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

H. Nikolaus Schaller hns at goldelico.com
Thu Sep 8 11:58:48 CEST 2016

Hi Javier,

> Am 08.09.2016 um 00:20 schrieb Javier Martinez Canillas <javier at osg.samsung.com>:
> On 09/07/2016 06:04 PM, Javier Martinez Canillas wrote:
> [snip]
>>>> Does the omap3isp driver
>>>> probes? and does probe the driver for your attached camera sensor?
>>> Yes, both. Here an excerpt of the boot log and lsmod
>> Yes, both are probed but your camera driver (drivers/media/i2c/ov9650.c) is
>> missing a call to v4l2_async_register_subdev() in its probe function to be
>> registered async with the bridge driver (omap3isp). You need something like
>> commit c7d97499cc8a ("[media] tvp5150: add support for asynchronous probing")
> In fact, I went and wrote the patch since is pretty trivial. Could you please
> test it and if that's the fixes your problem then I can post it to the list?

Yes!!! It makes the significant difference (I would have searched some more weeks
for it without your help :):

root at letux:~# ls -l /dev/media*
crw------- 1 root root 245, 0 Jan  1  2000 /dev/media0
root at letux:~# ls -l /dev/video*
crw-rw---- 1 root video 81, 0 Jan  1  2000 /dev/video0
crw-rw---- 1 root video 81, 1 Jan  1  2000 /dev/video1
crw-rw---- 1 root video 81, 2 Jan  1  2000 /dev/video2
crw-rw---- 1 root video 81, 3 Jan  1  2000 /dev/video3
crw-rw---- 1 root video 81, 4 Jan  1  2000 /dev/video4
crw-rw---- 1 root video 81, 5 Jan  1  2000 /dev/video5
crw-rw---- 1 root video 81, 6 Jan  1  2000 /dev/video6
root at letux:~# 

I still get a "green" image in mplayer but that could be bugs or missing pieces
in our camera module setup, which I wasn't able to debug so far.

We use an ov9655 chip and the original platform data based driver is for ov9650
and ov9652 only. And these sensors have a slightly different register set which
we have to account for.

So we currently disable I2C writing to the camera so that the module comes up
in default settings.

Regarding your patch I could also submit it together with the full set of driver
patches (we have added DT support) if you agree. But I don't see any issues if you
submit it separately.

The latest patch set (including it) is here:


This also includes one patch for the isp driver which silences a bad of_node_put() warning.
This could also be submitted separately. Should I?

For the DT style topic we currently have this style to have an endpoint
reference at some separate location in the DT source file.

The reason is that we merge several patch sets into a single one and multiple of
them touch the DTS. This construction reduces the risk of difficult to solve
git merge conflicts and patch set dependencies because changes to &parallel_ep
are not within the code line range of i2c devices. So git merge can more easily
identify hunks with inexact line number references.

So indeed it is more difficult to read, but easier to maintain and debug
(during development). But if it becomes stable I think it can be inlined
as you suggest.

BR and many thanks for the help,

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