S3C244X/S3C64XX SoC camera host interface driver questions

From: Andrey Gusakov <dron_gus@mail.ru>

Hi,

On 11/08/2012 07:47 PM, Andrey Gusakov wrote:
>> Ok, thanks. I will add the missing CONFIG_PM_RUNTIME dependency in Kconfig.
>> The driver has to have PM_RUNTIME enabled since on s3c64xx SoCs there are
>> power domains and the camera power domain needs to be enabled for the CAMIF
>> operation. The pm_runtime_* calls in the driver are supposed to ensure that.
>> I wonder why it works for you without PM_RUNTIME, i.e. how comes the power
>> domain is enabled. It is supposed to be off by default.
> DS says that all power domaint are on after reset. My bootloader did
> not switch then off. So when linux start everything is on.
> CONFIG_PM_RUNTIME was disabled, so nothing switch them off in linux
> too.

Yes, indeed. But there was a PM code added that is supposed to disable all
unused power domains on the system boot. I noticed that one needs to call
explicitly s3c64xx_pm_init() function from machine_init() callback within
the board file. So far this function is called only in mach-crag6410.c.
I'm not sure it it won't kill the display if you use it though. Probably
PM domain state should be read from a respective register and this
information passed to pm_genpd_init() function within s3c64_pm_init().

>>>> I hope to eventually prepare the ov9650 sensor driver for mainline. Your
>>>> help in making it ready for VER=0x52 would be very much appreciated. :-)
>>>
>>> I'll try to helpful.
>>>
>>>
>>>>> Next step is to make ov2460 work.
>>>>
>>>> For now I can only recommend you to make the ov2460 driver more similar
>>>> to the ov9650 one.
>>>
>>> Thanks, I'll try.
>>>
>>> P.S. I add support of image effects just for fun. And found in DS that
>>> s3c2450 also support effects. It's FIMC in-between of 2440 and
>>> 6400/6410. Does anyone have s3c2450 hardware to test it?
>
>> Patches adding image effect are welcome. I'm bit to busy to play with these
>> things, other than I don't have hardware to test it.
>> I wasn't really aware of CAMIF in s3c2450. I think a separate variant data
>> structure would need to be defined for s3c2450. If anyone ever needs it
>> it could be added easily. For now I'll pretend this version doesn't exist.
>> :-)
> Attached.
>
> I often get "VIDIOC_QUERYCAP: failed: Inappropriate ioctl for device"

This is an issue in the v4l2-ctl, it is going to be fixed by adding
VIDIOC_SUBDEV_QUERYCAP ioctl for subdevs. It has been just discussed today.
I guess you get it when running v4l2-ctl on /dev/v4l-subdev* ?

> or "system error: Inappropriate ioctl for device"

I think this one is caused by unimplemented VIDIOC_G/S_PARM ioctls
at the s3c-camif driver.

> Is it because of not implemented set/get framerate func? How this

Yes, I think so. ioctls as above.

> should work? I mean framerate heavy depend of sensor's settings. So
> set/get framerate call to fimc should get/set framerate from sensor.
> What is mechanism of such things?

With user space subdev API one should control frame interval directly
on the sensor subdev device node [1]. For Gstreamer to work with
VIDIOC_G/S_PARM ioctls we need a dedicated v4l2 library (possibly with
a plugin for s3c-camif, but that shouldn't be needed since it is very
simple driver) that will translate those video node ioctls into the
subdev node ioctls [2]. Unfortunately such library is still not available.

> And same question about synchronizing format of sensor and FIMC pads.
> I make ov2640 work, but if did not call media-ctl for sensor, format
> of FIMC sink pad and format of sensor source pad different. I think I
> missed something, but reading other sources did not help.

As I explained previously, s3c-fimc is supposed to synchronize format
with the sensor subdev. Have you got pad level get_fmt callback
implemented in the ov2640 driver ?
Could you post your 'media-ctl -p' output, run right after the system boot ?

[1] 
http://linuxtv.org/downloads/v4l-dvb-apis/vidioc-subdev-g-frame-interval.html
[2] http://git.linuxtv.org/v4l-utils.git/tree/
-----------------------------------------------------------------------------

 From 04b88737f65f772f8b375234a92c7cdd481eac1b Mon Sep 17 00:00:00 2001
From: Andrey Gusakov <dron_gus@mail.ru>
Date: Mon, 5 Nov 2012 15:50:23 +0400
Subject: [PATCH] S3C-FIMC: add effect controls

SN:
I prefer using s3c-camif name, FIMC appears only in later version of
the SoCs. Also would be nice to put at least some brief description why
this patch is needed.

Signed-off-by: Andrey Gusakov <dron_gus@mail.ru>
---
  drivers/media/platform/s3c-camif/camif-capture.c |   58 
++++++++++++++++++++--
  drivers/media/platform/s3c-camif/camif-core.h    |    5 ++
  drivers/media/platform/s3c-camif/camif-regs.c    |   38 ++++++++++----
  drivers/media/platform/s3c-camif/camif-regs.h    |    6 ++-
  4 files changed, 89 insertions(+), 18 deletions(-)

  			      int index);
  void camif_hw_dump_regs(struct camif_dev *camif, const char *label);
-- 1.7.0.4

Otherwise looks good.

--
Thanks,
Sylwester
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S3C244X/S3C64XX SoC camera host interface driver questions

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