Soc-camera and 2.6.33

Soc-camera and 2.6.33

[Robert Jarzmik]

I tried to upgrade from 2.6.30 to 2.6.33 and verify my board (ie. the mt9m111
sensor with pxa_camera host).

I'm a bit surprised it didn't work. I dig just a bit, and found that :
 - in soc_camera_init_i2c(), the following call fails
	subdev = v4l2_i2c_new_subdev_board(&ici->v4l2_dev, adap,
				icl->module_name, icl->board_info, NULL);
   I have subdev = NULL.

 - as a result, I'm getting that kind of log :
     camera 0-0: Probing 0-0
     pxa27x-camera pxa27x-camera.0: Registered platform device at c3010900 data c03f0c24
     pxa27x-camera pxa27x-camera.0: PXA Camera driver attached to camera 0
     RJK: subdev=NULL, module=mt9m111
     pxa27x-camera pxa27x-camera.0: PXA Camera driver detached from camera 0
     camera: probe of 0-0 failed with error -12

 - if I try 2.6.34, I have no error report, and mt9m111 driver is not probed
   either.

Is there an explanation as to why I have this regression ? Is something to be
done with the v4l2 migration ?

Cheers.

--
Robert

Re: Soc-camera and 2.6.33

[Guennadi Liakhovetski]

Hi Robert

On Mon, 31 May 2010, Robert Jarzmik wrote:

> I tried to upgrade from 2.6.30 to 2.6.33 and verify my board (ie. the mt9m111
> sensor with pxa_camera host).
> 
> I'm a bit surprised it didn't work. I dig just a bit, and found that :
>  - in soc_camera_init_i2c(), the following call fails
> 	subdev = v4l2_i2c_new_subdev_board(&ici->v4l2_dev, adap,
> 				icl->module_name, icl->board_info, NULL);
>    I have subdev = NULL.
> 
>  - as a result, I'm getting that kind of log :
>      camera 0-0: Probing 0-0
>      pxa27x-camera pxa27x-camera.0: Registered platform device at c3010900 data c03f0c24
>      pxa27x-camera pxa27x-camera.0: PXA Camera driver attached to camera 0
>      RJK: subdev=NULL, module=mt9m111
>      pxa27x-camera pxa27x-camera.0: PXA Camera driver detached from camera 0
>      camera: probe of 0-0 failed with error -12

a lot of things changed in and around soc-camera between 2.6.30 and 
.33... E.g., previously you could load driver modules in any order, it 
would work in any case. Now if you load your host driver (pxa) and your 
client driver is not there yet, it should be automatically loaded. 
However, if your user-space doesn't support this, it won't work. Can this 
be the reason gor your problem? Otherwise, I'd suspect a problem with your 
platform data (cf. other platforms), or, eventually with mt9m111.

>  - if I try 2.6.34, I have no error report, and mt9m111 driver is not probed
>    either.
> 
> Is there an explanation as to why I have this regression ? Is something to be
> done with the v4l2 migration ?

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/

Re: Soc-camera and 2.6.33

[Robert Jarzmik]

Guennadi Liakhovetski <g.liakhovetski@gmx.de> writes:

> Hi Robert
>
> a lot of things changed in and around soc-camera between 2.6.30 and 
> .33... E.g., previously you could load driver modules in any order, it 
> would work in any case. Now if you load your host driver (pxa) and your 
> client driver is not there yet, it should be automatically loaded. 
> However, if your user-space doesn't support this, it won't work. Can this 
> be the reason gor your problem? Otherwise, I'd suspect a problem with your 
> platform data (cf. other platforms), or, eventually with mt9m111.

I have a very tiny system :
 - udev
 - a shell (/bin/ash)
 - a libc
 - busybox (insmod/modprobe/rmmod/ls)
 - capture_example compiled as my testbed

I do :
 - insmod mt9m111.ko
 - insmod pxa_camera.ko

My userspace hasn't changed since 2.6.30 (constant executables, ARM-EABI). My
platform was converted by you in commit a48c24a696f0d93c49f913b7818e9819612b1f4e
if I remember correctly.

Any hint for me to track down my problem ?

Cheers.


-- 
Robert

Re: Soc-camera and 2.6.33

[Robert Jarzmik]

Guennadi Liakhovetski <g.liakhovetski@gmx.de> writes:

> a lot of things changed in and around soc-camera between 2.6.30 and 
> .33... E.g., previously you could load driver modules in any order, it 
> would work in any case. Now if you load your host driver (pxa) and your 
> client driver is not there yet, it should be automatically loaded. 
> However, if your user-space doesn't support this, it won't work. Can this 
> be the reason gor your problem? Otherwise, I'd suspect a problem with your 
> platform data (cf. other platforms), or, eventually with mt9m111.

I tracked down the beast ... :)

The problem is with the commit a48c24a696f0d93c49f913b7818e9819612b1f4e
"[ARM] pxa/mioa701: convert mioa701 to the new platform-device soc-camera
interface".

This is a tricky one ... :
  - ic_link is declared normally, and references &mioa701_i2c_devices[0]
  - but mioa701_i2c_devices[] is declared as __initdata, and discarded after
  init if I understand correctly.

This implies that the structure ic_link references something not present
anymore, hence my bug. I'm a bit disturbed that the compiler didn't catch that
...

Anyway, now I'll have to send a patch to Eric for that, to remove the
"__initdata" specifier from mioa701_i2c_devices[].

Eric, are you still taking in fix patches for the 2.6.35 kernel ?

Cheers.

--
Robert

PS: I checked for other pxa boards, and they don't suffer from my problem.

Re: Soc-camera and 2.6.33

[Guennadi Liakhovetski]

On Tue, 1 Jun 2010, Robert Jarzmik wrote:

> Guennadi Liakhovetski <g.liakhovetski@gmx.de> writes:
> 
> > a lot of things changed in and around soc-camera between 2.6.30 and 
> > .33... E.g., previously you could load driver modules in any order, it 
> > would work in any case. Now if you load your host driver (pxa) and your 
> > client driver is not there yet, it should be automatically loaded. 
> > However, if your user-space doesn't support this, it won't work. Can this 
> > be the reason gor your problem? Otherwise, I'd suspect a problem with your 
> > platform data (cf. other platforms), or, eventually with mt9m111.
> 
> I tracked down the beast ... :)
> 
> The problem is with the commit a48c24a696f0d93c49f913b7818e9819612b1f4e
> "[ARM] pxa/mioa701: convert mioa701 to the new platform-device soc-camera
> interface".

hm, I would humbly disagree - the "__initdata" was there before that 
commit. With my conversion I just missed it and noone tested it since 
then;)
> 
> This is a tricky one ... :
>   - ic_link is declared normally, and references &mioa701_i2c_devices[0]
>   - but mioa701_i2c_devices[] is declared as __initdata, and discarded after
>   init if I understand correctly.
> 
> This implies that the structure ic_link references something not present
> anymore, hence my bug.

Nice catch!

> I'm a bit disturbed that the compiler didn't catch that
> ...

Interesting...

> Anyway, now I'll have to send a patch to Eric for that, to remove the
> "__initdata" specifier from mioa701_i2c_devices[].
> 
> Eric, are you still taking in fix patches for the 2.6.35 kernel ?

Of course, bugfixes must be taken at any time.

> PS: I checked for other pxa boards, and they don't suffer from my problem.

And not only PXA.

Thanks for debugging!
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/