RE: [PATCH 4/5] usb: gadget/uvc: Port UVC webcam gadget to use videobuf2 framework

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Hi Laurent,

Can you please review this patch and let me know if any modifications
are required..

> -----Original Message-----
> From: Bhupesh SHARMA
> Sent: Friday, June 01, 2012 3:09 PM
> To: laurent.pinchart@xxxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx
> Cc: balbi@xxxxxx; linux-media@xxxxxxxxxxxxxxx;
> gregkh@xxxxxxxxxxxxxxxxxxx; Bhupesh SHARMA
> Subject: [PATCH 4/5] usb: gadget/uvc: Port UVC webcam gadget to use
> videobuf2 framework
>
> This patch reworks the videobuffer management logic present in the UVC
> webcam gadget and ports it to use the "more apt" videobuf2 framework
> for
> video buffer management.
>
> To support routing video data captured from a real V4L2 video capture
> device with a "zero copy" operation on videobuffers (as they pass from
> the V4L2
> domain to UVC domain via a user-space application), we need to support
> USER_PTR
> IO method at the UVC gadget side.
>
> So the V4L2 capture device driver can still continue to use MMAO IO
> method
> and now the user-space application can just pass a pointer to the video
> buffers
> being DeQueued from the V4L2 device side while Queueing them at the UVC
> gadget
> end. This ensures that we have a "zero-copy" design as the videobuffers
> pass
> from the V4L2 capture device to the UVC gadget.
>
> Note that there will still be a need to apply UVC specific payload
> headers
> on top of each UVC payload data, which will still require a copy
> operation
> to be performed in the 'encode' routines of the UVC gadget.
>
> Signed-off-by: Bhupesh Sharma <bhupesh.sharma@xxxxxx>
> ---
>  drivers/usb/gadget/Kconfig     |    1 +
>  drivers/usb/gadget/uvc_queue.c |  524 +++++++++++---------------------
> --------
>  drivers/usb/gadget/uvc_queue.h |   25 +--
>  drivers/usb/gadget/uvc_v4l2.c  |   35 ++--
>  drivers/usb/gadget/uvc_video.c |   17 +-
>  5 files changed, 184 insertions(+), 418 deletions(-)
>
> diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
> index 1f93861..5a351f8 100644
> --- a/drivers/usb/gadget/Kconfig
> +++ b/drivers/usb/gadget/Kconfig
> @@ -967,6 +967,7 @@ endif
>  config USB_G_WEBCAM
>       tristate "USB Webcam Gadget"
>       depends on VIDEO_DEV
> +     select VIDEOBUF2_VMALLOC
>       help
>         The Webcam Gadget acts as a composite USB Audio and Video Class
>         device. It provides a userspace API to process UVC control
> requests
> diff --git a/drivers/usb/gadget/uvc_queue.c
> b/drivers/usb/gadget/uvc_queue.c
> index 0cdf89d..907ece8 100644
> --- a/drivers/usb/gadget/uvc_queue.c
> +++ b/drivers/usb/gadget/uvc_queue.c
> @@ -10,6 +10,7 @@
>   *   (at your option) any later version.
>   */
>
> +#include <linux/atomic.h>
>  #include <linux/kernel.h>
>  #include <linux/mm.h>
>  #include <linux/list.h>
> @@ -18,7 +19,8 @@
>  #include <linux/videodev2.h>
>  #include <linux/vmalloc.h>
>  #include <linux/wait.h>
> -#include <linux/atomic.h>
> +
> +#include <media/videobuf2-vmalloc.h>
>
>  #include "uvc.h"
>
> @@ -28,271 +30,156 @@
>   * Video queues is initialized by uvc_queue_init(). The function
> performs
>   * basic initialization of the uvc_video_queue struct and never fails.
>   *
> - * Video buffer allocation and freeing are performed by
> uvc_alloc_buffers and
> - * uvc_free_buffers respectively. The former acquires the video queue
> lock,
> - * while the later must be called with the lock held (so that
> allocation can
> - * free previously allocated buffers). Trying to free buffers that are
> mapped
> - * to user space will return -EBUSY.
> - *
> - * Video buffers are managed using two queues. However, unlike most
> USB video
> - * drivers that use an in queue and an out queue, we use a main queue
> to hold
> - * all queued buffers (both 'empty' and 'done' buffers), and an irq
> queue to
> - * hold empty buffers. This design (copied from video-buf) minimizes
> locking
> - * in interrupt, as only one queue is shared between interrupt and
> user
> - * contexts.
> - *
> - * Use cases
> - * ---------
> - *
> - * Unless stated otherwise, all operations that modify the irq buffers
> queue
> - * are protected by the irq spinlock.
> - *
> - * 1. The user queues the buffers, starts streaming and dequeues a
> buffer.
> - *
> - *    The buffers are added to the main and irq queues. Both
> operations are
> - *    protected by the queue lock, and the later is protected by the
> irq
> - *    spinlock as well.
> - *
> - *    The completion handler fetches a buffer from the irq queue and
> fills it
> - *    with video data. If no buffer is available (irq queue empty),
> the handler
> - *    returns immediately.
> - *
> - *    When the buffer is full, the completion handler removes it from
> the irq
> - *    queue, marks it as ready (UVC_BUF_STATE_DONE) and wakes its wait
> queue.
> - *    At that point, any process waiting on the buffer will be woken
> up. If a
> - *    process tries to dequeue a buffer after it has been marked
> ready, the
> - *    dequeing will succeed immediately.
> - *
> - * 2. Buffers are queued, user is waiting on a buffer and the device
> gets
> - *    disconnected.
> - *
> - *    When the device is disconnected, the kernel calls the completion
> handler
> - *    with an appropriate status code. The handler marks all buffers
> in the
> - *    irq queue as being erroneous (UVC_BUF_STATE_ERROR) and wakes
> them up so
> - *    that any process waiting on a buffer gets woken up.
> - *
> - *    Waking up up the first buffer on the irq list is not enough, as
> the
> - *    process waiting on the buffer might restart the dequeue
> operation
> - *    immediately.
> - *
> + * Video buffers are managed by videobuf2. The driver uses a mutex to
> protect
> + * the videobuf2 queue operations by serializing calls to videobuf2
> and a
> + * spinlock to protect the IRQ queue that holds the buffers to be
> processed by
> + * the driver.
>   */
>
> -static void
> -uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> -{
> -     mutex_init(&queue->mutex);
> -     spin_lock_init(&queue->irqlock);
> -     INIT_LIST_HEAD(&queue->mainqueue);
> -     INIT_LIST_HEAD(&queue->irqqueue);
> -     queue->type = type;
> -}
> -
> -/*
> - * Free the video buffers.
> - *
> - * This function must be called with the queue lock held.
> +/* -------------------------------------------------------------------
> ----------
> + * videobuf2 queue operations
>   */
> -static int uvc_free_buffers(struct uvc_video_queue *queue)
> +
> +static int uvc_queue_setup(struct vb2_queue *vq, const struct
> v4l2_format *fmt,
> +                             unsigned int *nbuffers, unsigned int *nplanes,
> +                             unsigned int sizes[], void *alloc_ctxs[])
>  {
> -     unsigned int i;
> +     struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
> +     struct uvc_video *video =
> +                     container_of(queue, struct uvc_video, queue);
>
> -     for (i = 0; i < queue->count; ++i) {
> -             if (queue->buffer[i].vma_use_count != 0)
> -                     return -EBUSY;
> -     }
> +     if (*nbuffers > UVC_MAX_VIDEO_BUFFERS)
> +             *nbuffers = UVC_MAX_VIDEO_BUFFERS;
>
> -     if (queue->count) {
> -             vfree(queue->mem);
> -             queue->count = 0;
> -     }
> +     *nplanes = 1;
> +
> +     sizes[0] = video->imagesize;
>
>       return 0;
>  }
>
> -/*
> - * Allocate the video buffers.
> - *
> - * Pages are reserved to make sure they will not be swapped, as they
> will be
> - * filled in the URB completion handler.
> - *
> - * Buffers will be individually mapped, so they must all be page
> aligned.
> - */
> -static int
> -uvc_alloc_buffers(struct uvc_video_queue *queue, unsigned int
> nbuffers,
> -               unsigned int buflength)
> +static int uvc_buffer_prepare(struct vb2_buffer *vb)
>  {
> -     unsigned int bufsize = PAGE_ALIGN(buflength);
> -     unsigned int i;
> -     void *mem = NULL;
> -     int ret;
> +     struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
> +     struct uvc_buffer *buf = container_of(vb, struct uvc_buffer,
> buf);
>
> -     if (nbuffers > UVC_MAX_VIDEO_BUFFERS)
> -             nbuffers = UVC_MAX_VIDEO_BUFFERS;
> +     if (vb->v4l2_buf.type == V4L2_BUF_TYPE_VIDEO_OUTPUT &&
> +                     vb2_get_plane_payload(vb, 0) > vb2_plane_size(vb, 0))
> {
> +             uvc_trace(UVC_TRACE_CAPTURE, "[E] Bytes used out of
> bounds.\n");
> +             return -EINVAL;
> +     }
>
> -     mutex_lock(&queue->mutex);
> +     if (unlikely(queue->flags & UVC_QUEUE_DISCONNECTED))
> +             return -ENODEV;
>
> -     if ((ret = uvc_free_buffers(queue)) < 0)
> -             goto done;
> +     buf->state = UVC_BUF_STATE_QUEUED;
> +     buf->mem = vb2_plane_vaddr(vb, 0);
> +     buf->length = vb2_plane_size(vb, 0);
> +     if (vb->v4l2_buf.type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
> +             buf->bytesused = 0;
> +     else
> +             buf->bytesused = vb2_get_plane_payload(vb, 0);
>
> -     /* Bail out if no buffers should be allocated. */
> -     if (nbuffers == 0)
> -             goto done;
> +     return 0;
> +}
>
> -     /* Decrement the number of buffers until allocation succeeds. */
> -     for (; nbuffers > 0; --nbuffers) {
> -             mem = vmalloc_32(nbuffers * bufsize);
> -             if (mem != NULL)
> -                     break;
> -     }
> +static void uvc_buffer_queue(struct vb2_buffer *vb)
> +{
> +     struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
> +     struct uvc_buffer *buf = container_of(vb, struct uvc_buffer,
> buf);
> +     unsigned long flags;
>
> -     if (mem == NULL) {
> -             ret = -ENOMEM;
> -             goto done;
> -     }
> +     spin_lock_irqsave(&queue->irqlock, flags);
>
> -     for (i = 0; i < nbuffers; ++i) {
> -             memset(&queue->buffer[i], 0, sizeof queue->buffer[i]);
> -             queue->buffer[i].buf.index = i;
> -             queue->buffer[i].buf.m.offset = i * bufsize;
> -             queue->buffer[i].buf.length = buflength;
> -             queue->buffer[i].buf.type = queue->type;
> -             queue->buffer[i].buf.sequence = 0;
> -             queue->buffer[i].buf.field = V4L2_FIELD_NONE;
> -             queue->buffer[i].buf.memory = V4L2_MEMORY_MMAP;
> -             queue->buffer[i].buf.flags = 0;
> -             init_waitqueue_head(&queue->buffer[i].wait);
> +     if (likely(!(queue->flags & UVC_QUEUE_DISCONNECTED))) {
> +             list_add_tail(&buf->queue, &queue->irqqueue);
> +     } else {
> +             /* If the device is disconnected return the buffer to
> userspace
> +              * directly. The next QBUF call will fail with -ENODEV.
> +              */
> +             buf->state = UVC_BUF_STATE_ERROR;
> +             vb2_buffer_done(&buf->buf, VB2_BUF_STATE_ERROR);
>       }
>
> -     queue->mem = mem;
> -     queue->count = nbuffers;
> -     queue->buf_size = bufsize;
> -     ret = nbuffers;
> -
> -done:
> -     mutex_unlock(&queue->mutex);
> -     return ret;
> +     spin_unlock_irqrestore(&queue->irqlock, flags);
>  }
>
> -static void __uvc_query_buffer(struct uvc_buffer *buf,
> -             struct v4l2_buffer *v4l2_buf)
> +static struct vb2_ops uvc_queue_qops = {
> +     .queue_setup = uvc_queue_setup,
> +     .buf_prepare = uvc_buffer_prepare,
> +     .buf_queue = uvc_buffer_queue,
> +};
> +
> +static
> +void uvc_queue_init(struct uvc_video_queue *queue,
> +                             enum v4l2_buf_type type)
>  {
> -     memcpy(v4l2_buf, &buf->buf, sizeof *v4l2_buf);
> -
> -     if (buf->vma_use_count)
> -             v4l2_buf->flags |= V4L2_BUF_FLAG_MAPPED;
> -
> -     switch (buf->state) {
> -     case UVC_BUF_STATE_ERROR:
> -     case UVC_BUF_STATE_DONE:
> -             v4l2_buf->flags |= V4L2_BUF_FLAG_DONE;
> -             break;
> -     case UVC_BUF_STATE_QUEUED:
> -     case UVC_BUF_STATE_ACTIVE:
> -             v4l2_buf->flags |= V4L2_BUF_FLAG_QUEUED;
> -             break;
> -     case UVC_BUF_STATE_IDLE:
> -     default:
> -             break;
> -     }
> +     mutex_init(&queue->mutex);
> +     spin_lock_init(&queue->irqlock);
> +     INIT_LIST_HEAD(&queue->irqqueue);
> +     queue->queue.type = type;
> +     queue->queue.io_modes = VB2_MMAP | VB2_USERPTR;
> +     queue->queue.drv_priv = queue;
> +     queue->queue.buf_struct_size = sizeof(struct uvc_buffer);
> +     queue->queue.ops = &uvc_queue_qops;
> +     queue->queue.mem_ops = &vb2_vmalloc_memops;
> +     vb2_queue_init(&queue->queue);
>  }
>
> -static int
> -uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer
> *v4l2_buf)
> +/*
> + * Free the video buffers.
> + */
> +static void uvc_free_buffers(struct uvc_video_queue *queue)
>  {
> -     int ret = 0;
> -
>       mutex_lock(&queue->mutex);
> -     if (v4l2_buf->index >= queue->count) {
> -             ret = -EINVAL;
> -             goto done;
> -     }
> -
> -     __uvc_query_buffer(&queue->buffer[v4l2_buf->index], v4l2_buf);
> -
> -done:
> +     vb2_queue_release(&queue->queue);
>       mutex_unlock(&queue->mutex);
> -     return ret;
>  }
>
>  /*
> - * Queue a video buffer. Attempting to queue a buffer that has already
> been
> - * queued will return -EINVAL.
> + * Allocate the video buffers.
>   */
> -static int
> -uvc_queue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer
> *v4l2_buf)
> +static int uvc_alloc_buffers(struct uvc_video_queue *queue,
> +                             struct v4l2_requestbuffers *rb)
>  {
> -     struct uvc_buffer *buf;
> -     unsigned long flags;
> -     int ret = 0;
> -
> -     uvc_trace(UVC_TRACE_CAPTURE, "Queuing buffer %u.\n", v4l2_buf-
> >index);
> +     int ret;
>
> -     if (v4l2_buf->type != queue->type ||
> -         v4l2_buf->memory != V4L2_MEMORY_MMAP) {
> -             uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer type (%u)
> "
> -                     "and/or memory (%u).\n", v4l2_buf->type,
> -                     v4l2_buf->memory);
> -             return -EINVAL;
> -     }
> +     /*
> +      * we can support a max of UVC_MAX_VIDEO_BUFFERS video buffers
> +      */
> +     if (rb->count > UVC_MAX_VIDEO_BUFFERS)
> +             rb->count = UVC_MAX_VIDEO_BUFFERS;
>
>       mutex_lock(&queue->mutex);
> -     if (v4l2_buf->index >= queue->count) {
> -             uvc_trace(UVC_TRACE_CAPTURE, "[E] Out of range index.\n");
> -             ret = -EINVAL;
> -             goto done;
> -     }
> -
> -     buf = &queue->buffer[v4l2_buf->index];
> -     if (buf->state != UVC_BUF_STATE_IDLE) {
> -             uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer state "
> -                     "(%u).\n", buf->state);
> -             ret = -EINVAL;
> -             goto done;
> -     }
> -
> -     if (v4l2_buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT &&
> -         v4l2_buf->bytesused > buf->buf.length) {
> -             uvc_trace(UVC_TRACE_CAPTURE, "[E] Bytes used out of
> bounds.\n");
> -             ret = -EINVAL;
> -             goto done;
> -     }
> -
> -     if (v4l2_buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
> -             buf->buf.bytesused = 0;
> -     else
> -             buf->buf.bytesused = v4l2_buf->bytesused;
> -
> -     spin_lock_irqsave(&queue->irqlock, flags);
> -     if (queue->flags & UVC_QUEUE_DISCONNECTED) {
> -             spin_unlock_irqrestore(&queue->irqlock, flags);
> -             ret = -ENODEV;
> -             goto done;
> -     }
> -     buf->state = UVC_BUF_STATE_QUEUED;
> +     ret = vb2_reqbufs(&queue->queue, rb);
> +     mutex_unlock(&queue->mutex);
>
> -     ret = (queue->flags & UVC_QUEUE_PAUSED) != 0;
> -     queue->flags &= ~UVC_QUEUE_PAUSED;
> +     return ret ? ret : rb->count;
> +}
>
> -     list_add_tail(&buf->stream, &queue->mainqueue);
> -     list_add_tail(&buf->queue, &queue->irqqueue);
> -     spin_unlock_irqrestore(&queue->irqlock, flags);
> +static int uvc_query_buffer(struct uvc_video_queue *queue,
> +             struct v4l2_buffer *buf)
> +{
> +     int ret;
>
> -done:
> +     mutex_lock(&queue->mutex);
> +     ret = vb2_querybuf(&queue->queue, buf);
>       mutex_unlock(&queue->mutex);
> +
>       return ret;
>  }
>
> -static int uvc_queue_waiton(struct uvc_buffer *buf, int nonblocking)
> +static int
> +uvc_queue_buffer(struct uvc_video_queue *queue,
> +             struct v4l2_buffer *buf)
>  {
> -     if (nonblocking) {
> -             return (buf->state != UVC_BUF_STATE_QUEUED &&
> -                     buf->state != UVC_BUF_STATE_ACTIVE)
> -                     ? 0 : -EAGAIN;
> -     }
> +     int ret;
> +
> +     mutex_lock(&queue->mutex);
> +     ret = vb2_qbuf(&queue->queue, buf);
> +     mutex_unlock(&queue->mutex);
>
> -     return wait_event_interruptible(buf->wait,
> -             buf->state != UVC_BUF_STATE_QUEUED &&
> -             buf->state != UVC_BUF_STATE_ACTIVE);
> +     return ret;
>  }
>
>  /*
> @@ -300,58 +187,15 @@ static int uvc_queue_waiton(struct uvc_buffer
> *buf, int nonblocking)
>   * available.
>   */
>  static int
> -uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer
> *v4l2_buf,
> -                int nonblocking)
> +uvc_dequeue_buffer(struct uvc_video_queue *queue,
> +             struct v4l2_buffer *buf, int nonblocking)
>  {
> -     struct uvc_buffer *buf;
> -     int ret = 0;
> -
> -     if (v4l2_buf->type != queue->type ||
> -         v4l2_buf->memory != V4L2_MEMORY_MMAP) {
> -             uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer type (%u)
> "
> -                     "and/or memory (%u).\n", v4l2_buf->type,
> -                     v4l2_buf->memory);
> -             return -EINVAL;
> -     }
> +     int ret;
>
>       mutex_lock(&queue->mutex);
> -     if (list_empty(&queue->mainqueue)) {
> -             uvc_trace(UVC_TRACE_CAPTURE, "[E] Empty buffer queue.\n");
> -             ret = -EINVAL;
> -             goto done;
> -     }
> -
> -     buf = list_first_entry(&queue->mainqueue, struct uvc_buffer,
> stream);
> -     if ((ret = uvc_queue_waiton(buf, nonblocking)) < 0)
> -             goto done;
> -
> -     uvc_trace(UVC_TRACE_CAPTURE, "Dequeuing buffer %u (%u, %u
> bytes).\n",
> -             buf->buf.index, buf->state, buf->buf.bytesused);
> -
> -     switch (buf->state) {
> -     case UVC_BUF_STATE_ERROR:
> -             uvc_trace(UVC_TRACE_CAPTURE, "[W] Corrupted data "
> -                     "(transmission error).\n");
> -             ret = -EIO;
> -     case UVC_BUF_STATE_DONE:
> -             buf->state = UVC_BUF_STATE_IDLE;
> -             break;
> -
> -     case UVC_BUF_STATE_IDLE:
> -     case UVC_BUF_STATE_QUEUED:
> -     case UVC_BUF_STATE_ACTIVE:
> -     default:
> -             uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer state %u "
> -                     "(driver bug?).\n", buf->state);
> -             ret = -EINVAL;
> -             goto done;
> -     }
> -
> -     list_del(&buf->stream);
> -     __uvc_query_buffer(buf, v4l2_buf);
> -
> -done:
> +     ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
>       mutex_unlock(&queue->mutex);
> +
>       return ret;
>  }
>
> @@ -362,102 +206,27 @@ done:
>   * the device poll handler.
>   */
>  static unsigned int
> -uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> -            poll_table *wait)
> +uvc_queue_poll(struct uvc_video_queue *queue,
> +                     struct file *file, poll_table *wait)
>  {
> -     struct uvc_buffer *buf;
> -     unsigned int mask = 0;
> +     unsigned int ret;
>
>       mutex_lock(&queue->mutex);
> -     if (list_empty(&queue->mainqueue))
> -             goto done;
> -
> -     buf = list_first_entry(&queue->mainqueue, struct uvc_buffer,
> stream);
> -
> -     poll_wait(file, &buf->wait, wait);
> -     if (buf->state == UVC_BUF_STATE_DONE ||
> -         buf->state == UVC_BUF_STATE_ERROR)
> -             mask |= POLLOUT | POLLWRNORM;
> -
> -done:
> +     ret = vb2_poll(&queue->queue, file, wait);
>       mutex_unlock(&queue->mutex);
> -     return mask;
> -}
>
> -/*
> - * VMA operations.
> - */
> -static void uvc_vm_open(struct vm_area_struct *vma)
> -{
> -     struct uvc_buffer *buffer = vma->vm_private_data;
> -     buffer->vma_use_count++;
> +     return ret;
>  }
>
> -static void uvc_vm_close(struct vm_area_struct *vma)
> +static int uvc_queue_mmap(struct uvc_video_queue *queue,
> +                             struct vm_area_struct *vma)
>  {
> -     struct uvc_buffer *buffer = vma->vm_private_data;
> -     buffer->vma_use_count--;
> -}
> -
> -static struct vm_operations_struct uvc_vm_ops = {
> -     .open           = uvc_vm_open,
> -     .close          = uvc_vm_close,
> -};
> -
> -/*
> - * Memory-map a buffer.
> - *
> - * This function implements video buffer memory mapping and is
> intended to be
> - * used by the device mmap handler.
> - */
> -static int
> -uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct
> *vma)
> -{
> -     struct uvc_buffer *uninitialized_var(buffer);
> -     struct page *page;
> -     unsigned long addr, start, size;
> -     unsigned int i;
> -     int ret = 0;
> -
> -     start = vma->vm_start;
> -     size = vma->vm_end - vma->vm_start;
> +     int ret;
>
>       mutex_lock(&queue->mutex);
> -
> -     for (i = 0; i < queue->count; ++i) {
> -             buffer = &queue->buffer[i];
> -             if ((buffer->buf.m.offset >> PAGE_SHIFT) == vma->vm_pgoff)
> -                     break;
> -     }
> -
> -     if (i == queue->count || size != queue->buf_size) {
> -             ret = -EINVAL;
> -             goto done;
> -     }
> -
> -     /*
> -      * VM_IO marks the area as being an mmaped region for I/O to a
> -      * device. It also prevents the region from being core dumped.
> -      */
> -     vma->vm_flags |= VM_IO;
> -
> -     addr = (unsigned long)queue->mem + buffer->buf.m.offset;
> -     while (size > 0) {
> -             page = vmalloc_to_page((void *)addr);
> -             if ((ret = vm_insert_page(vma, start, page)) < 0)
> -                     goto done;
> -
> -             start += PAGE_SIZE;
> -             addr += PAGE_SIZE;
> -             size -= PAGE_SIZE;
> -     }
> -
> -     vma->vm_ops = &uvc_vm_ops;
> -     vma->vm_private_data = buffer;
> -     uvc_vm_open(vma);
> -
> -done:
> +     ret = vb2_mmap(&queue->queue, vma);
>       mutex_unlock(&queue->mutex);
> +
>       return ret;
>  }
>
> @@ -481,10 +250,10 @@ static void uvc_queue_cancel(struct
> uvc_video_queue *queue, int disconnect)
>       spin_lock_irqsave(&queue->irqlock, flags);
>       while (!list_empty(&queue->irqqueue)) {
>               buf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
> -                                    queue);
> +                                     queue);
>               list_del(&buf->queue);
>               buf->state = UVC_BUF_STATE_ERROR;
> -             wake_up(&buf->wait);
> +             vb2_buffer_done(&buf->buf, VB2_BUF_STATE_ERROR);
>       }
>       /* This must be protected by the irqlock spinlock to avoid race
>        * conditions between uvc_queue_buffer and the disconnection
> event that
> @@ -516,26 +285,28 @@ static void uvc_queue_cancel(struct
> uvc_video_queue *queue, int disconnect)
>   */
>  static int uvc_queue_enable(struct uvc_video_queue *queue, int enable)
>  {
> -     unsigned int i;
> +     unsigned long flags;
>       int ret = 0;
>
>       mutex_lock(&queue->mutex);
>       if (enable) {
> -             if (uvc_queue_streaming(queue)) {
> -                     ret = -EBUSY;
> +             ret = vb2_streamon(&queue->queue, queue->queue.type);
> +             if (ret < 0)
>                       goto done;
> -             }
> -             queue->sequence = 0;
> -             queue->flags |= UVC_QUEUE_STREAMING;
> +
>               queue->buf_used = 0;
> +             queue->flags |= UVC_QUEUE_STREAMING;
>       } else {
> -             uvc_queue_cancel(queue, 0);
> -             INIT_LIST_HEAD(&queue->mainqueue);
> -
> -             for (i = 0; i < queue->count; ++i)
> -                     queue->buffer[i].state = UVC_BUF_STATE_IDLE;
> -
> -             queue->flags &= ~UVC_QUEUE_STREAMING;
> +             if (uvc_queue_streaming(queue)) {
> +                     ret = vb2_streamoff(&queue->queue, queue-
> >queue.type);
> +                     if (ret < 0)
> +                             goto done;
> +
> +                     spin_lock_irqsave(&queue->irqlock, flags);
> +                     INIT_LIST_HEAD(&queue->irqqueue);
> +                     queue->flags &= ~UVC_QUEUE_STREAMING;
> +                     spin_unlock_irqrestore(&queue->irqlock, flags);
> +             }
>       }
>
>  done:
> @@ -543,30 +314,29 @@ done:
>       return ret;
>  }
>
> -/* called with queue->irqlock held.. */
> +/* called with &queue_irqlock held.. */
>  static struct uvc_buffer *
>  uvc_queue_next_buffer(struct uvc_video_queue *queue, struct uvc_buffer
> *buf)
>  {
>       struct uvc_buffer *nextbuf;
>
>       if ((queue->flags & UVC_QUEUE_DROP_INCOMPLETE) &&
> -         buf->buf.length != buf->buf.bytesused) {
> +                     buf->length != buf->bytesused) {
>               buf->state = UVC_BUF_STATE_QUEUED;
> -             buf->buf.bytesused = 0;
> +             vb2_set_plane_payload(&buf->buf, 0, 0);
>               return buf;
>       }
>
>       list_del(&buf->queue);
>       if (!list_empty(&queue->irqqueue))
>               nextbuf = list_first_entry(&queue->irqqueue, struct
> uvc_buffer,
> -                                        queue);
> +                                             queue);
>       else
>               nextbuf = NULL;
>
> -     buf->buf.sequence = queue->sequence++;
> -     do_gettimeofday(&buf->buf.timestamp);
> +     vb2_set_plane_payload(&buf->buf, 0, buf->bytesused);
> +     vb2_buffer_done(&buf->buf, VB2_BUF_STATE_DONE);
>
> -     wake_up(&buf->wait);
>       return nextbuf;
>  }
>
> @@ -576,7 +346,7 @@ static struct uvc_buffer *uvc_queue_head(struct
> uvc_video_queue *queue)
>
>       if (!list_empty(&queue->irqqueue))
>               buf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
> -                                    queue);
> +                                     queue);
>       else
>               queue->flags |= UVC_QUEUE_PAUSED;
>
> diff --git a/drivers/usb/gadget/uvc_queue.h
> b/drivers/usb/gadget/uvc_queue.h
> index 1812a8e..47ad0b8 100644
> --- a/drivers/usb/gadget/uvc_queue.h
> +++ b/drivers/usb/gadget/uvc_queue.h
> @@ -6,6 +6,7 @@
>  #include <linux/kernel.h>
>  #include <linux/poll.h>
>  #include <linux/videodev2.h>
> +#include <media/videobuf2-core.h>
>
>  /* Maximum frame size in bytes, for sanity checking. */
>  #define UVC_MAX_FRAME_SIZE   (16*1024*1024)
> @@ -25,14 +26,13 @@ enum uvc_buffer_state {
>  };
>
>  struct uvc_buffer {
> -     unsigned long vma_use_count;
> -     struct list_head stream;
> -
> -     /* Touched by interrupt handler. */
> -     struct v4l2_buffer buf;
> +     struct vb2_buffer buf;
>       struct list_head queue;
> -     wait_queue_head_t wait;
> +
>       enum uvc_buffer_state state;
> +     void *mem;
> +     unsigned int length;
> +     unsigned int bytesused;
>  };
>
>  #define UVC_QUEUE_STREAMING          (1 << 0)
> @@ -41,26 +41,21 @@ struct uvc_buffer {
>  #define UVC_QUEUE_PAUSED             (1 << 3)
>
>  struct uvc_video_queue {
> -     enum v4l2_buf_type type;
> +     struct vb2_queue queue;
> +     struct mutex mutex;     /* Protects queue */
>
> -     void *mem;
>       unsigned int flags;
>       __u32 sequence;
>
> -     unsigned int count;
> -     unsigned int buf_size;
>       unsigned int buf_used;
> -     struct uvc_buffer buffer[UVC_MAX_VIDEO_BUFFERS];
> -     struct mutex mutex;     /* protects buffers and mainqueue */
> -     spinlock_t irqlock;     /* protects irqqueue */
>
> -     struct list_head mainqueue;
> +     spinlock_t irqlock;     /* Protects irqqueue */
>       struct list_head irqqueue;
>  };
>
>  static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
>  {
> -     return queue->flags & UVC_QUEUE_STREAMING;
> +     return vb2_is_streaming(&queue->queue);
>  }
>
>  #endif /* __KERNEL__ */
> diff --git a/drivers/usb/gadget/uvc_v4l2.c
> b/drivers/usb/gadget/uvc_v4l2.c
> index f6e083b..9c2b45b 100644
> --- a/drivers/usb/gadget/uvc_v4l2.c
> +++ b/drivers/usb/gadget/uvc_v4l2.c
> @@ -144,20 +144,23 @@ uvc_v4l2_release(struct file *file)
>       struct uvc_device *uvc = video_get_drvdata(vdev);
>       struct uvc_file_handle *handle = to_uvc_file_handle(file-
> >private_data);
>       struct uvc_video *video = handle->device;
> +     int ret;
>
>       uvc_function_disconnect(uvc);
>
> -     uvc_video_enable(video, 0);
> -     mutex_lock(&video->queue.mutex);
> -     if (uvc_free_buffers(&video->queue) < 0)
> -             printk(KERN_ERR "uvc_v4l2_release: Unable to free "
> -                             "buffers.\n");
> -     mutex_unlock(&video->queue.mutex);
> +     ret = uvc_video_enable(video, 0);
> +     if (ret < 0) {
> +             printk(KERN_ERR "uvc_v4l2_release: uvc video disable
> failed\n");
> +             return ret;
> +     }
> +
> +     uvc_free_buffers(&video->queue);
>
>       file->private_data = NULL;
>       v4l2_fh_del(&handle->vfh);
>       v4l2_fh_exit(&handle->vfh);
>       kfree(handle);
> +
>       return 0;
>  }
>
> @@ -192,7 +195,7 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned int
> cmd, void *arg)
>       {
>               struct v4l2_format *fmt = arg;
>
> -             if (fmt->type != video->queue.type)
> +             if (fmt->type != video->queue.queue.type)
>                       return -EINVAL;
>
>               return uvc_v4l2_get_format(video, fmt);
> @@ -202,7 +205,7 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned int
> cmd, void *arg)
>       {
>               struct v4l2_format *fmt = arg;
>
> -             if (fmt->type != video->queue.type)
> +             if (fmt->type != video->queue.queue.type)
>                       return -EINVAL;
>
>               return uvc_v4l2_set_format(video, fmt);
> @@ -213,16 +216,13 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned int
> cmd, void *arg)
>       {
>               struct v4l2_requestbuffers *rb = arg;
>
> -             if (rb->type != video->queue.type ||
> -                 rb->memory != V4L2_MEMORY_MMAP)
> +             if (rb->type != video->queue.queue.type)
>                       return -EINVAL;
>
> -             ret = uvc_alloc_buffers(&video->queue, rb->count,
> -                                     video->imagesize);
> +             ret = uvc_alloc_buffers(&video->queue, rb);
>               if (ret < 0)
>                       return ret;
>
> -             rb->count = ret;
>               ret = 0;
>               break;
>       }
> @@ -231,9 +231,6 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned int
> cmd, void *arg)
>       {
>               struct v4l2_buffer *buf = arg;
>
> -             if (buf->type != video->queue.type)
> -                     return -EINVAL;
> -
>               return uvc_query_buffer(&video->queue, buf);
>       }
>
> @@ -251,7 +248,7 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned int
> cmd, void *arg)
>       {
>               int *type = arg;
>
> -             if (*type != video->queue.type)
> +             if (*type != video->queue.queue.type)
>                       return -EINVAL;
>
>               return uvc_video_enable(video, 1);
> @@ -261,14 +258,14 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned int
> cmd, void *arg)
>       {
>               int *type = arg;
>
> -             if (*type != video->queue.type)
> +             if (*type != video->queue.queue.type)
>                       return -EINVAL;
>
>               return uvc_video_enable(video, 0);
>       }
>
>       /* Events */
> -        case VIDIOC_DQEVENT:
> +     case VIDIOC_DQEVENT:
>       {
>               struct v4l2_event *event = arg;
>
> diff --git a/drivers/usb/gadget/uvc_video.c
> b/drivers/usb/gadget/uvc_video.c
> index b0e53a8..195bbb6 100644
> --- a/drivers/usb/gadget/uvc_video.c
> +++ b/drivers/usb/gadget/uvc_video.c
> @@ -32,7 +32,7 @@ uvc_video_encode_header(struct uvc_video *video,
> struct uvc_buffer *buf,
>       data[0] = 2;
>       data[1] = UVC_STREAM_EOH | video->fid;
>
> -     if (buf->buf.bytesused - video->queue.buf_used <= len - 2)
> +     if (buf->bytesused - video->queue.buf_used <= len - 2)
>               data[1] |= UVC_STREAM_EOF;
>
>       return 2;
> @@ -47,8 +47,8 @@ uvc_video_encode_data(struct uvc_video *video, struct
> uvc_buffer *buf,
>       void *mem;
>
>       /* Copy video data to the USB buffer. */
> -     mem = queue->mem + buf->buf.m.offset + queue->buf_used;
> -     nbytes = min((unsigned int)len, buf->buf.bytesused - queue-
> >buf_used);
> +     mem = buf->mem + queue->buf_used;
> +     nbytes = min((unsigned int)len, buf->bytesused - queue-
> >buf_used);
>
>       memcpy(data, mem, nbytes);
>       queue->buf_used += nbytes;
> @@ -82,7 +82,7 @@ uvc_video_encode_bulk(struct usb_request *req, struct
> uvc_video *video,
>       req->length = video->req_size - len;
>       req->zero = video->payload_size == video->max_payload_size;
>
> -     if (buf->buf.bytesused == video->queue.buf_used) {
> +     if (buf->bytesused == video->queue.buf_used) {
>               video->queue.buf_used = 0;
>               buf->state = UVC_BUF_STATE_DONE;
>               uvc_queue_next_buffer(&video->queue, buf);
> @@ -92,7 +92,7 @@ uvc_video_encode_bulk(struct usb_request *req, struct
> uvc_video *video,
>       }
>
>       if (video->payload_size == video->max_payload_size ||
> -         buf->buf.bytesused == video->queue.buf_used)
> +         buf->bytesused == video->queue.buf_used)
>               video->payload_size = 0;
>  }
>
> @@ -115,7 +115,7 @@ uvc_video_encode_isoc(struct usb_request *req,
> struct uvc_video *video,
>
>       req->length = video->req_size - len;
>
> -     if (buf->buf.bytesused == video->queue.buf_used) {
> +     if (buf->bytesused == video->queue.buf_used) {
>               video->queue.buf_used = 0;
>               buf->state = UVC_BUF_STATE_DONE;
>               uvc_queue_next_buffer(&video->queue, buf);
> @@ -161,6 +161,7 @@ static void
>  uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
>  {
>       struct uvc_video *video = req->context;
> +     struct uvc_video_queue *queue = &video->queue;
>       struct uvc_buffer *buf;
>       unsigned long flags;
>       int ret;
> @@ -169,13 +170,15 @@ uvc_video_complete(struct usb_ep *ep, struct
> usb_request *req)
>       case 0:
>               break;
>
> -     case -ESHUTDOWN:
> +     case -ESHUTDOWN:        /* disconnect from host. */
>               printk(KERN_INFO "VS request cancelled.\n");
> +             uvc_queue_cancel(queue, 1);
>               goto requeue;
>
>       default:
>               printk(KERN_INFO "VS request completed with status %d.\n",
>                       req->status);
> +             uvc_queue_cancel(queue, 0);
>               goto requeue;
>       }
>
> --
> 1.7.2.2

Regards,
Bhupesh
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