Hi Benjamin, On Mo, 2023-12-04 at 14:23 +0100, Benjamin Gaignard wrote: > 'min_buffers_needed' is suppose to be used to indicate the number > of buffers needed by DMA engine to start streaming. > imx-media-capture driver doesn't use DMA engine and just want to specify > the minimum number of buffers to allocate when calling VIDIOC_REQBUFS. This is used by imx-media-csi and imx-ic-prpencvf. Both expect two buffers to setup the IDMAC DMA engine double buffer (see csi_idmac_setup_vb2_buf()/prp_setup_vb2_buf()). These functions can cope with less than two buffers queued, by using a special "underrun" buffer as a workaround, but the hardware does require two buffer addresses, so I'm not sure whether this really should be called a misuse of min_buffers_needed. regards Philipp
