Here is my review...
On Monday 29 March 2010 09:36:46 Pawel Osciak wrote:
> A mem-to-mem device is a device that uses memory buffers passed by
> userspace applications for both their source and destination data. This
> is different from existing drivers, which utilize memory buffers for either
> input or output, but not both.
>
> In terms of V4L2 such a device would be both of OUTPUT and CAPTURE type.
>
> Examples of such devices would be: image 'resizers', 'rotators',
> 'colorspace converters', etc.
>
> This patch adds a separate Kconfig sub-menu for mem-to-mem devices as well.
>
> Signed-off-by: Pawel Osciak <[email protected]>
> Signed-off-by: Marek Szyprowski <[email protected]>
> Reviewed-by: Kyungmin Park <[email protected]>
> ---
> drivers/media/video/Kconfig | 14 +
> drivers/media/video/Makefile | 2 +
> drivers/media/video/v4l2-mem2mem.c | 685
> ++++++++++++++++++++++++++++++++++++
> include/media/v4l2-mem2mem.h | 154 ++++++++
> 4 files changed, 855 insertions(+), 0 deletions(-)
> create mode 100644 drivers/media/video/v4l2-mem2mem.c
> create mode 100644 include/media/v4l2-mem2mem.h
>
> diff --git a/drivers/media/video/Kconfig b/drivers/media/video/Kconfig
> index f8fc865..5fd041e 100644
> --- a/drivers/media/video/Kconfig
> +++ b/drivers/media/video/Kconfig
> @@ -45,6 +45,10 @@ config VIDEO_TUNER
> tristate
> depends on MEDIA_TUNER
>
> +config V4L2_MEM2MEM_DEV
> + tristate
> + depends on VIDEOBUF_GEN
> +
> #
> # Multimedia Video device configuration
> #
> @@ -1107,3 +1111,13 @@ config USB_S2255
>
> endif # V4L_USB_DRIVERS
> endif # VIDEO_CAPTURE_DRIVERS
> +
> +menuconfig V4L_MEM2MEM_DRIVERS
> + bool "Memory-to-memory multimedia devices"
> + depends on VIDEO_V4L2
> + default n
> + ---help---
> + Say Y here to enable selecting drivers for V4L devices that
> + use system memory for both source and destination buffers, as opposed
> + to capture and output drivers, which use memory buffers for just
> + one of those.
> diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
> index b88b617..e974680 100644
> --- a/drivers/media/video/Makefile
> +++ b/drivers/media/video/Makefile
> @@ -117,6 +117,8 @@ obj-$(CONFIG_VIDEOBUF_VMALLOC) += videobuf-vmalloc.o
> obj-$(CONFIG_VIDEOBUF_DVB) += videobuf-dvb.o
> obj-$(CONFIG_VIDEO_BTCX) += btcx-risc.o
>
> +obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
> +
> obj-$(CONFIG_VIDEO_M32R_AR_M64278) += arv.o
>
> obj-$(CONFIG_VIDEO_CX2341X) += cx2341x.o
> diff --git a/drivers/media/video/v4l2-mem2mem.c
> b/drivers/media/video/v4l2-mem2mem.c
> new file mode 100644
> index 0000000..a78157f
> --- /dev/null
> +++ b/drivers/media/video/v4l2-mem2mem.c
> @@ -0,0 +1,685 @@
> +/*
> + * Memory-to-memory device framework for Video for Linux 2 and videobuf.
> + *
> + * Helper functions for devices that use videobuf buffers for both their
> + * source and destination.
> + *
> + * Copyright (c) 2009-2010 Samsung Electronics Co., Ltd.
> + * Pawel Osciak, <[email protected]>
> + * Marek Szyprowski, <[email protected]>
> + *
> + * 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; either version 2 of the License, or (at your
> + * option) any later version.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/sched.h>
> +#include <media/videobuf-core.h>
> +#include <media/v4l2-mem2mem.h>
> +
> +MODULE_DESCRIPTION("Mem to mem device framework for videobuf");
> +MODULE_AUTHOR("Pawel Osciak, <[email protected]>");
> +MODULE_LICENSE("GPL");
> +
> +static int debug;
> +module_param(debug, int, 0644);
> +
> +#define dprintk(fmt, arg...) \
> + do { \
> + if (debug >= 1) \
> + printk(KERN_DEBUG "%s: " fmt, __func__, ## arg);\
> + } while (0)
> +
> +
> +/* Instance is already queued on the jobqueue */
> +#define TRANS_QUEUED (1 << 0)
> +/* Instance is currently running in hardware */
> +#define TRANS_RUNNING (1 << 1)
> +
> +
> +/* Offset base for buffers on the destination queue - used to distinguish
> + * between source and destination buffers when mmapping - they receive the
> same
> + * offsets but for different queues */
> +#define DST_QUEUE_OFF_BASE (1 << 30)
> +
> +
> +/**
> + * struct v4l2_m2m_dev - per-device context
> + * @curr_ctx: currently running instance
> + * @jobqueue: instances queued to run
> + * @job_spinlock: protects jobqueue
> + * @m2m_ops: driver callbacks
> + */
> +struct v4l2_m2m_dev {
> + struct v4l2_m2m_ctx *curr_ctx;
> +
> + struct list_head jobqueue;
Using job_queue is a bit more consistent as you also use an '_' in job_spinlock.
> + spinlock_t job_spinlock;
> +
> + struct v4l2_m2m_ops *m2m_ops;
> +};
> +
> +static struct v4l2_m2m_queue_ctx *get_queue_ctx(struct v4l2_m2m_ctx *m2m_ctx,
> + enum v4l2_buf_type type)
> +{
> + switch (type) {
> + case V4L2_BUF_TYPE_VIDEO_CAPTURE:
> + return &m2m_ctx->cap_q_ctx;
> + case V4L2_BUF_TYPE_VIDEO_OUTPUT:
> + return &m2m_ctx->out_q_ctx;
> + default:
> + printk(KERN_ERR "Invalid buffer type\n");
> + return NULL;
> + }
> +}
> +
> +/**
> + * v4l2_m2m_get_vq() - return videobuf_queue for the given type
> + */
> +struct videobuf_queue *v4l2_m2m_get_vq(struct v4l2_m2m_ctx *m2m_ctx,
> + enum v4l2_buf_type type)
> +{
> + struct v4l2_m2m_queue_ctx *q_ctx;
> +
> + q_ctx = get_queue_ctx(m2m_ctx, type);
> + if (!q_ctx)
> + return NULL;
> +
> + return &q_ctx->q;
Shorter:
struct v4l2_m2m_queue_ctx *q_ctx = get_queue_ctx(m2m_ctx, type);
return q_ctx ? &q_ctx->q : NULL;
> +}
> +EXPORT_SYMBOL(v4l2_m2m_get_vq);
> +
> +/**
> + * v4l2_m2m_get_src_vq() - return videobuf_queue for source buffers
> + */
> +struct videobuf_queue *v4l2_m2m_get_src_vq(struct v4l2_m2m_ctx *m2m_ctx)
> +{
> + return v4l2_m2m_get_vq(m2m_ctx, V4L2_BUF_TYPE_VIDEO_OUTPUT);
> +}
> +EXPORT_SYMBOL(v4l2_m2m_get_src_vq);
> +
> +/**
> + * v4l2_m2m_get_dst_vq() - return videobuf_queue for destination buffers
> + */
> +struct videobuf_queue *v4l2_m2m_get_dst_vq(struct v4l2_m2m_ctx *m2m_ctx)
> +{
> + return v4l2_m2m_get_vq(m2m_ctx, V4L2_BUF_TYPE_VIDEO_CAPTURE);
> +}
> +EXPORT_SYMBOL(v4l2_m2m_get_dst_vq);
> +
> +/**
> + * v4l2_m2m_next_buf() - return next buffer from the list of ready buffers
> + */
> +static void *v4l2_m2m_next_buf(struct v4l2_m2m_ctx *m2m_ctx,
> + enum v4l2_buf_type type)
> +{
> + struct v4l2_m2m_queue_ctx *q_ctx;
> + struct videobuf_buffer *vb = NULL;
> + unsigned long flags;
> +
> + q_ctx = get_queue_ctx(m2m_ctx, type);
> + if (!q_ctx)
> + return NULL;
> +
> + spin_lock_irqsave(q_ctx->q.irqlock, flags);
> +
> + if (list_empty(&q_ctx->rdy_queue))
> + goto end;
> +
> + vb = list_entry(q_ctx->rdy_queue.next, struct videobuf_buffer, queue);
> + vb->state = VIDEOBUF_ACTIVE;
> +
> +end:
> + spin_unlock_irqrestore(q_ctx->q.irqlock, flags);
> + return vb;
> +}
> +
> +/**
> + * v4l2_m2m_next_src_buf() - return next source buffer from the list of ready
> + * buffers
> + */
> +inline void *v4l2_m2m_next_src_buf(struct v4l2_m2m_ctx *m2m_ctx)
inline makes no sense for an exported function.
You can also move this to the header and make it static inline. That would be
a valid option for a lot of these small one-liner functions.
> +{
> + return v4l2_m2m_next_buf(m2m_ctx, V4L2_BUF_TYPE_VIDEO_OUTPUT);
> +}
> +EXPORT_SYMBOL(v4l2_m2m_next_src_buf);
> +
> +/**
> + * v4l2_m2m_next_dst_buf() - return next destination buffer from the list of
> + * ready buffers
> + */
> +inline void *v4l2_m2m_next_dst_buf(struct v4l2_m2m_ctx *m2m_ctx)
> +{
> + return v4l2_m2m_next_buf(m2m_ctx, V4L2_BUF_TYPE_VIDEO_CAPTURE);
> +}
> +EXPORT_SYMBOL(v4l2_m2m_next_dst_buf);
> +
> +/**
> + * v4l2_m2m_buf_remove() - take off a buffer from the list of ready buffers
> and
> + * return it
> + */
> +static void *v4l2_m2m_buf_remove(struct v4l2_m2m_ctx *m2m_ctx,
> + enum v4l2_buf_type type)
> +{
> + struct v4l2_m2m_queue_ctx *q_ctx;
> + struct videobuf_buffer *vb = NULL;
> + unsigned long flags;
> +
> + q_ctx = get_queue_ctx(m2m_ctx, type);
> + if (!q_ctx)
> + return NULL;
> +
> + spin_lock_irqsave(q_ctx->q.irqlock, flags);
> + if (!list_empty(&q_ctx->rdy_queue)) {
> + vb = list_entry(q_ctx->rdy_queue.next, struct videobuf_buffer,
> + queue);
> + list_del(&vb->queue);
> + q_ctx->num_rdy--;
> + }
> + spin_unlock_irqrestore(q_ctx->q.irqlock, flags);
> +
> + return vb;
> +}
> +
> +/**
> + * v4l2_m2m_src_buf_remove() - take off a source buffer from the list of
> ready
> + * buffers and return it
> + */
> +void *v4l2_m2m_src_buf_remove(struct v4l2_m2m_ctx *m2m_ctx)
> +{
> + return v4l2_m2m_buf_remove(m2m_ctx, V4L2_BUF_TYPE_VIDEO_OUTPUT);
> +}
> +EXPORT_SYMBOL(v4l2_m2m_src_buf_remove);
> +
> +/**
> + * v4l2_m2m_dst_buf_remove() - take off a destination buffer from the list of
> + * ready buffers and return it
> + */
> +void *v4l2_m2m_dst_buf_remove(struct v4l2_m2m_ctx *m2m_ctx)
> +{
> + return v4l2_m2m_buf_remove(m2m_ctx, V4L2_BUF_TYPE_VIDEO_CAPTURE);
> +}
> +EXPORT_SYMBOL(v4l2_m2m_dst_buf_remove);
> +
> +
> +/*
> + * Scheduling handlers
> + */
> +
> +/**
> + * v4l2_m2m_get_curr_priv() - return driver private data for the currently
> + * running instance or NULL if no instance is running
> + */
> +void *v4l2_m2m_get_curr_priv(struct v4l2_m2m_dev *m2m_dev)
> +{
> + unsigned long flags;
> + void *ret;
> +
> + spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
> + if (!m2m_dev->curr_ctx)
> + ret = NULL;
> + else
> + ret = m2m_dev->curr_ctx->priv;
Shorter:
ret = m2m_dev->curr_ctx ? m2m_dev->curr_ctx->priv : NULL;
> + spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(v4l2_m2m_get_curr_priv);
> +
> +/**
> + * v4l2_m2m_try_run() - select next job to perform and run it if possible
> + *
> + * Get next transaction (if present) from the waiting jobs list and run it.
> + */
> +static void v4l2_m2m_try_run(struct v4l2_m2m_dev *m2m_dev)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
> + if (NULL != m2m_dev->curr_ctx) {
> + spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
> + dprintk("Another instance is running, won't run now\n");
> + return;
> + }
> +
> + if (list_empty(&m2m_dev->jobqueue)) {
> + spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
> + dprintk("No job pending\n");
> + return;
> + }
> +
> + m2m_dev->curr_ctx = list_entry(m2m_dev->jobqueue.next,
> + struct v4l2_m2m_ctx, queue);
> + m2m_dev->curr_ctx->job_flags |= TRANS_RUNNING;
> + spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
> +
> + m2m_dev->m2m_ops->device_run(m2m_dev->curr_ctx->priv);
> +
> + return;
Bogus return.
> +}
> +
> +/**
> + * v4l2_m2m_try_schedule() - check whether an instance is ready to be added
> to
> + * the pending job queue and add it if so.
> + * @m2m_ctx: m2m context assigned to the instance to be checked
> + *
> + * There are three basic requirements an instance has to meet to be able to
> run:
> + * 1) at least one source buffer has to be queued,
> + * 2) at least one destination buffer has to be queued,
> + * 3) streaming has to be on.
> + *
> + * There may also be additional, custom requirements. In such case the driver
> + * should supply a custom callback (job_ready in v4l2_m2m_ops) that should
> + * return 1 if the instance is ready.
> + * An example of the above could be an instance that requires more than one
> + * src/dst buffer per transaction.
> + */
> +static void v4l2_m2m_try_schedule(struct v4l2_m2m_ctx *m2m_ctx)
> +{
> + struct v4l2_m2m_dev *m2m_dev;
> + unsigned long flags_job, flags;
> +
> + m2m_dev = m2m_ctx->m2m_dev;
> + dprintk("Trying to schedule a job for m2m_ctx: %p\n", m2m_ctx);
> +
> + if (!m2m_ctx->out_q_ctx.q.streaming
> + || !m2m_ctx->cap_q_ctx.q.streaming) {
> + dprintk("Streaming needs to be on for both queues\n");
> + return;
> + }
> +
> + spin_lock_irqsave(&m2m_dev->job_spinlock, flags_job);
> + if (m2m_ctx->job_flags & TRANS_QUEUED) {
> + spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
> + dprintk("On job queue already\n");
> + return;
> + }
> +
> + spin_lock_irqsave(m2m_ctx->out_q_ctx.q.irqlock, flags);
Two spin_lock_irqsave's? I think it will work, but it is very unusual.
Does job_spinlock really have to be held with interrupts turned off?
> + if (list_empty(&m2m_ctx->out_q_ctx.rdy_queue)) {
> + spin_unlock_irqrestore(m2m_ctx->out_q_ctx.q.irqlock, flags);
> + spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
> + dprintk("No input buffers available\n");
> + return;
> + }
> + if (list_empty(&m2m_ctx->cap_q_ctx.rdy_queue)) {
> + spin_unlock_irqrestore(m2m_ctx->out_q_ctx.q.irqlock, flags);
> + spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
> + dprintk("No output buffers available\n");
> + return;
> + }
> + spin_unlock_irqrestore(m2m_ctx->out_q_ctx.q.irqlock, flags);
> +
> + if (m2m_dev->m2m_ops->job_ready
> + && (!m2m_dev->m2m_ops->job_ready(m2m_ctx->priv))) {
> + spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
> + dprintk("Driver not ready\n");
> + return;
> + }
> +
> + if (!(m2m_ctx->job_flags & TRANS_QUEUED)) {
> + list_add_tail(&m2m_ctx->queue, &m2m_dev->jobqueue);
> + m2m_ctx->job_flags |= TRANS_QUEUED;
> + }
> + spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
> +
> + v4l2_m2m_try_run(m2m_dev);
> +}
> +
> +/**
> + * v4l2_m2m_job_finish() - inform the framework that a job has been finished
> + * and have it clean up
> + *
> + * Called by a driver to yield back the device after it has finished with it.
> + * Should be called as soon as possible after reaching a state which allows
> + * other instances to take control of the device.
> + *
> + * This function has to be called only after device_run() callback has been
> + * called on the driver. To prevent recursion, it should not be called
> directly
> + * from the device_run() callback though.
> + */
> +void v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
> + struct v4l2_m2m_ctx *m2m_ctx)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
> + if (!m2m_dev->curr_ctx || m2m_dev->curr_ctx != m2m_ctx) {
> + spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
> + dprintk("Called by an instance not currently running\n");
> + return;
> + }
> +
> + list_del(&m2m_dev->curr_ctx->queue);
> + m2m_dev->curr_ctx->job_flags &= ~(TRANS_QUEUED | TRANS_RUNNING);
> + m2m_dev->curr_ctx = NULL;
> +
> + spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
> +
> + /* This instance might have more buffers ready, but since we do not
> + * allow more than one job on the jobqueue per instance, each has
> + * to be scheduled separately after the previous one finishes. */
> + v4l2_m2m_try_schedule(m2m_ctx);
> + v4l2_m2m_try_run(m2m_dev);
> +}
> +EXPORT_SYMBOL(v4l2_m2m_job_finish);
> +
> +/**
> + * v4l2_m2m_reqbufs() - multi-queue-aware REQBUFS multiplexer
> + */
> +int v4l2_m2m_reqbufs(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + struct v4l2_requestbuffers *reqbufs)
> +{
> + struct videobuf_queue *vq;
> +
> + vq = v4l2_m2m_get_vq(m2m_ctx, reqbufs->type);
> + return videobuf_reqbufs(vq, reqbufs);
> +}
> +EXPORT_SYMBOL_GPL(v4l2_m2m_reqbufs);
> +
> +/**
> + * v4l2_m2m_querybuf() - multi-queue-aware QUERYBUF multiplexer
> + *
> + * See v4l2_m2m_mmap() documentation for details.
> + */
> +int v4l2_m2m_querybuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + struct v4l2_buffer *buf)
> +{
> + struct videobuf_queue *vq;
> + int ret;
> +
> + vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
> + ret = videobuf_querybuf(vq, buf);
> +
> + if (buf->memory == V4L2_MEMORY_MMAP
> + && vq->type == V4L2_BUF_TYPE_VIDEO_CAPTURE) {
> + buf->m.offset += DST_QUEUE_OFF_BASE;
> + }
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_m2m_querybuf);
> +
> +/**
> + * v4l2_m2m_qbuf() - enqueue a source or destination buffer, depending on
> + * the type
> + */
> +int v4l2_m2m_qbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + struct v4l2_buffer *buf)
> +{
> + struct videobuf_queue *vq;
> + int ret;
> +
> + vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
> + ret = videobuf_qbuf(vq, buf);
> + if (ret)
> + return ret;
> +
> + v4l2_m2m_try_schedule(m2m_ctx);
> +
> + return 0;
Simplify:
ret = videobuf_qbuf(vq, buf);
if (!ret)
v4l2_m2m_try_schedule(m2m_ctx);
return ret;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_m2m_qbuf);
> +
> +/**
> + * v4l2_m2m_dqbuf() - dequeue a source or destination buffer, depending on
> + * the type
> + */
> +int v4l2_m2m_dqbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + struct v4l2_buffer *buf)
> +{
> + struct videobuf_queue *vq;
> +
> + vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
> + return videobuf_dqbuf(vq, buf, file->f_flags & O_NONBLOCK);
> +}
> +EXPORT_SYMBOL_GPL(v4l2_m2m_dqbuf);
> +
> +/**
> + * v4l2_m2m_streamon() - turn on streaming for a video queue
> + */
> +int v4l2_m2m_streamon(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + enum v4l2_buf_type type)
> +{
> + struct videobuf_queue *vq;
> + int ret;
> +
> + vq = v4l2_m2m_get_vq(m2m_ctx, type);
> + ret = videobuf_streamon(vq);
> + if (ret)
> + return ret;
> +
> + v4l2_m2m_try_schedule(m2m_ctx);
Same as above.
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_m2m_streamon);
> +
> +/**
> + * v4l2_m2m_streamoff() - turn off streaming for a video queue
> + */
> +int v4l2_m2m_streamoff(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + enum v4l2_buf_type type)
> +{
> + struct videobuf_queue *vq;
> +
> + vq = v4l2_m2m_get_vq(m2m_ctx, type);
> +
> + return videobuf_streamoff(vq);
Shorter:
return videobuf_streamoff(v4l2_m2m_get_vq(m2m_ctx, type));
> +}
> +EXPORT_SYMBOL_GPL(v4l2_m2m_streamoff);
> +
> +/**
> + * v4l2_m2m_poll() - poll replacement, for destination buffers only
> + *
> + * Call from driver's poll() function. Will poll the destination queue only.
> + */
> +unsigned int v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + struct poll_table_struct *wait)
> +{
> + struct videobuf_queue *dst_q;
> + struct videobuf_buffer *vb = NULL;
> + unsigned int rc = 0;
> +
> + dst_q = v4l2_m2m_get_dst_vq(m2m_ctx);
> +
> + mutex_lock(&dst_q->vb_lock);
> +
> + if (dst_q->streaming) {
> + if (!list_empty(&dst_q->stream))
> + vb = list_entry(dst_q->stream.next,
> + struct videobuf_buffer, stream);
> + }
> +
> + if (!vb)
> + rc = POLLERR;
> +
> + if (0 == rc) {
> + poll_wait(file, &vb->done, wait);
> + if (vb->state == VIDEOBUF_DONE || vb->state == VIDEOBUF_ERROR)
> + rc = POLLOUT | POLLRDNORM;
> + }
> +
> + mutex_unlock(&dst_q->vb_lock);
Would there be any need for polling for writing?
> + return rc;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_m2m_poll);
> +
> +/**
> + * v4l2_m2m_mmap() - source and destination queues-aware mmap multiplexer
> + *
> + * Call from driver's mmap() function. Will handle mmap() for both queues
> + * seamlessly for videobuffer, which will receive normal per-queue offsets
> and
> + * proper videobuf queue pointers. The differentiation is made outside
> videobuf
> + * by adding a predefined offset to buffers from one of the queues and
> + * subtracting it before passing it back to videobuf. Only drivers (and
> + * thus applications) receive modified offsets.
> + */
> +int v4l2_m2m_mmap(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + struct vm_area_struct *vma)
> +{
> + unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
> + struct videobuf_queue *vq;
> +
> + if (offset < DST_QUEUE_OFF_BASE) {
> + vq = v4l2_m2m_get_src_vq(m2m_ctx);
> + } else {
> + vq = v4l2_m2m_get_dst_vq(m2m_ctx);
> + vma->vm_pgoff -= (DST_QUEUE_OFF_BASE >> PAGE_SHIFT);
> + }
> +
> + return videobuf_mmap_mapper(vq, vma);
> +}
> +EXPORT_SYMBOL(v4l2_m2m_mmap);
> +
> +/**
> + * v4l2_m2m_init() - initialize per-driver m2m data
> + *
> + * Usually called from driver's probe() function.
> + */
> +struct v4l2_m2m_dev *v4l2_m2m_init(struct v4l2_m2m_ops *m2m_ops)
> +{
> + struct v4l2_m2m_dev *m2m_dev;
> +
> + if (!m2m_ops)
> + return ERR_PTR(-EINVAL);
> +
> + BUG_ON(!m2m_ops->device_run);
> + BUG_ON(!m2m_ops->job_abort);
No need to crash. Use WARN_ON and return an error.
Learned something today: I didn't know ERR_PTR existed! Nice.
> +
> + m2m_dev = kzalloc(sizeof *m2m_dev, GFP_KERNEL);
> + if (!m2m_dev)
> + return ERR_PTR(-ENOMEM);
> +
> + m2m_dev->curr_ctx = NULL;
> + m2m_dev->m2m_ops = m2m_ops;
> + INIT_LIST_HEAD(&m2m_dev->jobqueue);
> + spin_lock_init(&m2m_dev->job_spinlock);
> +
> + return m2m_dev;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_m2m_init);
> +
> +/**
> + * v4l2_m2m_release() - cleans up and frees a m2m_dev structure
> + *
> + * Usually called from driver's remove() function.
> + */
> +void v4l2_m2m_release(struct v4l2_m2m_dev *m2m_dev)
> +{
> + kfree(m2m_dev);
> +}
> +EXPORT_SYMBOL_GPL(v4l2_m2m_release);
Wouldn't it make sense to embed this struct in a filehandle structure?
Then there is no need to allocate anything, you just need an init function.
I like embedding structures: it's quite clean.
> +
> +/**
> + * v4l2_m2m_ctx_init() - allocate and initialize a m2m context
> + * @priv - driver's instance private data
> + * @m2m_dev - a previously initialized m2m_dev struct
> + * @vq_init - a callback for queue type-specific initialization function to
> be
> + * used for initializing videobuf_queues
> + *
> + * Usually called from driver's open() function.
> + */
> +struct v4l2_m2m_ctx *v4l2_m2m_ctx_init(void *priv, struct v4l2_m2m_dev
> *m2m_dev,
> + void (*vq_init)(void *priv, struct videobuf_queue *,
> + enum v4l2_buf_type))
> +{
> + struct v4l2_m2m_ctx *m2m_ctx;
> + struct v4l2_m2m_queue_ctx *out_q_ctx;
> + struct v4l2_m2m_queue_ctx *cap_q_ctx;
> +
> + if (!vq_init)
> + return ERR_PTR(-EINVAL);
> +
> + m2m_ctx = kzalloc(sizeof *m2m_ctx, GFP_KERNEL);
> + if (!m2m_ctx)
> + return ERR_PTR(-ENOMEM);
> +
> + m2m_ctx->priv = priv;
> + m2m_ctx->m2m_dev = m2m_dev;
> +
> + out_q_ctx = get_queue_ctx(m2m_ctx, V4L2_BUF_TYPE_VIDEO_OUTPUT);
> + cap_q_ctx = get_queue_ctx(m2m_ctx, V4L2_BUF_TYPE_VIDEO_CAPTURE);
> +
> + INIT_LIST_HEAD(&out_q_ctx->rdy_queue);
> + INIT_LIST_HEAD(&cap_q_ctx->rdy_queue);
> +
> + INIT_LIST_HEAD(&m2m_ctx->queue);
> +
> + vq_init(priv, &out_q_ctx->q, V4L2_BUF_TYPE_VIDEO_OUTPUT);
> + vq_init(priv, &cap_q_ctx->q, V4L2_BUF_TYPE_VIDEO_CAPTURE);
> + out_q_ctx->q.priv_data = cap_q_ctx->q.priv_data = priv;
> +
> + return m2m_ctx;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_m2m_ctx_init);
> +
> +/**
> + * v4l2_m2m_ctx_release() - release m2m context
> + *
> + * Usually called from driver's release() function.
> + */
> +void v4l2_m2m_ctx_release(struct v4l2_m2m_ctx *m2m_ctx)
> +{
> + struct v4l2_m2m_dev *m2m_dev;
> + struct videobuf_buffer *vb;
> + unsigned long flags;
> +
> + m2m_dev = m2m_ctx->m2m_dev;
> +
> + spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
> + if (m2m_ctx->job_flags & TRANS_RUNNING) {
> + spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
> + m2m_dev->m2m_ops->job_abort(m2m_ctx->priv);
> + dprintk("m2m_ctx %p running, will wait to complete", m2m_ctx);
> + vb = v4l2_m2m_next_dst_buf(m2m_ctx);
> + BUG_ON(NULL == vb);
> + wait_event(vb->done, vb->state != VIDEOBUF_ACTIVE
> + && vb->state != VIDEOBUF_QUEUED);
> + } else if (m2m_ctx->job_flags & TRANS_QUEUED) {
> + list_del(&m2m_ctx->queue);
> + m2m_ctx->job_flags &= ~(TRANS_QUEUED | TRANS_RUNNING);
> + spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
> + dprintk("m2m_ctx: %p had been on queue and was removed\n",
> + m2m_ctx);
> + } else {
> + /* Do nothing, was not on queue/running */
> + spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
> + }
> +
> + videobuf_stop(&m2m_ctx->cap_q_ctx.q);
> + videobuf_stop(&m2m_ctx->out_q_ctx.q);
> +
> + videobuf_mmap_free(&m2m_ctx->cap_q_ctx.q);
> + videobuf_mmap_free(&m2m_ctx->out_q_ctx.q);
> +
> + kfree(m2m_ctx);
> +}
> +EXPORT_SYMBOL_GPL(v4l2_m2m_ctx_release);
> +
> +/**
> + * v4l2_m2m_buf_queue() - add a buffer to the proper ready buffers list.
> + *
> + * Call from withing buf_queue() videobuf_queue_ops callback.
> + *
> + * Locking: Caller holds q->irqlock (taken by videobuf before calling
> buf_queue
> + * callback in the driver).
> + */
> +void v4l2_m2m_buf_queue(struct v4l2_m2m_ctx *m2m_ctx, struct videobuf_queue
> *vq,
> + struct videobuf_buffer *vb)
> +{
> + struct v4l2_m2m_queue_ctx *q_ctx;
> +
> + q_ctx = get_queue_ctx(m2m_ctx, vq->type);
> + if (!q_ctx)
> + return;
> +
> + list_add_tail(&vb->queue, &q_ctx->rdy_queue);
> + q_ctx->num_rdy++;
> +
> + vb->state = VIDEOBUF_QUEUED;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_m2m_buf_queue);
> +
> diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
> new file mode 100644
> index 0000000..33fe9f3
> --- /dev/null
> +++ b/include/media/v4l2-mem2mem.h
> @@ -0,0 +1,154 @@
> +/*
> + * Memory-to-memory device framework for Video for Linux 2.
> + *
> + * Helper functions for devices that use memory buffers for both source
> + * and destination.
> + *
> + * Copyright (c) 2009 Samsung Electronics Co., Ltd.
> + * Pawel Osciak, <[email protected]>
> + * Marek Szyprowski, <[email protected]>
> + *
> + * 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; either version 2 of the
> + * License, or (at your option) any later version
> + */
> +
> +#ifndef _MEDIA_V4L2_MEM2MEM_H
> +#define _MEDIA_V4L2_MEM2MEM_H
> +
> +#include <media/videobuf-core.h>
> +
> +/**
> + * struct v4l2_m2m_ops - mem-to-mem device driver callbacks
> + * @device_run: required. Begin the actual job (transaction) inside this
> + * callback.
> + * The job does NOT have to end before this callback returns
> + * (and it will be the usual case). When the job finishes,
> + * v4l2_m2m_job_finish() has to be called.
> + * @job_ready: optional. Should return 0 if the driver does not have a
> job
> + * fully prepared to run yet (i.e. it will not be able to finish a
> + * transaction without sleeping). If not provided, it will be
> + * assumed that one source and one destination buffer are all
> + * that is required for the driver to perform one full transaction.
> + * This method may not sleep.
> + * @job_abort: required. Informs the driver that it has to abort the
> currently
> + * running transaction as soon as possible (i.e. as soon as it can
> + * stop the device safely; e.g. in the next interrupt handler),
> + * even if the transaction would not have been finished by then.
> + * After the driver performs the necessary steps, it has to call
> + * v4l2_m2m_job_finish() (as if the transaction ended normally).
> + * This function does not have to (and will usually not) wait
> + * until the device enters a state when it can be stopped.
> + */
> +struct v4l2_m2m_ops {
> + void (*device_run)(void *priv);
> + int (*job_ready)(void *priv);
> + void (*job_abort)(void *priv);
> +};
> +
> +struct v4l2_m2m_dev;
> +
> +struct v4l2_m2m_queue_ctx {
> +/* private: internal use only */
> + struct videobuf_queue q;
> +
> + /* Base value for offsets of mmaped buffers on this queue */
> + unsigned long offset_base;
> +
> + /* Queue for buffers ready to be processed as soon as this
> + * instance receives access to the device */
> + struct list_head rdy_queue;
> + u8 num_rdy;
> +};
> +
> +struct v4l2_m2m_ctx {
> +/* private: internal use only */
> + struct v4l2_m2m_dev *m2m_dev;
> +
> + /* Capture (output to memory) queue context */
> + struct v4l2_m2m_queue_ctx cap_q_ctx;
> +
> + /* Output (input from memory) queue context */
> + struct v4l2_m2m_queue_ctx out_q_ctx;
> +
> + /* For device job queue */
> + struct list_head queue;
> + unsigned long job_flags;
> +
> + /* Instance private data */
> + void *priv;
> +};
> +
> +void *v4l2_m2m_get_curr_priv(struct v4l2_m2m_dev *m2m_dev);
> +
> +struct videobuf_queue *v4l2_m2m_get_src_vq(struct v4l2_m2m_ctx *m2m_ctx);
> +struct videobuf_queue *v4l2_m2m_get_dst_vq(struct v4l2_m2m_ctx *m2m_ctx);
> +struct videobuf_queue *v4l2_m2m_get_vq(struct v4l2_m2m_ctx *m2m_ctx,
> + enum v4l2_buf_type type);
> +
> +void v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
> + struct v4l2_m2m_ctx *m2m_ctx);
> +
> +void *v4l2_m2m_next_src_buf(struct v4l2_m2m_ctx *m2m_ctx);
> +void *v4l2_m2m_next_dst_buf(struct v4l2_m2m_ctx *m2m_ctx);
> +
> +void *v4l2_m2m_src_buf_remove(struct v4l2_m2m_ctx *m2m_ctx);
> +void *v4l2_m2m_dst_buf_remove(struct v4l2_m2m_ctx *m2m_ctx);
> +
> +
> +int v4l2_m2m_reqbufs(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + struct v4l2_requestbuffers *reqbufs);
> +
> +int v4l2_m2m_querybuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + struct v4l2_buffer *buf);
> +
> +int v4l2_m2m_qbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + struct v4l2_buffer *buf);
> +int v4l2_m2m_dqbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + struct v4l2_buffer *buf);
> +
> +int v4l2_m2m_streamon(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + enum v4l2_buf_type type);
> +int v4l2_m2m_streamoff(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + enum v4l2_buf_type type);
> +
> +unsigned int v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + struct poll_table_struct *wait);
> +
> +int v4l2_m2m_mmap(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> + struct vm_area_struct *vma);
> +
> +struct v4l2_m2m_dev *v4l2_m2m_init(struct v4l2_m2m_ops *m2m_ops);
> +void v4l2_m2m_release(struct v4l2_m2m_dev *m2m_dev);
> +
> +struct v4l2_m2m_ctx *v4l2_m2m_ctx_init(void *priv, struct v4l2_m2m_dev
> *m2m_dev,
> + void (*vq_init)(void *priv, struct videobuf_queue *,
> + enum v4l2_buf_type));
> +void v4l2_m2m_ctx_release(struct v4l2_m2m_ctx *m2m_ctx);
> +
> +void v4l2_m2m_buf_queue(struct v4l2_m2m_ctx *m2m_ctx, struct videobuf_queue
> *vq,
> + struct videobuf_buffer *vb);
> +
> +/**
> + * v4l2_m2m_num_src_bufs_ready() - return the number of source buffers ready
> for
> + * use
> + */
> +static inline
> +unsigned int v4l2_m2m_num_src_bufs_ready(struct v4l2_m2m_ctx *m2m_ctx)
> +{
> + return m2m_ctx->cap_q_ctx.num_rdy;
> +}
> +
> +/**
> + * v4l2_m2m_num_src_bufs_ready() - return the number of destination buffers
> + * ready for use
> + */
> +static inline
> +unsigned int v4l2_m2m_num_dst_bufs_ready(struct v4l2_m2m_ctx *m2m_ctx)
> +{
> + return m2m_ctx->out_q_ctx.num_rdy;
> +}
> +
> +#endif /* _MEDIA_V4L2_MEM2MEM_H */
> +
>
Regards,
Hans
--
Hans Verkuil - video4linux developer - sponsored by TANDBERG
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