I encountered a strange problem regarding mx8_v4l2_cap_drm.c

[783435100]

Dear technical support:
   mx8_v4l2_cap_drm.c,
   I removed part of the DRM code, kept the v4l2 code, compiled my own mx8_v4l2_cap_drm.out with aarch64-linux-gnu-gcc and run it to ioctl(fd_v4l, VIDIOC_S_PARM, &parm). The return value is -1, and the mx8_v4l2_cap_drm.out provided by the system can be normal Run, why? Thank you!

[igorpadykov · Accepted solution]

Hi 783435100

one can try to debug it using Video for Linux API documentation and error codes description :

https://siqueira.tech/doc/drm/userspace-api/media/v4l/vidioc-g-parm.html#c.VIDIOC_S_PARM

https://siqueira.tech/doc/drm/userspace-api/media/gen-errors.html#id1

Best regards
igor