtime we would have to decrement all
	* the indices on the drm_encoder after us in the encoder_list.
	*/

	list_for_each_entry_safe(bridge, next, &encoder->bridge_chain,
	chain_node)
	drm_bridge_detach(bridge);

	drm_mode_object_unregister(dev, &encoder->base);
	kfree(encoder->name);
	list_del(&encoder->head);
	dev->mode_config.num_encoder--;

	memset(encoder, 0, sizeof(*encoder));
	}
	EXPORT_SYMBOL(drm_encoder_cleanup);

	static void drmm_encoder_alloc_release(struct drm_device dev, void ptr)
	{
	struct drm_encoder *encoder = ptr;

	if (WARN_ON(!encoder->dev))
	return;

	drm_encoder_cleanup(encoder);
	}

	__printf(5, 0)
	static int __drmm_encoder_init(struct drm_device *dev,
	struct drm_encoder *encoder,
	const struct drm_encoder_funcs *funcs,
	int encoder_type,
	const char *name,
	va_list args)
	{
	int ret;

	if (drm_WARN_ON(dev, funcs && funcs->destroy))
	return -EINVAL;

	ret = __drm_encoder_init(dev, encoder, funcs, encoder_type, name, args);
	if (ret)
	return ret;

	ret = drmm_add_action_or_reset(dev, drmm_encoder_alloc_release, encoder);
	if (ret)
	return ret;

	return 0;
	}

	void __drmm_encoder_alloc(struct drm_device dev, size_t size, size_t offset,
	const struct drm_encoder_funcs *funcs,
	int encoder_type, const char *name, ...)
	{
	void *container;
	struct drm_encoder *encoder;
	va_list ap;
	int ret;

	container = drmm_kzalloc(dev, size, GFP_KERNEL);
	if (!container)
	return ERR_PTR(-ENOMEM);

	encoder = container + offset;

	va_start(ap, name);
	ret = __drmm_encoder_init(dev, encoder, funcs, encoder_type, name, ap);
	va_end(ap);
	if (ret)
	return ERR_PTR(ret);

	return container;
	}
	EXPORT_SYMBOL(__drmm_encoder_alloc);

	/**
	* drmm_encoder_init - Initialize a preallocated encoder
	* @dev: drm device
	* @encoder: the encoder to init
	* @funcs: callbacks for this encoder (optional)
	* @encoder_type: user visible type of the encoder
	* @name: printf style format string for the encoder name, or NULL for default name
	*
	* Initializes a preallocated encoder. Encoder should be subclassed as
	* part of driver encoder objects. Cleanup is automatically handled
	* through registering drm_encoder_cleanup() with drmm_add_action(). The
	* encoder structure should be allocated with drmm_kzalloc().
	*
	* The @drm_encoder_funcs.destroy hook must be NULL.
	*
	* Returns:
	* Zero on success, error code on failure.
	*/
	int drmm_encoder_init(struct drm_device dev, struct drm_encoder encoder,
	const struct drm_encoder_funcs *funcs,
	int encoder_type, const char *name, ...)
	{
	va_list ap;
	int ret;

	va_start(ap, name);
	ret = __drmm_encoder_init(dev, encoder, funcs, encoder_type, name, ap);
	va_end(ap);
	if (ret)
	return ret;

	return 0;
	}
	EXPORT_SYMBOL(drmm_encoder_init);

	static struct drm_crtc drm_encoder_get_crtc(struct drm_encoder encoder)
	{
	struct drm_connector *connector;
	struct drm_device *dev = encoder->dev;
	bool uses_atomic = false;
	struct drm_connector_list_iter conn_iter;

	/* For atomic drivers only state objects are synchronously updated and
	* protected by modeset locks, so check those first. */
	drm_connector_list_iter_begin(dev, &conn_iter);
	drm_for_each_connector_iter(connector, &conn_iter) {
	if (!connector->state)
	continue;

	uses_atomic = true;

	if (connector->state->best_encoder != encoder)
	continue;

	drm_connector_list_iter_end(&conn_iter);
	return connector->state->crtc;
	}
	drm_connector_list_iter_end(&conn_iter);

	/* Don't return stale data (e.g. pending async disable). */
	if (uses_atomic)
	return NULL;

	return encoder->crtc;
	}

	int drm_mode_getencoder(struct drm_device dev, void data,
	struct drm_file *file_priv)
	{
	struct drm_mode_get_encoder *enc_resp = data;
	struct drm_encoder *encoder;
	struct drm_crtc *crtc;

	if (!drm_core_check_feature(dev, DRIVER_MODESET))
	return -EOPNOTSUPP;

	encoder = drm_encoder_find(dev, file_priv, enc_resp->encoder_id);
	if (!encoder)
	return -ENOENT;

	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
	crtc = drm_encoder_get_crtc(encoder);
	if (crtc && drm_lease_held(file_priv, crtc->base.id))
	enc_resp->crtc_id = crtc->base.id;
	else
	enc_resp->crtc_id = 0;
	drm_modeset_unlock(&dev->mode_config.connection_mutex);

	enc_resp->encoder_type = encoder->encoder_type;
	enc_resp->encoder_id = encoder->base.id;
	enc_resp->possible_crtcs = drm_lease_filter_crtcs(file_priv,
	encoder->possible_crtcs);
	enc_resp->possible_clones = encoder->possible_clones;

	return 0;
	}