[Letux-kernel] omap3 isp -- media-ctl

H. Nikolaus Schaller hns at goldelico.com
Wed Sep 7 17:29:11 CEST 2016


Hi Javier,
I am trying to upgrade our camera subsystem on a omap3 board
to use the latest DT based kernel but have trouble using the
media-ctl tool as before (we have a working setup on 3.12).

Problem 1: there is no /dev/media*

root at letux:~# media-ctl -v -p
Opening media device /dev/media0
media_device_open: Can't open media device /dev/media0
Failed to enumerate /dev/media0 (-2)
root at letux:~# ls -l /dev/media*
ls: cannot access /dev/media*: No such file or directory
root at letux:~# ls -l /dev/video*
crw-rw---- 1 root video 81, 0 Sep  7 12:17 /dev/video0
crw-rw---- 1 root video 81, 1 Sep  7 12:17 /dev/video1
crw-rw---- 1 root video 81, 2 Sep  7 12:17 /dev/video2
crw-rw---- 1 root video 81, 3 Sep  7 12:17 /dev/video3
crw-rw---- 1 root video 81, 4 Sep  7 12:17 /dev/video4
crw-rw---- 1 root video 81, 5 Sep  7 12:17 /dev/video5
crw-rw---- 1 root video 81, 6 Sep  7 12:17 /dev/video6
root at letux:~#

Problem 2: if I try to use /dev/video*

root at letux:~# media-ctl -v -d /dev/video0 -p
Opening media device /dev/video0
media_device_enumerate: Unable to retrieve media device information for device /dev/video0 (Inappropriate ioctl for device)
Failed to enumerate /dev/video0 (-25)
root at letux:~# 

So do you have some working example how to successfully control
the ISP from user space with latest kernels?

Our setup:
* kernel 4.8-rc5 (with patches for the camera module)
* Debian Jessie
* v4l-utils (Jessie)

I have also tried to build the latest (stable = 1.10.1) media-ctl from
https://git.linuxtv.org/v4l-utils.git
but see no difference.

Our old setup did simply work with media-ctl on /dev/media0 and no
-d option required.

BR and thanks for any hints,
Nikolaus




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