On 14/02/18 13:27, Florian Echtler wrote: > Hello Hans, > > On 14.02.2018 13:13, Hans Verkuil wrote: >> >> On 14/02/18 13:09, Florian Echtler wrote: >>> >>> The internal device memory contains a table with two bytes for each sensor pixel >>> (i.e. 960x540x2 = 1036800 bytes) that basically provide individual black and >>> white levels per-pixel that are used in preprocessing. The table can either be >>> set externally, or the sensor can be covered with a black/white surface and a >>> custom command triggers an internal calibration. >>> >>> AFAICT the usual V4L2 controls are unsuitable for this sort of data; do you have >>> any suggestions on how to approach this? Maybe something like a custom IOCTL? >> >> So the table has a fixed size? >> You can use array controls for that, a V4L2_CTRL_TYPE_U16 in a two-dimensional array >> would do it. > > Good to know, thanks. > >> See https://hverkuil.home.xs4all.nl/spec/uapi/v4l/vidioc-queryctrl.html for more >> information on how this works. > > This means I have to implement QUERY_EXT_CTRL, G_EXT_CTRLS and S_EXT_CTRLS, > correct? Will this work in parallel to the "regular" controls that use the > control framework? No, just use the control framework. You need to make a custom control that is specific to your driver So reserve a range for your driver in include/uapi/linux/v4l2-controls.h (search for 'USER-class private control IDs'). Then you can define a control ID. The next step is to configure the control: static const struct v4l2_ctrl_config cal_table_control = { .ops = &cal_ctrl_ops, .id = V4L2_CID_SUR40_CAL_TABLE, .name = "Calibration Table", .type = V4L2_CTRL_TYPE_U16, .max = 0xffff, .step = 1, .def = 0, .dims = { 960, 540 }, }; And register it with a control handler: v4l2_ctrl_new_custom(hdl, &cal_table_control, NULL); See e.g. drivers/media/pci/solo6x10/solo6x10-v4l2-enc.c and the DETECT_MD controls. Regards, Hans
