Soc-camera and 2.6.33

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 ?

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.

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.

Quoted 7 lines · Guennadi Liakhovetski

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 ?

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