On 04/12/2017 04:29 PM, Patrick Doyle wrote: > Thank you again Hans. > > On Wed, Apr 12, 2017 at 9:58 AM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote: >> On 04/12/2017 03:13 PM, Patrick Doyle wrote: >>> The SAMA5 has a downsampler built into its LCD engine. Suppose I >>> wanted to treat that downsampler as an independent device and pass >>> image buffers through that downsampler (the LCD display output is >>> disabled in hardware when the device is configured in this mode).... >>> do you have any recommendations as to how I might structure a device >>> driver to do that. At it's core, it would DMA a buffer from memory, >>> through the downsampler, and back into memory. Is that something I >>> might also wire in as a pseudo-subdev of the ISC? Or is there a >>> better abstraction for arbitrary image processing pipeline elements? >> >> I think this is out of scope of V4L2. Check with Atmel/Microchip. > > The V4L2 tie-in is in answering the question: Is there a standard V4L2 > way to perform arbitrary video processing functions (such as > downsampling) with an arbitrary device. If the answer is "no", that's > fine. If the answer is, "yes, here is how Xilinx does it for their IP > modules", then I'll go look at some Xilinx stuff (which I'm going to > do anyway). VIDIOC_S_FMT: the pixelformat you specify in the v4l2_pix_format struct determines Bayer vs YUV 4:2:2 vs YUV 4:2:0 vs RGB. So that triggers whatever conversion is needed to arrive at the desired memory format. https://www.linuxtv.org/downloads/v4l-dvb-apis-new/uapi/v4l/vidioc-g-fmt.html Regards, Hans
