Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3) ********
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4) Examples
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) ********
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) (A video capture device is assumed; change
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) ``V4L2_BUF_TYPE_VIDEO_CAPTURE`` for other devices; change target to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) ``V4L2_SEL_TGT_COMPOSE_*`` family to configure composing area)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) Example: Resetting the cropping parameters
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) ==========================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) .. code-block:: c
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) 	struct v4l2_selection sel = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) 	    .type = V4L2_BUF_TYPE_VIDEO_CAPTURE,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) 	    .target = V4L2_SEL_TGT_CROP_DEFAULT,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) 	};
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) 	ret = ioctl(fd, VIDIOC_G_SELECTION, &sel);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) 	if (ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) 	    exit(-1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) 	sel.target = V4L2_SEL_TGT_CROP;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 	ret = ioctl(fd, VIDIOC_S_SELECTION, &sel);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) 	if (ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) 	    exit(-1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) Setting a composing area on output of size of *at most* half of limit
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) placed at a center of a display.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) Example: Simple downscaling
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) ===========================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) .. code-block:: c
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 	struct v4l2_selection sel = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) 	    .type = V4L2_BUF_TYPE_VIDEO_OUTPUT,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 	    .target = V4L2_SEL_TGT_COMPOSE_BOUNDS,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) 	};
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) 	struct v4l2_rect r;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) 	ret = ioctl(fd, VIDIOC_G_SELECTION, &sel);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) 	if (ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) 	    exit(-1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) 	/* setting smaller compose rectangle */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 	r.width = sel.r.width / 2;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) 	r.height = sel.r.height / 2;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) 	r.left = sel.r.width / 4;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) 	r.top = sel.r.height / 4;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) 	sel.r = r;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) 	sel.target = V4L2_SEL_TGT_COMPOSE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) 	sel.flags = V4L2_SEL_FLAG_LE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) 	ret = ioctl(fd, VIDIOC_S_SELECTION, &sel);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) 	if (ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) 	    exit(-1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) A video output device is assumed; change ``V4L2_BUF_TYPE_VIDEO_OUTPUT``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) for other devices
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) Example: Querying for scaling factors
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) =====================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) .. code-block:: c
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) 	struct v4l2_selection compose = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) 	    .type = V4L2_BUF_TYPE_VIDEO_OUTPUT,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) 	    .target = V4L2_SEL_TGT_COMPOSE,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) 	};
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) 	struct v4l2_selection crop = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) 	    .type = V4L2_BUF_TYPE_VIDEO_OUTPUT,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) 	    .target = V4L2_SEL_TGT_CROP,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) 	};
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) 	double hscale, vscale;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) 	ret = ioctl(fd, VIDIOC_G_SELECTION, &compose);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) 	if (ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) 	    exit(-1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) 	ret = ioctl(fd, VIDIOC_G_SELECTION, &crop);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) 	if (ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) 	    exit(-1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) 	/* computing scaling factors */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) 	hscale = (double)compose.r.width / crop.r.width;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) 	vscale = (double)compose.r.height / crop.r.height;