Commit 10905d70 authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab
Browse files

media: media-request: implement media requests 



Add initial media request support:

1) Add MEDIA_IOC_REQUEST_ALLOC ioctl support to media-device.c
2) Add struct media_request to store request objects.
3) Add struct media_request_object to represent a request object.
4) Add MEDIA_REQUEST_IOC_QUEUE/REINIT ioctl support.

Basic lifecycle: the application allocates a request, adds
objects to it, queues the request, polls until it is completed
and can then read the final values of the objects at the time
of completion. When it closes the file descriptor the request
memory will be freed (actually, when the last user of that request
releases the request).

Drivers will bind an object to a request (the 'adds objects to it'
phase), when MEDIA_REQUEST_IOC_QUEUE is called the request is
validated (req_validate op), then queued (the req_queue op).

When done with an object it can either be unbound from the request
(e.g. when the driver has finished with a vb2 buffer) or marked as
completed (e.g. for controls associated with a buffer). When all
objects in the request are completed (or unbound), then the request
fd will signal an exception (poll).

Co-developed-by: default avatarSakari Ailus <sakari.ailus@linux.intel.com>
Co-developed-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Co-developed-by: default avatarAlexandre Courbot <acourbot@chromium.org>

Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: default avatarSakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
parent 66431c0b

drivers/media/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -3,7 +3,8 @@ 
# Makefile for the kernel multimedia device drivers.

#



media-objs	:= media-device.o media-devnode.o media-entity.o

media-objs	:= media-device.o media-devnode.o media-entity.o \

		   media-request.o



#

# I2C drivers should come before other drivers, otherwise they'll fail

drivers/media/media-device.c

+20 −4
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#include <media/media-device.h>

#include <media/media-devnode.h>

#include <media/media-entity.h>

#include <media/media-request.h>



#ifdef CONFIG_MEDIA_CONTROLLER
@@ -377,10 +378,19 @@ static long media_device_get_topology(struct media_device *mdev, void *arg) 
	return ret;

}



static long media_device_request_alloc(struct media_device *mdev,

				       int *alloc_fd)

{

	if (!mdev->ops || !mdev->ops->req_validate || !mdev->ops->req_queue)

		return -ENOTTY;



	return media_request_alloc(mdev, alloc_fd);

}



static long copy_arg_from_user(void *karg, void __user *uarg, unsigned int cmd)

{

	/* All media IOCTLs are _IOWR() */

	if (copy_from_user(karg, uarg, _IOC_SIZE(cmd)))

	if ((_IOC_DIR(cmd) & _IOC_WRITE) &&

	    copy_from_user(karg, uarg, _IOC_SIZE(cmd)))

		return -EFAULT;



	return 0;
@@ -388,8 +398,8 @@ static long copy_arg_from_user(void *karg, void __user *uarg, unsigned int cmd) 


static long copy_arg_to_user(void __user *uarg, void *karg, unsigned int cmd)

{

	/* All media IOCTLs are _IOWR() */

	if (copy_to_user(uarg, karg, _IOC_SIZE(cmd)))

	if ((_IOC_DIR(cmd) & _IOC_READ) &&

	    copy_to_user(uarg, karg, _IOC_SIZE(cmd)))

		return -EFAULT;



	return 0;
@@ -425,6 +435,7 @@ static const struct media_ioctl_info ioctl_info[] = { 
	MEDIA_IOC(ENUM_LINKS, media_device_enum_links, MEDIA_IOC_FL_GRAPH_MUTEX),

	MEDIA_IOC(SETUP_LINK, media_device_setup_link, MEDIA_IOC_FL_GRAPH_MUTEX),

	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology, MEDIA_IOC_FL_GRAPH_MUTEX),

	MEDIA_IOC(REQUEST_ALLOC, media_device_request_alloc, 0),

};



static long media_device_ioctl(struct file *filp, unsigned int cmd,
@@ -691,9 +702,13 @@ void media_device_init(struct media_device *mdev) 
	INIT_LIST_HEAD(&mdev->pads);

	INIT_LIST_HEAD(&mdev->links);

	INIT_LIST_HEAD(&mdev->entity_notify);



	mutex_init(&mdev->req_queue_mutex);

	mutex_init(&mdev->graph_mutex);

	ida_init(&mdev->entity_internal_idx);



	atomic_set(&mdev->request_id, 0);



	dev_dbg(mdev->dev, "Media device initialized\n");

}

EXPORT_SYMBOL_GPL(media_device_init);
@@ -704,6 +719,7 @@ void media_device_cleanup(struct media_device *mdev) 
	mdev->entity_internal_idx_max = 0;

	media_graph_walk_cleanup(&mdev->pm_count_walk);

	mutex_destroy(&mdev->graph_mutex);

	mutex_destroy(&mdev->req_queue_mutex);

}

EXPORT_SYMBOL_GPL(media_device_cleanup);

drivers/media/media-request.c

0 → 100644
+464 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * Media device request objects

 *

 * Copyright 2018 Cisco Systems, Inc. and/or its affiliates. All rights reserved.

 * Copyright (C) 2018 Intel Corporation

 * Copyright (C) 2018 Google, Inc.

 *

 * Author: Hans Verkuil <hans.verkuil@cisco.com>

 * Author: Sakari Ailus <sakari.ailus@linux.intel.com>

 */



#include <linux/anon_inodes.h>

#include <linux/file.h>

#include <linux/refcount.h>



#include <media/media-device.h>

#include <media/media-request.h>



static const char * const request_state[] = {

	[MEDIA_REQUEST_STATE_IDLE]	 = "idle",

	[MEDIA_REQUEST_STATE_VALIDATING] = "validating",

	[MEDIA_REQUEST_STATE_QUEUED]	 = "queued",

	[MEDIA_REQUEST_STATE_COMPLETE]	 = "complete",

	[MEDIA_REQUEST_STATE_CLEANING]	 = "cleaning",

	[MEDIA_REQUEST_STATE_UPDATING]	 = "updating",

};



static const char *

media_request_state_str(enum media_request_state state)

{

	BUILD_BUG_ON(ARRAY_SIZE(request_state) != NR_OF_MEDIA_REQUEST_STATE);



	if (WARN_ON(state >= ARRAY_SIZE(request_state)))

		return "invalid";

	return request_state[state];

}



static void media_request_clean(struct media_request *req)

{

	struct media_request_object *obj, *obj_safe;



	/* Just a sanity check. No other code path is allowed to change this. */

	WARN_ON(req->state != MEDIA_REQUEST_STATE_CLEANING);

	WARN_ON(req->updating_count);



	list_for_each_entry_safe(obj, obj_safe, &req->objects, list) {

		media_request_object_unbind(obj);

		media_request_object_put(obj);

	}



	req->updating_count = 0;

	WARN_ON(req->num_incomplete_objects);

	req->num_incomplete_objects = 0;

	wake_up_interruptible_all(&req->poll_wait);

}



static void media_request_release(struct kref *kref)

{

	struct media_request *req =

		container_of(kref, struct media_request, kref);

	struct media_device *mdev = req->mdev;



	dev_dbg(mdev->dev, "request: release %s\n", req->debug_str);



	/* No other users, no need for a spinlock */

	req->state = MEDIA_REQUEST_STATE_CLEANING;



	media_request_clean(req);



	if (mdev->ops->req_free)

		mdev->ops->req_free(req);

	else

		kfree(req);

}



void media_request_put(struct media_request *req)

{

	kref_put(&req->kref, media_request_release);

}

EXPORT_SYMBOL_GPL(media_request_put);



static int media_request_close(struct inode *inode, struct file *filp)

{

	struct media_request *req = filp->private_data;



	media_request_put(req);

	return 0;

}



static __poll_t media_request_poll(struct file *filp,

				   struct poll_table_struct *wait)

{

	struct media_request *req = filp->private_data;

	unsigned long flags;

	__poll_t ret = 0;



	if (!(poll_requested_events(wait) & EPOLLPRI))

		return 0;



	spin_lock_irqsave(&req->lock, flags);

	if (req->state == MEDIA_REQUEST_STATE_COMPLETE) {

		ret = EPOLLPRI;

		goto unlock;

	}

	if (req->state != MEDIA_REQUEST_STATE_QUEUED) {

		ret = EPOLLERR;

		goto unlock;

	}



	poll_wait(filp, &req->poll_wait, wait);



unlock:

	spin_unlock_irqrestore(&req->lock, flags);

	return ret;

}



static long media_request_ioctl_queue(struct media_request *req)

{

	struct media_device *mdev = req->mdev;

	enum media_request_state state;

	unsigned long flags;

	int ret;



	dev_dbg(mdev->dev, "request: queue %s\n", req->debug_str);



	/*

	 * Ensure the request that is validated will be the one that gets queued

	 * next by serialising the queueing process. This mutex is also used

	 * to serialize with canceling a vb2 queue and with setting values such

	 * as controls in a request.

	 */

	mutex_lock(&mdev->req_queue_mutex);



	media_request_get(req);



	spin_lock_irqsave(&req->lock, flags);

	if (req->state == MEDIA_REQUEST_STATE_IDLE)

		req->state = MEDIA_REQUEST_STATE_VALIDATING;

	state = req->state;

	spin_unlock_irqrestore(&req->lock, flags);

	if (state != MEDIA_REQUEST_STATE_VALIDATING) {

		dev_dbg(mdev->dev,

			"request: unable to queue %s, request in state %s\n",

			req->debug_str, media_request_state_str(state));

		media_request_put(req);

		mutex_unlock(&mdev->req_queue_mutex);

		return -EBUSY;

	}



	ret = mdev->ops->req_validate(req);



	/*

	 * If the req_validate was successful, then we mark the state as QUEUED

	 * and call req_queue. The reason we set the state first is that this

	 * allows req_queue to unbind or complete the queued objects in case

	 * they are immediately 'consumed'. State changes from QUEUED to another

	 * state can only happen if either the driver changes the state or if

	 * the user cancels the vb2 queue. The driver can only change the state

	 * after each object is queued through the req_queue op (and note that

	 * that op cannot fail), so setting the state to QUEUED up front is

	 * safe.

	 *

	 * The other reason for changing the state is if the vb2 queue is

	 * canceled, and that uses the req_queue_mutex which is still locked

	 * while req_queue is called, so that's safe as well.

	 */

	spin_lock_irqsave(&req->lock, flags);

	req->state = ret ? MEDIA_REQUEST_STATE_IDLE

			 : MEDIA_REQUEST_STATE_QUEUED;

	spin_unlock_irqrestore(&req->lock, flags);



	if (!ret)

		mdev->ops->req_queue(req);



	mutex_unlock(&mdev->req_queue_mutex);



	if (ret) {

		dev_dbg(mdev->dev, "request: can't queue %s (%d)\n",

			req->debug_str, ret);

		media_request_put(req);

	}



	return ret;

}



static long media_request_ioctl_reinit(struct media_request *req)

{

	struct media_device *mdev = req->mdev;

	unsigned long flags;



	spin_lock_irqsave(&req->lock, flags);

	if (req->state != MEDIA_REQUEST_STATE_IDLE &&

	    req->state != MEDIA_REQUEST_STATE_COMPLETE) {

		dev_dbg(mdev->dev,

			"request: %s not in idle or complete state, cannot reinit\n",

			req->debug_str);

		spin_unlock_irqrestore(&req->lock, flags);

		return -EBUSY;

	}

	req->state = MEDIA_REQUEST_STATE_CLEANING;

	spin_unlock_irqrestore(&req->lock, flags);



	media_request_clean(req);



	spin_lock_irqsave(&req->lock, flags);

	req->state = MEDIA_REQUEST_STATE_IDLE;

	spin_unlock_irqrestore(&req->lock, flags);



	return 0;

}



static long media_request_ioctl(struct file *filp, unsigned int cmd,

				unsigned long arg)

{

	struct media_request *req = filp->private_data;



	switch (cmd) {

	case MEDIA_REQUEST_IOC_QUEUE:

		return media_request_ioctl_queue(req);

	case MEDIA_REQUEST_IOC_REINIT:

		return media_request_ioctl_reinit(req);

	default:

		return -ENOIOCTLCMD;

	}

}



static const struct file_operations request_fops = {

	.owner = THIS_MODULE,

	.poll = media_request_poll,

	.unlocked_ioctl = media_request_ioctl,

	.release = media_request_close,

};



struct media_request *

media_request_get_by_fd(struct media_device *mdev, int request_fd)

{

	struct file *filp;

	struct media_request *req;



	if (!mdev || !mdev->ops ||

	    !mdev->ops->req_validate || !mdev->ops->req_queue)

		return ERR_PTR(-EPERM);



	filp = fget(request_fd);

	if (!filp)

		return ERR_PTR(-ENOENT);



	if (filp->f_op != &request_fops)

		goto err_fput;

	req = filp->private_data;

	if (req->mdev != mdev)

		goto err_fput;



	/*

	 * Note: as long as someone has an open filehandle of the request,

	 * the request can never be released. The fget() above ensures that

	 * even if userspace closes the request filehandle, the release()

	 * fop won't be called, so the media_request_get() always succeeds

	 * and there is no race condition where the request was released

	 * before media_request_get() is called.

	 */

	media_request_get(req);

	fput(filp);



	return req;



err_fput:

	fput(filp);



	return ERR_PTR(-ENOENT);

}

EXPORT_SYMBOL_GPL(media_request_get_by_fd);



int media_request_alloc(struct media_device *mdev, int *alloc_fd)

{

	struct media_request *req;

	struct file *filp;

	int fd;

	int ret;



	/* Either both are NULL or both are non-NULL */

	if (WARN_ON(!mdev->ops->req_alloc ^ !mdev->ops->req_free))

		return -ENOMEM;



	fd = get_unused_fd_flags(O_CLOEXEC);

	if (fd < 0)

		return fd;



	filp = anon_inode_getfile("request", &request_fops, NULL, O_CLOEXEC);

	if (IS_ERR(filp)) {

		ret = PTR_ERR(filp);

		goto err_put_fd;

	}



	if (mdev->ops->req_alloc)

		req = mdev->ops->req_alloc(mdev);

	else

		req = kzalloc(sizeof(*req), GFP_KERNEL);

	if (!req) {

		ret = -ENOMEM;

		goto err_fput;

	}



	filp->private_data = req;

	req->mdev = mdev;

	req->state = MEDIA_REQUEST_STATE_IDLE;

	req->num_incomplete_objects = 0;

	kref_init(&req->kref);

	INIT_LIST_HEAD(&req->objects);

	spin_lock_init(&req->lock);

	init_waitqueue_head(&req->poll_wait);

	req->updating_count = 0;



	*alloc_fd = fd;



	snprintf(req->debug_str, sizeof(req->debug_str), "%u:%d",

		 atomic_inc_return(&mdev->request_id), fd);

	dev_dbg(mdev->dev, "request: allocated %s\n", req->debug_str);



	fd_install(fd, filp);



	return 0;



err_fput:

	fput(filp);



err_put_fd:

	put_unused_fd(fd);



	return ret;

}



static void media_request_object_release(struct kref *kref)

{

	struct media_request_object *obj =

		container_of(kref, struct media_request_object, kref);

	struct media_request *req = obj->req;



	if (WARN_ON(req))

		media_request_object_unbind(obj);

	obj->ops->release(obj);

}



void media_request_object_put(struct media_request_object *obj)

{

	kref_put(&obj->kref, media_request_object_release);

}

EXPORT_SYMBOL_GPL(media_request_object_put);



void media_request_object_init(struct media_request_object *obj)

{

	obj->ops = NULL;

	obj->req = NULL;

	obj->priv = NULL;

	obj->completed = false;

	INIT_LIST_HEAD(&obj->list);

	kref_init(&obj->kref);

}

EXPORT_SYMBOL_GPL(media_request_object_init);



int media_request_object_bind(struct media_request *req,

			      const struct media_request_object_ops *ops,

			      void *priv, bool is_buffer,

			      struct media_request_object *obj)

{

	unsigned long flags;

	int ret = -EBUSY;



	if (WARN_ON(!ops->release))

		return -EPERM;



	spin_lock_irqsave(&req->lock, flags);



	if (WARN_ON(req->state != MEDIA_REQUEST_STATE_UPDATING))

		goto unlock;



	obj->req = req;

	obj->ops = ops;

	obj->priv = priv;



	if (is_buffer)

		list_add_tail(&obj->list, &req->objects);

	else

		list_add(&obj->list, &req->objects);

	req->num_incomplete_objects++;

	ret = 0;



unlock:

	spin_unlock_irqrestore(&req->lock, flags);

	return ret;

}

EXPORT_SYMBOL_GPL(media_request_object_bind);



void media_request_object_unbind(struct media_request_object *obj)

{

	struct media_request *req = obj->req;

	unsigned long flags;

	bool completed = false;



	if (WARN_ON(!req))

		return;



	spin_lock_irqsave(&req->lock, flags);

	list_del(&obj->list);

	obj->req = NULL;



	if (req->state == MEDIA_REQUEST_STATE_COMPLETE)

		goto unlock;



	if (WARN_ON(req->state == MEDIA_REQUEST_STATE_VALIDATING))

		goto unlock;



	if (req->state == MEDIA_REQUEST_STATE_CLEANING) {

		if (!obj->completed)

			req->num_incomplete_objects--;

		goto unlock;

	}



	if (WARN_ON(!req->num_incomplete_objects))

		goto unlock;



	req->num_incomplete_objects--;

	if (req->state == MEDIA_REQUEST_STATE_QUEUED &&

	    !req->num_incomplete_objects) {

		req->state = MEDIA_REQUEST_STATE_COMPLETE;

		completed = true;

		wake_up_interruptible_all(&req->poll_wait);

	}



unlock:

	spin_unlock_irqrestore(&req->lock, flags);

	if (obj->ops->unbind)

		obj->ops->unbind(obj);

	if (completed)

		media_request_put(req);

}

EXPORT_SYMBOL_GPL(media_request_object_unbind);



void media_request_object_complete(struct media_request_object *obj)

{

	struct media_request *req = obj->req;

	unsigned long flags;

	bool completed = false;



	spin_lock_irqsave(&req->lock, flags);

	if (obj->completed)

		goto unlock;

	obj->completed = true;

	if (WARN_ON(!req->num_incomplete_objects) ||

	    WARN_ON(req->state != MEDIA_REQUEST_STATE_QUEUED))

		goto unlock;



	if (!--req->num_incomplete_objects) {

		req->state = MEDIA_REQUEST_STATE_COMPLETE;

		wake_up_interruptible_all(&req->poll_wait);

		completed = true;

	}

unlock:

	spin_unlock_irqrestore(&req->lock, flags);

	if (completed)

		media_request_put(req);

}

EXPORT_SYMBOL_GPL(media_request_object_complete);

include/media/media-device.h

+29 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 


struct ida;

struct device;

struct media_device;



/**

 * struct media_entity_notify - Media Entity Notify
@@ -50,10 +51,32 @@ struct media_entity_notify { 
 * struct media_device_ops - Media device operations

 * @link_notify: Link state change notification callback. This callback is

 *		 called with the graph_mutex held.

 * @req_alloc: Allocate a request. Set this if you need to allocate a struct

 *	       larger then struct media_request. @req_alloc and @req_free must

 *	       either both be set or both be NULL.

 * @req_free: Free a request. Set this if @req_alloc was set as well, leave

 *	      to NULL otherwise.

 * @req_validate: Validate a request, but do not queue yet. The req_queue_mutex

 *	          lock is held when this op is called.

 * @req_queue: Queue a validated request, cannot fail. If something goes

 *	       wrong when queueing this request then it should be marked

 *	       as such internally in the driver and any related buffers

 *	       must eventually return to vb2 with state VB2_BUF_STATE_ERROR.

 *	       The req_queue_mutex lock is held when this op is called.

 *	       It is important that vb2 buffer objects are queued last after

 *	       all other object types are queued: queueing a buffer kickstarts

 *	       the request processing, so all other objects related to the

 *	       request (and thus the buffer) must be available to the driver.

 *	       And once a buffer is queued, then the driver can complete

 *	       or delete objects from the request before req_queue exits.

 */

struct media_device_ops {

	int (*link_notify)(struct media_link *link, u32 flags,

			   unsigned int notification);

	struct media_request *(*req_alloc)(struct media_device *mdev);

	void (*req_free)(struct media_request *req);

	int (*req_validate)(struct media_request *req);

	void (*req_queue)(struct media_request *req);

};



/**
@@ -88,6 +111,9 @@ struct media_device_ops { 
 * @disable_source: Disable Source Handler function pointer

 *

 * @ops:	Operation handler callbacks

 * @req_queue_mutex: Serialise the MEDIA_REQUEST_IOC_QUEUE ioctl w.r.t.

 *		     other operations that stop or start streaming.

 * @request_id: Used to generate unique request IDs

 *

 * This structure represents an abstract high-level media device. It allows easy

 * access to entities and provides basic media device-level support. The
@@ -158,6 +184,9 @@ struct media_device { 
	void (*disable_source)(struct media_entity *entity);



	const struct media_device_ops *ops;



	struct mutex req_queue_mutex;

	atomic_t request_id;

};



/* We don't need to include pci.h or usb.h here */

include/media/media-request.h

0 → 100644
+334 −0

File added.

Preview size limit exceeded, changes collapsed.