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Commit 3415a89f authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab
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[media] vb2: add thread support 



In order to implement vb2 DVB support you need to be able to start
a kernel thread that queues and dequeues buffers, calling a callback
function for every buffer. This patch adds support for that.

It's based on drivers/media/v4l2-core/videobuf-dvb.c, but with all the DVB
specific stuff stripped out, thus making it much more generic.

Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Acked-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: default avatarMauro Carvalho Chehab <m.chehab@samsung.com>
parent 5f26f250

drivers/media/v4l2-core/videobuf2-core.c

+146 −0
Original line number Diff line number Diff line
@@ -6,6 +6,9 @@ 
 * Author: Pawel Osciak <pawel@osciak.com>

 *	   Marek Szyprowski <m.szyprowski@samsung.com>

 *

 * The vb2_thread implementation was based on code from videobuf-dvb.c:

 *	(c) 2004 Gerd Knorr <kraxel@bytesex.org> [SUSE Labs]

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation.
@@ -18,6 +21,8 @@ 
#include <linux/poll.h>

#include <linux/slab.h>

#include <linux/sched.h>

#include <linux/freezer.h>

#include <linux/kthread.h>



#include <media/v4l2-dev.h>

#include <media/v4l2-fh.h>
@@ -3005,6 +3010,147 @@ size_t vb2_write(struct vb2_queue *q, const char __user *data, size_t count, 
}

EXPORT_SYMBOL_GPL(vb2_write);



struct vb2_threadio_data {

	struct task_struct *thread;

	vb2_thread_fnc fnc;

	void *priv;

	bool stop;

};



static int vb2_thread(void *data)

{

	struct vb2_queue *q = data;

	struct vb2_threadio_data *threadio = q->threadio;

	struct vb2_fileio_data *fileio = q->fileio;

	bool set_timestamp = false;

	int prequeue = 0;

	int index = 0;

	int ret = 0;



	if (V4L2_TYPE_IS_OUTPUT(q->type)) {

		prequeue = q->num_buffers;

		set_timestamp =

			(q->timestamp_flags & V4L2_BUF_FLAG_TIMESTAMP_MASK) ==

			V4L2_BUF_FLAG_TIMESTAMP_COPY;

	}



	set_freezable();



	for (;;) {

		struct vb2_buffer *vb;



		/*

		 * Call vb2_dqbuf to get buffer back.

		 */

		memset(&fileio->b, 0, sizeof(fileio->b));

		fileio->b.type = q->type;

		fileio->b.memory = q->memory;

		if (prequeue) {

			fileio->b.index = index++;

			prequeue--;

		} else {

			call_void_qop(q, wait_finish, q);

			ret = vb2_internal_dqbuf(q, &fileio->b, 0);

			call_void_qop(q, wait_prepare, q);

			dprintk(5, "file io: vb2_dqbuf result: %d\n", ret);

		}

		if (threadio->stop)

			break;

		if (ret)

			break;

		try_to_freeze();



		vb = q->bufs[fileio->b.index];

		if (!(fileio->b.flags & V4L2_BUF_FLAG_ERROR))

			ret = threadio->fnc(vb, threadio->priv);

		if (ret)

			break;

		call_void_qop(q, wait_finish, q);

		if (set_timestamp)

			v4l2_get_timestamp(&fileio->b.timestamp);

		ret = vb2_internal_qbuf(q, &fileio->b);

		call_void_qop(q, wait_prepare, q);

		if (ret)

			break;

	}



	/* Hmm, linux becomes *very* unhappy without this ... */

	while (!kthread_should_stop()) {

		set_current_state(TASK_INTERRUPTIBLE);

		schedule();

	}

	return 0;

}



/*

 * This function should not be used for anything else but the videobuf2-dvb

 * support. If you think you have another good use-case for this, then please

 * contact the linux-media mailinglist first.

 */

int vb2_thread_start(struct vb2_queue *q, vb2_thread_fnc fnc, void *priv,

		     const char *thread_name)

{

	struct vb2_threadio_data *threadio;

	int ret = 0;



	if (q->threadio)

		return -EBUSY;

	if (vb2_is_busy(q))

		return -EBUSY;

	if (WARN_ON(q->fileio))

		return -EBUSY;



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

	if (threadio == NULL)

		return -ENOMEM;

	threadio->fnc = fnc;

	threadio->priv = priv;



	ret = __vb2_init_fileio(q, !V4L2_TYPE_IS_OUTPUT(q->type));

	dprintk(3, "file io: vb2_init_fileio result: %d\n", ret);

	if (ret)

		goto nomem;

	q->threadio = threadio;

	threadio->thread = kthread_run(vb2_thread, q, "vb2-%s", thread_name);

	if (IS_ERR(threadio->thread)) {

		ret = PTR_ERR(threadio->thread);

		threadio->thread = NULL;

		goto nothread;

	}

	return 0;



nothread:

	__vb2_cleanup_fileio(q);

nomem:

	kfree(threadio);

	return ret;

}

EXPORT_SYMBOL_GPL(vb2_thread_start);



int vb2_thread_stop(struct vb2_queue *q)

{

	struct vb2_threadio_data *threadio = q->threadio;

	struct vb2_fileio_data *fileio = q->fileio;

	int err;



	if (threadio == NULL)

		return 0;

	call_void_qop(q, wait_finish, q);

	threadio->stop = true;

	vb2_internal_streamoff(q, q->type);

	call_void_qop(q, wait_prepare, q);

	q->fileio = NULL;

	fileio->req.count = 0;

	vb2_reqbufs(q, &fileio->req);

	kfree(fileio);

	err = kthread_stop(threadio->thread);

	threadio->thread = NULL;

	kfree(threadio);

	q->fileio = NULL;

	q->threadio = NULL;

	return err;

}

EXPORT_SYMBOL_GPL(vb2_thread_stop);



/*

 * The following functions are not part of the vb2 core API, but are helper

include/media/videobuf2-core.h

+32 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 


struct vb2_alloc_ctx;

struct vb2_fileio_data;

struct vb2_threadio_data;



/**

 * struct vb2_mem_ops - memory handling/memory allocator operations
@@ -375,6 +376,7 @@ struct v4l2_fh; 
 * @start_streaming_called: start_streaming() was called successfully and we

 *		started streaming.

 * @fileio:	file io emulator internal data, used only if emulator is active

 * @threadio:	thread io internal data, used only if thread is active

 */

struct vb2_queue {

	enum v4l2_buf_type		type;
@@ -411,6 +413,7 @@ struct vb2_queue { 
	unsigned int			start_streaming_called:1;



	struct vb2_fileio_data		*fileio;

	struct vb2_threadio_data	*threadio;



#ifdef CONFIG_VIDEO_ADV_DEBUG

	/*
@@ -461,6 +464,35 @@ size_t vb2_read(struct vb2_queue *q, char __user *data, size_t count, 
		loff_t *ppos, int nonblock);

size_t vb2_write(struct vb2_queue *q, const char __user *data, size_t count,

		loff_t *ppos, int nonblock);

/**

 * vb2_thread_fnc - callback function for use with vb2_thread

 *

 * This is called whenever a buffer is dequeued in the thread.

 */

typedef int (*vb2_thread_fnc)(struct vb2_buffer *vb, void *priv);



/**

 * vb2_thread_start() - start a thread for the given queue.

 * @q:		videobuf queue

 * @fnc:	callback function

 * @priv:	priv pointer passed to the callback function

 * @thread_name:the name of the thread. This will be prefixed with "vb2-".

 *

 * This starts a thread that will queue and dequeue until an error occurs

 * or @vb2_thread_stop is called.

 *

 * This function should not be used for anything else but the videobuf2-dvb

 * support. If you think you have another good use-case for this, then please

 * contact the linux-media mailinglist first.

 */

int vb2_thread_start(struct vb2_queue *q, vb2_thread_fnc fnc, void *priv,

		     const char *thread_name);



/**

 * vb2_thread_stop() - stop the thread for the given queue.

 * @q:		videobuf queue

 */

int vb2_thread_stop(struct vb2_queue *q);



/**

 * vb2_is_streaming() - return streaming status of the queue