发布: [02-3]_videobuffer2缓冲区结构体

IMX6ULL/doc_pic/13_V4L2/02_V4L2驱动程序框架.md

@@ -3,6 +3,7 @@
 参考资料：
 
 * 深入理解linux内核v4l2框架之videobuf2：https://blog.csdn.net/yyjsword/article/details/9243717
+* V4L2框架-videobuf2：https://blog.csdn.net/u013904227/article/details/81054611
 
 ## 1. 整体框架
 
@@ -107,5 +108,41 @@ APP操作buffer的示意图如下：
 
 
 
+#### 1.3.1 videobuffer2缓冲区结构体
+
+![image-20230810163245420](pic/29_videobuffer2_struct.png)
+
+分配流程：
+
+* 驱动程序初始化时，就构造了vb2_queue，这是"buffer的队列"，一开始里面没有"buffer"
+* APP调用ioctl VIDIOC_REQBUFS向驱动申请N个buffer
+* 驱动程序分配n(n<=N)个vb2_buffer结构体，然后
+  * 对于普通摄像头，还分配一个vb2_plane结构体、vb2_vmalloc_buf结构体，最后分配存数据的buffer
+  * 对于多平面摄像头，给每个vb2_buffer分配多个"vb2_plane结构体、vb2_vmalloc_buf结构体、存数据的buffer"
+
+
+
+入队列流程：
+
+* APP调用ioctl VIDIOC_QBUF
+* 驱动程序根据其index找到vb2_buffer
+* 把这个vb2_buffer放入链表vb2_queue.queued_list
+
+硬件驱动接收到数据后，比如URB传输完成后：
+
+* 从链表vb2_queue.queued_list取出vb2_buffer
+* 把硬件数据存入vb2_buffer
+* 把vb2_buffer放入链表vb2_queue.done_list
+
+出队列流程：
+
+* APP调用ioctl VIDIOC_DQBUF
+* 驱动程序从链表vb2_queue.done_list取出并移除第1个vb2_buffer
+* 驱动程序也把这个vb2_buffer从链表vb2_queue.queued_list移除
+
+
+
+
+
 ## 2. 从0编写一个虚拟的摄像头驱动
 

IMX6ULL/doc_pic/13_V4L2/笔记.md

@@ -20,6 +20,8 @@ GIT简明教程：http://download.100ask.org/tools/Software/git/how_to_use_git.h
 
 ## 2. 收到的建议
 
+![image-20230804075519837](pic/28_suggestion.png)
+
 subdev, media control, media framework, vb2 buffer的分配，怎么轮转，怎么跟硬件打交道，然后图像给应用层用
 
 有的摄像头有控制接口iic,spi，还有没有控制接口的，我们怎么处理？
@@ -225,3 +227,236 @@ V4L2 capture overlay
 
 
 
+## 4. videobuffer2
+
+参考资料：
+
+* https://www.linuxtv.org/downloads/v4l-dvb-apis-old/vidioc-create-bufs.html
+* https://www.linuxtv.org/downloads/v4l-dvb-apis-old/buffer.html#v4l2-memory
+* https://www.linuxtv.org/downloads/v4l-dvb-apis-old/mmap.html
+* V4l2应用框架-Videobuf2数据结构 https://blog.csdn.net/weixin_42581177/article/details/126582465
+
+
+
+```c
+static const struct vb2_ops airspy_vb2_ops = {
+	.queue_setup            = airspy_queue_setup,
+	.buf_queue              = airspy_buf_queue,
+	.start_streaming        = airspy_start_streaming,
+	.stop_streaming         = airspy_stop_streaming,
+	.wait_prepare           = vb2_ops_wait_prepare,
+	.wait_finish            = vb2_ops_wait_finish,
+};
+
+const struct vb2_mem_ops vb2_vmalloc_memops = {
+	.alloc		= vb2_vmalloc_alloc,
+	.put		= vb2_vmalloc_put,
+	.get_userptr	= vb2_vmalloc_get_userptr,
+	.put_userptr	= vb2_vmalloc_put_userptr,
+#ifdef CONFIG_HAS_DMA
+	.get_dmabuf	= vb2_vmalloc_get_dmabuf,
+#endif
+	.map_dmabuf	= vb2_vmalloc_map_dmabuf,
+	.unmap_dmabuf	= vb2_vmalloc_unmap_dmabuf,
+	.attach_dmabuf	= vb2_vmalloc_attach_dmabuf,
+	.detach_dmabuf	= vb2_vmalloc_detach_dmabuf,
+	.vaddr		= vb2_vmalloc_vaddr,
+	.mmap		= vb2_vmalloc_mmap,
+	.num_users	= vb2_vmalloc_num_users,
+};
+
+
+s->vb_queue.ops = &airspy_vb2_ops;          // call_qop,call_vb_qop
+s->vb_queue.mem_ops = &vb2_vmalloc_memops;  // call_ptr_memop
+
+int vb2_queue_init(struct vb2_queue *q)
+		q->buf_ops = &v4l2_buf_ops;
+```
+
+
+
+### 4.1 APP request buf
+
+```c
+ioctl(fd, VIDIOC_REQBUFS, &rb);
+--------------------------------
+    v4l_reqbufs(const struct v4l2_ioctl_ops *ops,
+		ops->vidioc_reqbufs(file, fh, p);
+			vb2_ioctl_reqbufs
+                res = vb2_core_reqbufs(vdev->queue, p->memory, &p->count);
+                		num_buffers = min_t(unsigned int, *count, VB2_MAX_FRAME);
+						num_buffers = max_t(unsigned int, num_buffers, q->min_buffers_needed);
+
+                		// 给你机会修改num_buffers,num_planes
+                		ret = call_qop(q, queue_setup, q, &num_buffers, &num_planes,		     								  plane_sizes, q->alloc_devs); // airspy_queue_setup
+
+                        /* Finally, allocate buffers and video memory */
+                        allocated_buffers =
+                            __vb2_queue_alloc(q, memory, num_buffers, num_planes, plane_sizes);
+             					ret = __vb2_buf_mem_alloc(vb);
+                							call_ptr_memop(vb, alloc,
+                                                 vb2_queue->mem_ops->alloc
+                                                        vb2_vmalloc_alloc
+                                                           buf->vaddr = vmalloc_user(buf->size);
+                				ret = call_vb_qop(vb, buf_init, vb);
+                				
+```
+
+
+
+### 4.2 queue buffer
+
+queue buffer关键点：
+
+* VB2的链表：list_add_tail(&vb->queued_entry, &q->queued_list);
+* 驱动自己维护的链表：list_add_tail(&buf->list, &s->queued_bufs);
+
+驱动的URB传输完成后：
+
+* 从链表queued_bufs取出buffer
+* 把URB得到的数据填入buffer
+* 调用vb2_buffer_done：list_add_tail(&vb->done_entry, &q->done_list);
+
+dequeue buffer关键点：
+
+* 从链表done_entry取出并移除第1个vb
+* 把它也从queued_list中移除
+
+```c
+ioctl(fd, VIDIOC_QBUF, &buf)
+-------------------------------
+    v4l_qbuf
+    	ops->vidioc_qbuf(file, fh, p);
+			vb2_ioctl_qbuf
+                vb2_qbuf(vdev->queue, p);
+					vb2_queue_or_prepare_buf(q, b, "qbuf");
+					vb2_core_qbuf(q, b->index, b);
+						list_add_tail(&vb->queued_entry, &q->queued_list);
+						vb->state = VB2_BUF_STATE_QUEUED;
+
+                            /*
+                             * If already streaming, give the buffer to driver for processing.
+                             * If not, the buffer will be given to driver on next streamon.
+                             */
+                            if (q->start_streaming_called)
+                                __enqueue_in_driver(vb);
+                                        /* sync buffers */
+                                        for (plane = 0; plane < vb->num_planes; ++plane)
+                                            call_void_memop(vb, prepare, vb->planes[plane].mem_priv);
+
+                                        call_void_vb_qop(vb, buf_queue, vb);
+											airspy_buf_queue
+                                                list_add_tail(&buf->list, &s->queued_bufs);
+
+                        if (pb)
+                            call_void_bufop(q, fill_user_buffer, vb, pb);
+					
+```
+
+
+
+### 4.3 dequeue buf
+
+```shell
+ioctl(fd, VIDIOC_DQBUF, &buf)
+----------------------------------
+	v4l_dqbuf
+		ops->vidioc_dqbuf(file, fh, p);
+			vb2_ioctl_dqbuf
+				vb2_dqbuf(vdev->queue, p, file->f_flags & O_NONBLOCK);
+					ret = vb2_core_dqbuf(q, NULL, b, nonblocking);
+							ret = __vb2_get_done_vb(q, &vb, pb, nonblocking);
+									*vb = list_first_entry(&q->done_list, struct vb2_buffer, done_entry);
+									list_del(&(*vb)->done_entry);
+							call_void_vb_qop(vb, buf_finish, vb);
+							call_void_bufop(q, fill_user_buffer, vb, pb);
+							__vb2_dqbuf(vb);
+
+```
+
+
+
+### 4.3 stream on
+
+```c
+ioctl(fd, VIDIOC_STREAMON, &type)
+------------------------------------
+    v4l_streamon
+    	ops->vidioc_streamon(file, fh, *(unsigned int *)arg)
+    		vb2_ioctl_streamon
+    			vb2_streamon(vdev->queue, i);
+					vb2_core_streamon(q, type);
+						ret = vb2_start_streaming(q);
+                                    /*
+                                     * If any buffers were queued before streamon,
+                                     * we can now pass them to driver for processing.
+                                     */
+                                    list_for_each_entry(vb, &q->queued_list, queued_entry)
+                                        __enqueue_in_driver(vb);
+                                                /* sync buffers */
+                                                for (plane = 0; plane < vb->num_planes; ++plane)
+                                                    call_void_memop(vb, prepare, vb->planes[plane].mem_priv);
+
+                                                call_void_vb_qop(vb, buf_queue, vb);
+													airspy_buf_queue			
+
+                                    /* Tell the driver to start streaming */
+                                    q->start_streaming_called = 1;
+                                    ret = call_qop(q, start_streaming, q, atomic_read(&q->owned_by_drv_count));
+												airspy_start_streaming // 分配提交URB
+                                                    
+
+```
+
+
+
+### 4.3 stream off
+
+```c
+ioctl(fd, VIDIOC_STREAMOFF, &type)
+-----------------------------------
+    v4l_streamoff
+    	ops->vidioc_streamoff(file, fh, *(unsigned int *)arg);
+			vb2_ioctl_streamoff
+                vb2_streamoff(vdev->queue, i);	
+                	vb2_core_streamoff(q, type);
+						__vb2_queue_cancel(q);
+							call_void_qop(q, stop_streaming, q);
+								airspy_stop_streaming // kill URB
+                                    
+							call_void_vb_qop(vb, buf_finish, vb);
+```
+
+
+
+### 4.4 阻塞与唤醒
+
+#### 4.4.1 阻塞
+
+```shell
+memset(fds, 0, sizeof(fds));
+fds[0].fd = fd;
+fds[0].events = POLLIN;
+if (1 == poll(fds, 1, -1))
+--------------------------------------
+v4l2_poll
+	res = vdev->fops->poll(filp, poll);
+			vb2_fop_poll
+				res = vb2_poll(vdev->queue, file, wait);
+							vb2_core_poll(q, file, wait);
+								poll_wait(file, &q->done_wq, wait);
+```
+
+#### 4.4.2 唤醒
+
+```shell
+airspy_urb_complete
+	vb2_buffer_done(&fbuf->vb.vb2_buf, VB2_BUF_STATE_DONE);
+```
+
+
+
+### 4.6 读写buf
+
+
+

README.md

@@ -796,6 +796,12 @@ git clone https://e.coding.net/weidongshan/linux/doc_and_source_for_drivers.git
   [02-2]_ioctl调用流程分析
   ```
 
+* 2023.08.10 发布"摄像头驱动"
+
+  ```shell
+  [02-3]_videobuffer2缓冲区结构体
+  ```
+
   
 
 

STM32MP157/doc_pic/13_V4L2/02_V4L2驱动程序框架.md

@@ -3,6 +3,7 @@
 参考资料：
 
 * 深入理解linux内核v4l2框架之videobuf2：https://blog.csdn.net/yyjsword/article/details/9243717
+* V4L2框架-videobuf2：https://blog.csdn.net/u013904227/article/details/81054611
 
 ## 1. 整体框架
 
@@ -107,5 +108,41 @@ APP操作buffer的示意图如下：
 
 
 
+#### 1.3.1 videobuffer2缓冲区结构体
+
+![image-20230810163245420](pic/29_videobuffer2_struct.png)
+
+分配流程：
+
+* 驱动程序初始化时，就构造了vb2_queue，这是"buffer的队列"，一开始里面没有"buffer"
+* APP调用ioctl VIDIOC_REQBUFS向驱动申请N个buffer
+* 驱动程序分配n(n<=N)个vb2_buffer结构体，然后
+  * 对于普通摄像头，还分配一个vb2_plane结构体、vb2_vmalloc_buf结构体，最后分配存数据的buffer
+  * 对于多平面摄像头，给每个vb2_buffer分配多个"vb2_plane结构体、vb2_vmalloc_buf结构体、存数据的buffer"
+
+
+
+入队列流程：
+
+* APP调用ioctl VIDIOC_QBUF
+* 驱动程序根据其index找到vb2_buffer
+* 把这个vb2_buffer放入链表vb2_queue.queued_list
+
+硬件驱动接收到数据后，比如URB传输完成后：
+
+* 从链表vb2_queue.queued_list取出vb2_buffer
+* 把硬件数据存入vb2_buffer
+* 把vb2_buffer放入链表vb2_queue.done_list
+
+出队列流程：
+
+* APP调用ioctl VIDIOC_DQBUF
+* 驱动程序从链表vb2_queue.done_list取出并移除第1个vb2_buffer
+* 驱动程序也把这个vb2_buffer从链表vb2_queue.queued_list移除
+
+
+
+
+
 ## 2. 从0编写一个虚拟的摄像头驱动
 

STM32MP157/doc_pic/13_V4L2/笔记.md

@@ -20,6 +20,8 @@ GIT简明教程：http://download.100ask.org/tools/Software/git/how_to_use_git.h
 
 ## 2. 收到的建议
 
+![image-20230804075519837](pic/28_suggestion.png)
+
 subdev, media control, media framework, vb2 buffer的分配，怎么轮转，怎么跟硬件打交道，然后图像给应用层用
 
 有的摄像头有控制接口iic,spi，还有没有控制接口的，我们怎么处理？
@@ -225,3 +227,236 @@ V4L2 capture overlay
 
 
 
+## 4. videobuffer2
+
+参考资料：
+
+* https://www.linuxtv.org/downloads/v4l-dvb-apis-old/vidioc-create-bufs.html
+* https://www.linuxtv.org/downloads/v4l-dvb-apis-old/buffer.html#v4l2-memory
+* https://www.linuxtv.org/downloads/v4l-dvb-apis-old/mmap.html
+* V4l2应用框架-Videobuf2数据结构 https://blog.csdn.net/weixin_42581177/article/details/126582465
+
+
+
+```c
+static const struct vb2_ops airspy_vb2_ops = {
+	.queue_setup            = airspy_queue_setup,
+	.buf_queue              = airspy_buf_queue,
+	.start_streaming        = airspy_start_streaming,
+	.stop_streaming         = airspy_stop_streaming,
+	.wait_prepare           = vb2_ops_wait_prepare,
+	.wait_finish            = vb2_ops_wait_finish,
+};
+
+const struct vb2_mem_ops vb2_vmalloc_memops = {
+	.alloc		= vb2_vmalloc_alloc,
+	.put		= vb2_vmalloc_put,
+	.get_userptr	= vb2_vmalloc_get_userptr,
+	.put_userptr	= vb2_vmalloc_put_userptr,
+#ifdef CONFIG_HAS_DMA
+	.get_dmabuf	= vb2_vmalloc_get_dmabuf,
+#endif
+	.map_dmabuf	= vb2_vmalloc_map_dmabuf,
+	.unmap_dmabuf	= vb2_vmalloc_unmap_dmabuf,
+	.attach_dmabuf	= vb2_vmalloc_attach_dmabuf,
+	.detach_dmabuf	= vb2_vmalloc_detach_dmabuf,
+	.vaddr		= vb2_vmalloc_vaddr,
+	.mmap		= vb2_vmalloc_mmap,
+	.num_users	= vb2_vmalloc_num_users,
+};
+
+
+s->vb_queue.ops = &airspy_vb2_ops;          // call_qop,call_vb_qop
+s->vb_queue.mem_ops = &vb2_vmalloc_memops;  // call_ptr_memop
+
+int vb2_queue_init(struct vb2_queue *q)
+		q->buf_ops = &v4l2_buf_ops;
+```
+
+
+
+### 4.1 APP request buf
+
+```c
+ioctl(fd, VIDIOC_REQBUFS, &rb);
+--------------------------------
+    v4l_reqbufs(const struct v4l2_ioctl_ops *ops,
+		ops->vidioc_reqbufs(file, fh, p);
+			vb2_ioctl_reqbufs
+                res = vb2_core_reqbufs(vdev->queue, p->memory, &p->count);
+                		num_buffers = min_t(unsigned int, *count, VB2_MAX_FRAME);
+						num_buffers = max_t(unsigned int, num_buffers, q->min_buffers_needed);
+
+                		// 给你机会修改num_buffers,num_planes
+                		ret = call_qop(q, queue_setup, q, &num_buffers, &num_planes,		     								  plane_sizes, q->alloc_devs); // airspy_queue_setup
+
+                        /* Finally, allocate buffers and video memory */
+                        allocated_buffers =
+                            __vb2_queue_alloc(q, memory, num_buffers, num_planes, plane_sizes);
+             					ret = __vb2_buf_mem_alloc(vb);
+                							call_ptr_memop(vb, alloc,
+                                                 vb2_queue->mem_ops->alloc
+                                                        vb2_vmalloc_alloc
+                                                           buf->vaddr = vmalloc_user(buf->size);
+                				ret = call_vb_qop(vb, buf_init, vb);
+                				
+```
+
+
+
+### 4.2 queue buffer
+
+queue buffer关键点：
+
+* VB2的链表：list_add_tail(&vb->queued_entry, &q->queued_list);
+* 驱动自己维护的链表：list_add_tail(&buf->list, &s->queued_bufs);
+
+驱动的URB传输完成后：
+
+* 从链表queued_bufs取出buffer
+* 把URB得到的数据填入buffer
+* 调用vb2_buffer_done：list_add_tail(&vb->done_entry, &q->done_list);
+
+dequeue buffer关键点：
+
+* 从链表done_entry取出并移除第1个vb
+* 把它也从queued_list中移除
+
+```c
+ioctl(fd, VIDIOC_QBUF, &buf)
+-------------------------------
+    v4l_qbuf
+    	ops->vidioc_qbuf(file, fh, p);
+			vb2_ioctl_qbuf
+                vb2_qbuf(vdev->queue, p);
+					vb2_queue_or_prepare_buf(q, b, "qbuf");
+					vb2_core_qbuf(q, b->index, b);
+						list_add_tail(&vb->queued_entry, &q->queued_list);
+						vb->state = VB2_BUF_STATE_QUEUED;
+
+                            /*
+                             * If already streaming, give the buffer to driver for processing.
+                             * If not, the buffer will be given to driver on next streamon.
+                             */
+                            if (q->start_streaming_called)
+                                __enqueue_in_driver(vb);
+                                        /* sync buffers */
+                                        for (plane = 0; plane < vb->num_planes; ++plane)
+                                            call_void_memop(vb, prepare, vb->planes[plane].mem_priv);
+
+                                        call_void_vb_qop(vb, buf_queue, vb);
+											airspy_buf_queue
+                                                list_add_tail(&buf->list, &s->queued_bufs);
+
+                        if (pb)
+                            call_void_bufop(q, fill_user_buffer, vb, pb);
+					
+```
+
+
+
+### 4.3 dequeue buf
+
+```shell
+ioctl(fd, VIDIOC_DQBUF, &buf)
+----------------------------------
+	v4l_dqbuf
+		ops->vidioc_dqbuf(file, fh, p);
+			vb2_ioctl_dqbuf
+				vb2_dqbuf(vdev->queue, p, file->f_flags & O_NONBLOCK);
+					ret = vb2_core_dqbuf(q, NULL, b, nonblocking);
+							ret = __vb2_get_done_vb(q, &vb, pb, nonblocking);
+									*vb = list_first_entry(&q->done_list, struct vb2_buffer, done_entry);
+									list_del(&(*vb)->done_entry);
+							call_void_vb_qop(vb, buf_finish, vb);
+							call_void_bufop(q, fill_user_buffer, vb, pb);
+							__vb2_dqbuf(vb);
+
+```
+
+
+
+### 4.3 stream on
+
+```c
+ioctl(fd, VIDIOC_STREAMON, &type)
+------------------------------------
+    v4l_streamon
+    	ops->vidioc_streamon(file, fh, *(unsigned int *)arg)
+    		vb2_ioctl_streamon
+    			vb2_streamon(vdev->queue, i);
+					vb2_core_streamon(q, type);
+						ret = vb2_start_streaming(q);
+                                    /*
+                                     * If any buffers were queued before streamon,
+                                     * we can now pass them to driver for processing.
+                                     */
+                                    list_for_each_entry(vb, &q->queued_list, queued_entry)
+                                        __enqueue_in_driver(vb);
+                                                /* sync buffers */
+                                                for (plane = 0; plane < vb->num_planes; ++plane)
+                                                    call_void_memop(vb, prepare, vb->planes[plane].mem_priv);
+
+                                                call_void_vb_qop(vb, buf_queue, vb);
+													airspy_buf_queue			
+
+                                    /* Tell the driver to start streaming */
+                                    q->start_streaming_called = 1;
+                                    ret = call_qop(q, start_streaming, q, atomic_read(&q->owned_by_drv_count));
+												airspy_start_streaming // 分配提交URB
+                                                    
+
+```
+
+
+
+### 4.3 stream off
+
+```c
+ioctl(fd, VIDIOC_STREAMOFF, &type)
+-----------------------------------
+    v4l_streamoff
+    	ops->vidioc_streamoff(file, fh, *(unsigned int *)arg);
+			vb2_ioctl_streamoff
+                vb2_streamoff(vdev->queue, i);	
+                	vb2_core_streamoff(q, type);
+						__vb2_queue_cancel(q);
+							call_void_qop(q, stop_streaming, q);
+								airspy_stop_streaming // kill URB
+                                    
+							call_void_vb_qop(vb, buf_finish, vb);
+```
+
+
+
+### 4.4 阻塞与唤醒
+
+#### 4.4.1 阻塞
+
+```shell
+memset(fds, 0, sizeof(fds));
+fds[0].fd = fd;
+fds[0].events = POLLIN;
+if (1 == poll(fds, 1, -1))
+--------------------------------------
+v4l2_poll
+	res = vdev->fops->poll(filp, poll);
+			vb2_fop_poll
+				res = vb2_poll(vdev->queue, file, wait);
+							vb2_core_poll(q, file, wait);
+								poll_wait(file, &q->done_wq, wait);
+```
+
+#### 4.4.2 唤醒
+
+```shell
+airspy_urb_complete
+	vb2_buffer_done(&fbuf->vb.vb2_buf, VB2_BUF_STATE_DONE);
+```
+
+
+
+### 4.6 读写buf
+
+
+