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[Linux-uvc-devel] Comments about the driver
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From: Luc S. <lu...@sa...> - 2006-01-04 12:30:51
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Some comments about the current driver.
I'll try tonight the driver, and thanks for writing the driver.
Luc
>
> /*
> * usbvideo.c -- USB Video Class driver
> *
> * Copyright (C) 2005
Now you can update the year :-)
> * Laurent Pinchart (lau...@sk...)
> *
> * 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.
> *
> */
> * Don't try to open the driver multiple times ! This will crash and make your
> * computer explode (well, maybe not, but still, don't do it). I plan to fix
> * that in the very near future. You have been warned.
You can just put a counter in the uvc_v4l2_open() and when the counter != 0
don't try to continue.
> struct uvc_terminal {
> struct list_head list;
>
> __u8 id;
> __u16 type;
> char name[64];
>
> union {
> struct {
> __u16 wObjectiveFocalLengthMin;
> __u16 wObjectiveFocalLengthMax;
> __u16 wOcularFocalLength;
> __u8 bControlSize;
> __u8 *bmControls;
> } camera;
>
> struct {
> __u8 bSourceID;
> } output;
> };
> };
union without name can't be build with gcc2.95 is it ok ?
>
> struct uvc_unit {
> struct list_head list;
>
> int id;
> int type;
> char name[64];
> };
>
> struct uvc_control_desc uvc_ctrls[] = {
> {
put a static here too.
> /*
> * Allocate the video buffers.
> *
> * Pages are reserved to make sure they will not be swaped, as they will be
> * filled in 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)
> {
> unsigned int bufsize = PAGE_ALIGN(buflength);
> unsigned int i;
> void *mem = NULL;
> int ret;
>
> if (nbuffers > UVC_MAX_VIDEO_BUFFERS)
> nbuffers = UVC_MAX_VIDEO_BUFFERS;
>
> down(&queue->lock);
>
> if ((ret = uvc_free_buffers(queue)) < 0)
> goto done;
>
> /* Decrement the number of buffers until allocation succeeds. */
> for (; nbuffers > 0; --nbuffers) {
> mem = vmalloc_32(nbuffers * bufsize);
> if (mem != NULL)
> break;
> }
>
> if (mem == NULL)
> return -ENOMEM;
^^^^ return without a up()
ret = -ENOMEM;
goto done;
>
> for (i = 0; i < nbuffers; ++i) {
> memset(&queue->buffer[i], 0, sizeof queue->buffer[i]);
> queue->buffer[i].size = bufsize;
> queue->buffer[i].buf.index = i;
> queue->buffer[i].buf.m.offset = i * bufsize;
Is any buffersize aligned on a page boudary ?
> queue->buffer[i].buf.length = buflength;
> queue->buffer[i].buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> 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);
> }
>
> queue->mem = mem;
> queue->count = nbuffers;
> ret = nbuffers;
>
> done:
> up(&queue->lock);
> return ret;
> }
>
> /*
> * Dequeue a video buffer. If nonblocking is false, block until a buffer is
> * available.
> */
> static int uvc_dequeue_buffer(struct uvc_video_queue *queue,
> struct v4l2_buffer *v4l2_buf, int nonblocking)
> {
> struct uvc_buffer *buf;
> int ret = 0;
>
> if (v4l2_buf->type != V4L2_BUF_TYPE_VIDEO_CAPTURE ||
> v4l2_buf->memory != V4L2_MEMORY_MMAP)
> return -EINVAL;
>
> down(&queue->lock);
> if (list_empty(&queue->mainqueue)) {
> ret = -EINVAL;
> goto done;
> }
>
> buf = list_entry(queue->mainqueue.next, struct uvc_buffer, stream);
> if ((ret = uvc_queue_waiton(buf, nonblocking)) < 0)
> goto done;
>
> switch (buf->state) {
> case UVC_BUF_STATE_ERROR:
> ret = -EIO;
^^^^ ? need a goto done or is it wanted ?
> 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:
> ret = -EINVAL;
> goto done;
> }
>
> list_del(&buf->stream);
> memcpy(v4l2_buf, &buf->buf, sizeof *v4l2_buf);
>
> done:
> up(&queue->lock);
> return ret;
> }
>
> /*
> * Queue a video buffer. Attempting to queue a buffer that has already been
> * queued will return -EINVAL.
> */
> static int uvc_queue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *v4l2_buf)
> {
> struct uvc_buffer *buf;
> unsigned long flags;
> int ret = 0;
>
> if (v4l2_buf->type != V4L2_BUF_TYPE_VIDEO_CAPTURE ||
> v4l2_buf->memory != V4L2_MEMORY_MMAP)
> return -EINVAL;
>
> down(&queue->lock);
> if (v4l2_buf->index >= queue->count) {
> ret = -EINVAL;
> goto done;
> }
>
> buf = &queue->buffer[v4l2_buf->index];
> if (buf->state != UVC_BUF_STATE_IDLE) {
> ret = -EINVAL;
> goto done;
> }
>
> buf->state = UVC_BUF_STATE_QUEUED;
> buf->buf.bytesused = 0;
> list_add_tail(&buf->stream, &queue->mainqueue);
> spin_lock_irqsave(&queue->irqlock, flags);
> list_add_tail(&buf->queue, &queue->irqqueue);
> spin_unlock_irqrestore(&queue->irqlock, flags);
>
> done:
> up(&queue->lock);
> return ret;
> }
>
}
>
> static int uvc_set_video_ctrl(struct uvc_video_device *video,
> struct uvc_streaming_control *ctrl, int probe)
> {
> __u8 data[34];
is it not posible to create a structure and access it ?
i think it will more readable than data[2] ?
> __u8 size;
>
> size = video->dev->uvc_version > 0x0100 ? 34 : 26;
> memset(data, 0, sizeof data);
>
> *(__le16*)&data[0] = cpu_to_le32(ctrl->bmHint);
> data[2] = ctrl->bFormatIndex;
> data[3] = ctrl->bFrameIndex;
> *(__le32*)&data[4] = cpu_to_le32(ctrl->dwFrameInterval);
> *(__le16*)&data[8] = cpu_to_le16(ctrl->wKeyFrameRate);
> *(__le16*)&data[10] = cpu_to_le16(ctrl->wPFrameRate);
> *(__le16*)&data[12] = cpu_to_le16(ctrl->wCompQuality);
> *(__le16*)&data[14] = cpu_to_le16(ctrl->wCompWindowSize);
> *(__le16*)&data[16] = cpu_to_le16(ctrl->wDelay);
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