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

H. Nikolaus Schaller hns at goldelico.com
Tue Aug 9 16:07:09 CEST 2016


> Am 09.08.2016 um 15:13 schrieb Andrey Utkin <andrey_utkin at fastmail.com>:
> On Tue, Aug 09, 2016 at 01:44:10PM +0200, H. Nikolaus Schaller wrote:
>> Hi Andrey,
>>> Am 09.08.2016 um 12:45 schrieb Andrey Utkin <andrey_utkin at fastmail.com>:
>>> On Fri, Jul 29, 2016 at 08:55:53AM +0200, H. Nikolaus Schaller wrote:
>>>> This allows me to continue to work on the camera driver where I wasn't able
>>>> to install the v4l-utils package to control the ISP (Image Signal Processor)
>>>> of the DM3730 SoC.
>>>> Now the tools are sharp again. Let's start looking into the camera driver...
>>> Please keep me posted about any issues you have with it. (Or give links
>>> to existing tickets.)
>> you mean the camera driver?
>> Well, here are all links:
>> http://projects.goldelico.com/p/gta04-kernel/issues/467/
>> http://git.goldelico.com/?p=gta04-kernel.git;a=shortlog;h=refs/heads/work/hns/video/ov9655
>> http://git.goldelico.com/?p=gta04-kernel.git;a=blob;f=Letux/root/camera-demo;h=2858acac4fad5b684a0ec3a899a0c7b706f64292;hb=07d63901af40477eaa958e18ff0ae9da4c8e03fb
>> http://git.goldelico.com/?p=gta04-kernel.git;a=blob;f=Letux/root/capture-demo;h=e6c86844f04ac668fda6ed34006c533fd1050f11;hb=07d63901af40477eaa958e18ff0ae9da4c8e03fb
>> http://git.goldelico.com/?p=gta04-kernel.git;a=blob;f=Letux/root/capture.c;h=c2a3bc9d176a78850be52afb8aca1eacfab76392;hb=07d63901af40477eaa958e18ff0ae9da4c8e03fb
>> http://electricstuff.co.uk/OV9655-datasheet-annotated.pdf
>> The chip is now recognised and probed successfully. This means the DT setup for the I2C command interface is ok.
>> What has to be done:
>> a) check if the data (video stream) interface setup is correct (does DT choose the correct interface and send out the right clock frequency)
>> but it is likely so since the camera chip needs the system clock to respond on I2C. But there could be pinmux issues.
>> b) which registers have to be programmed in which way through the v4l2 ioctls...
>> We have a very old (working) driver and the ov9650 driver to mix&merge ideas.
>> Probably a very basic and static setup could already work and leave gamma correction, pan, crop, auto-gain, resolution switching for further improvements.
>> c) I do not know if the mediactl setup is still matching the kernel driver's expectations
>> But for all this a developer should have a device with built-in camera for being able
>> to make experiments...
> Thanks for sharing.
> The only way I can help now is to mainline your patches to ov9650
> driver. BTW are they complete, i.e. does the driver from
> work/hns/video/ov9655 do all expected things?

No, not at all. It just probes successfully.

> To test robustness of driver, I'd suggest running
> v4l2-compliance -s -d /dev/videoX
> (after all the media-ctl invocations) and sharing the output with me.
> v4l2-compliance is a lot like Letux/root/capture.c only doing much more
> and carrying authoritative opinion of V4L subsystem maintainers.

Ah, good to know!

> I don't possess gta04 and currnetly not going to obtain one, but if
> there's incentive for me to tackle with it, a lot could be done via ssh
> I believe.

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.


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