On Thu, 2 Dec 2010, Markus Niebel wrote: > Hello, > > we're working with a special cameraboard (CCD + Analog Frontend IC). Using the > soc_camera stack on the i.MX35 (mx3_camera) the following problem arises: > > VIDIOC_STREAMON calls soc_camera_streamon which calls videobuf_streamon - when > iterating the buffers in the queue the function mx3_videobuf_queue is called > for every buffer. This sends the buffers to the omage DMA (IDMAC) using the > tx_submit method. The function ipu_init_channel_buffer (DMA driver ipu_core) > gets only one buffer from the scatterlist, this leads to a single buffer > capture. > > In the code of mx3_videobuf_prepare there is a comment, that the first > buffer's scatterlist needs to contain two buffers but this is not implemented. > > I try to understand the interworking of the parts (soc_camera, videobuf, > ipu_core and mx3_camera) and would help to fix it. Here's the comment, you are referring to: /* * We will have to configure the IDMAC channel. It has two slots * for DMA buffers, we shall enter the first two buffers there, * and then submit new buffers in DMA-ready interrupts */ It says nothing about the scatter-list. Each buffer is submitted in an own sg-list with one element. They get queued in the ipu_idmac dmaengine driver. So, you just have to queue several buffers in your application before going to the dequeue stage. Look at contrib/test/capture-example.c from http://git.linuxtv.org/v4l-utils.git for an example. Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- 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
