Problem in `VIDIOC_G/TRY/S_FMT` on `allow_scaling=1` and `allow_cropping=1` about vcam HOT 3 CLOSED

Thanks for @WayneLin1992 's reply!

3. I think vivid_try_fmt_vid_cap only fill in negotiate information to user, but didn't actually reset the size setting from the device. vivid_s_fmt_vid_cap is the function which change the device setting. I still think it is better to change the behavior according to the API description.
5. Is it better to bind two update function vcamfb_update and vcam_in_queue_destroy/setup together? Which in former function rebuild vcamfb but only change in_queue attribute, and the latter one only rebuild in_queue without vcamfb.
6. This question extend from question 5: if we want to change the in/out_queue setting, is it necessary to destroy and init a new in/out_queue, or we only need to change the attribute only? And this is the reason why in your vcamfb_update implementation, you only change the attribute on in/out_queue instead of re-init them?

from vcam.

2. you can set

const struct v4l2_frmsize_discrete *sz = v4l2_find_nearest_size(
            vcam_sizes, n_avail, width, height, f->fmt.pix.width,
            f->fmt.pix.height);

, and you would pass the scaling test on v4l2-compliance.
3. TRY_FMT should not change the driver state, but it could reset the size.
reference vivid_try_fmt_vid_cap
The vivid is a Linux kernel test device driver and pass all v4l2-compliance test.
5. fb.c/vcamfb_update can remalloc space for the sizeimage, and set var.xres var.yres actually seen on the window.
The var.xres_virtual and var.yres_virtual are real space size in memory.
reference The Frame Buffer Device
6.control.c/control_iocontrol_modify_input_setting use the old API need to change.

from vcam.

Thanks for @kevinshieh0225
3. Your ideal is correct. TRY_FMT it will fill format negotiated for device, and S_FMT is actually reset the device size from format.
4.
5. Your ideal is correct. vcam_in_queue_destroy/setup is old API for vcamfb, so it need to combine with vcamfb_update.
6. You only need to change the attribute on in_queue.

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