From: Hans Verkuil <hans.verkuil@xxxxxxxxx> In order to implement vb2 DVB or ALSA support you need to be able to start a kernel thread that queues and dequeues buffers, calling a callback function for every captured/displayed 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: Hans Verkuil <hans.verkuil@xxxxxxxxx> --- drivers/media/v4l2-core/videobuf2-core.c | 134 +++++++++++++++++++++++++++++++ include/media/videobuf2-core.h | 28 +++++++ 2 files changed, 162 insertions(+) diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c index 853d391..a86d033 100644 --- a/drivers/media/v4l2-core/videobuf2-core.c +++ b/drivers/media/v4l2-core/videobuf2-core.c @@ -6,6 +6,9 @@ * Author: Pawel Osciak <pawel@xxxxxxxxxx> * Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> * + * The vb2_thread implementation was based on code from videobuf-dvb.c: + * (c) 2004 Gerd Knorr <kraxel@xxxxxxxxxxx> [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> @@ -2508,6 +2513,135 @@ 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; + int prequeue = 0; + int index = 0; + int ret = 0; + + if (V4L2_TYPE_IS_OUTPUT(q->type)) + prequeue = q->num_buffers; + + 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_qop(q, wait_finish, q); + ret = vb2_internal_dqbuf(q, &fileio->b, 0); + call_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_qop(q, wait_finish, q); + ret = vb2_internal_qbuf(q, &fileio->b); + call_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; +} + +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_qop(q, wait_finish, q); + threadio->stop = true; + vb2_internal_streamoff(q, q->type); + call_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 diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h index 1be7f39..7dea795 100644 --- a/include/media/videobuf2-core.h +++ b/include/media/videobuf2-core.h @@ -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 @@ -330,6 +331,7 @@ struct v4l2_fh; * buffers queued. If set, then retry calling start_streaming when * queuing a new buffer. * @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; @@ -364,6 +366,7 @@ struct vb2_queue { unsigned int retry_start_streaming:1; struct vb2_fileio_data *fileio; + struct vb2_threadio_data *threadio; }; void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no); @@ -402,6 +405,31 @@ 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. + */ +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 -- 1.8.4.rc3 -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html