[Letux-kernel] [Gta04-owner] On camera driver

H. Nikolaus Schaller hns at goldelico.com
Tue Aug 9 20:02:22 CEST 2016


Hi,

> Am 09.08.2016 um 19:48 schrieb Andrey Utkin <andrey_utkin at fastmail.com>:
> 
> On Tue, Aug 09, 2016 at 07:22:49PM +0200, H. Nikolaus Schaller wrote:
>> Here is what it says w/o running any media-ctl before:
> 
> Maybe running it after media-ctl may give different results...

well, media-ctrl does not run because it does look for but not find this file:

root at letux:~#  media-ctl -V '"ov9655 2-0030":0 [UYVY2X8 1280x1024]'
Failed to enumerate /dev/media0 (-2)
root at letux:~# 

> 
>> Compliance test for device /dev/video0 (not using libv4l2):
> 
> Maybe other /dev/videoX devices should be tested (I've seen mention of
> /dev/video6).

Ok, we have

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:~# 

> 
>> So it is probed successfully on I2C but there is no /dev/media (if that is what should be looked for here)
> 
> Have never heard of /dev/media files, but i haven't worked with
> media-ctl stuff yet.

I think the ISP driver should create them...

> 
>>>> Hm. Running a GTA04 permanently on ssh is a little tricky. As soon
>>>> as you poweroff it does not reboot automatically. And if you damage
>>>> the SD card contents (a kernel panic during boot) it won't boot to USB
>>>> without manually reflashing the SD card. So it needs supervision which
>>>> I can't provide.
>>> 
>>> So "emergency reboot" like this doesn't reboot either?
>>> 
>>> sync
>>> echo s > /proc/sysrq-trigger
>>> sleep 1
>>> echo b > /proc/sysrq-trigger
>> 
>> How should that work if it does not boot up to an USB interface? How can
>> we remotely issue such commands?
> 
> I meant to do this to get a proper reboot when we are fully booted,
> replying to your statement "as you poweroff it does not reboot
> automatically".
> 
>> I mean the case that you did write a new uImage on the /boot partition
>> or kernel module to /lib/modules over your ssh connection and then you do
>> a reboot. But the uImage or some kernel module is broken now.
> 
> Nothing should be broken after "sync" command - it is supposed to flush
> any disk caches.


Ah, I don't mean corruption while not syncing (Debian poweroff/reboot does a
clean sync) before reboot and having just a corrupt SD card. I mean corrupt
source code compiled into a corrupt driver. Something like *((int 0))=0; and
then reboot that one.

Anyways the result is the same.

BR,
Nikolaus



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